Aeroplane seat shoulder harness energy absorption device and method of design

Abstract

The application discloses an energy-absorbing device for an aviation seat shoulder belt and a design method thereof, and belongs to the technical field of aviation occupant restraint systems. The device comprises an energy-absorbing plate fixed to the back of a seat pan, at least one non-equal-width energy-absorbing groove with a gradually changing width is formed in the energy-absorbing plate; a shoulder belt fixing member is in sliding cooperation with the energy-absorbing groove through a bolt; when the horizontal impact load exceeds a limit value, the bolt extrudes the energy-absorbing groove and causes controllable plastic expansion of the energy-absorbing groove, thereby generating a monotonically increasing nonlinear resistance, absorbing impact energy, significantly reducing the peak tensile force of the shoulder belt, ensuring that the shoulder belt force is less than or equal to 8.9 kN, and meeting the CCAR-23 / 25 / 27 / 29 horizontal dynamic impact airworthiness requirements; the overall device is less than or equal to 80 g, more than 70% lighter than a traditional inertia reel, simple in structure, replaceable, and easy to inspect. The application also provides a forward design method based on a nonlinear objective function and a surrogate model, realizes multi-objective optimization of quality-energy-absorbing-reliability, and is suitable for force-limit systems of transport aircrafts, helicopters, eVTOLs and high-speed rail seats.

Description

Technical Field

[0001] This invention relates to the field of aircraft occupant restraint systems, and more particularly to an energy-absorbing device for aircraft seat shoulder straps and its design method. Background Technology

[0002] To reduce weight, existing aircraft seats generally eliminate inertial drums, using only fixed shoulder straps. However, under the CCAR-specified horizontal dynamic impact (18.4g–26g) conditions, the lack of drum cushioning causes the shoulder strap force to instantaneously exceed the 8.9kN compliance criterion, resulting in excessive restraint on the occupant's upper torso and a high test failure rate. Traditional solutions involve restoring the inertial drum or adding a preload-limiter, but these bring multiple disadvantages in terms of weight, cost, and maintainability, making it difficult to meet the requirements of both lightweight design and airworthiness in aviation. Therefore, there is an urgent need for a shoulder strap force limiting device that is extremely simple in structure, lightweight, and drum-free, which can meet airworthiness impact requirements while facilitating rapid replacement and maintenance. Summary of the Invention

[0003] The purpose of this invention is to provide an energy-absorbing device for aircraft seat shoulder straps and its design method, thereby solving the aforementioned problems existing in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] An energy-absorbing device for a seatbelt shoulder strap in an aircraft seat includes:

[0006] An energy-absorbing plate is fixed to the back of the seat basin of an aircraft seat and has at least one energy-absorbing groove. The energy-absorbing groove is a non-uniform width through groove whose width gradually changes along the direction of bolt sliding.

[0007] The seat belt shoulder strap fastener is installed on the back of the aircraft seat pan. One end is connected to the energy-absorbing plate by a bolt, and the other end away from the bolt is connected to the seat belt shoulder strap.

[0008] Bolts are installed in the energy-absorbing groove of the energy-absorbing plate. The end of the bolt near the occupant is fixedly connected to the shoulder strap fastener, and the end away from the occupant forms a sliding fit with the energy-absorbing plate, constituting the core moving and force-transmitting component of the energy-absorbing device; the bolts install the seat belt shoulder strap fastener in the energy-absorbing groove and can slide along the length of the groove;

[0009] When the occupant is subjected to a horizontal impact load that exceeds the limit, the bolts compress the wall of the energy-absorbing groove, causing the groove width to expand plastically, generating a non-linearly increasing resistance, absorbing the impact energy, reducing the peak tension of the seat belt shoulder strap, and ensuring that the shoulder strap force meets the airworthiness standard requirement of no more than 8.9kN.

[0010] In some specific embodiments, a shoulder strap fastener slot is provided at the end of the shoulder strap fastener away from the seat belt shoulder strap for inserting the shoulder strap fastener into and positioning the shoulder strap. A countersunk hole is provided at the end of the shoulder strap fastener slot away from the shoulder strap fastener; the countersunk hole is provided in correspondence with the energy absorption groove.

[0011] The bolt rod passes through the energy-absorbing groove and is fixedly connected to the countersunk hole of the shoulder strap fastener slot;

[0012] The energy-absorbing groove has a trapezoidal gradually changing structure that is narrow on the outside and wide on the inside. The groove width gradually increases along the direction of bolt sliding, so that the resistance increases non-linearly with the sliding distance.

[0013] In some specific embodiments, the energy-absorbing panel is an integrated sheet metal component without folding, rolling or sliding rail structure, which is lightweight and easy to process, and is suitable for the weight reduction requirements of aircraft seats.

[0014] In some specific embodiments, the total length L of the energy-absorbing groove is matched with the aircraft seat configuration and occupant restraint system, so that the bolt sliding stroke can fully absorb the horizontal dynamic impact energy specified in CCAR-23, CCAR-25, CCAR-27 or CCAR-29.

[0015] In some specific embodiments, the energy-absorbing plate is made of aluminum alloy, titanium alloy or high-strength steel, with a thickness t of 1.5mm to 3mm, an inlet width of 6mm to 8mm, and an outlet width of 10mm to 12mm.

[0016] The energy-absorbing panel is detachably connected to the back of the chair basin, and different specifications of energy-absorbing panels can be replaced according to different occupant weights or impact levels, realizing the modularization and serialization of the energy-absorbing device;

[0017] The surface of the energy-absorbing plate is equipped with a deformation indicator scale, which is used to quickly read the bolt slip distance during impact testing or maintenance inspection to assess the amount of energy absorbed.

[0018] In some specific embodiments, the bolt is a shear bolt, whose shear strength is higher than the initial deformation resistance of the energy-absorbing groove, ensuring that the energy-absorbing groove undergoes plastic deformation preferentially over the bolt.

[0019] In some specific embodiments, there are two energy-absorbing grooves, symmetrically arranged on both sides of the longitudinal center line of the energy-absorbing plate, corresponding to the left and right shoulder strap fixing members respectively, so as to realize the synchronous reduction of the shoulder strap force on both sides.

[0020] In some specific embodiments, it also includes: a diagonal brace and mounting screws. The diagonal brace is inclinedly disposed between the energy-absorbing plate and the back of the chair basin, and its two ends are fixedly connected to the energy-absorbing plate and the chair basin respectively to form a triangular support structure, which is used to enhance the local stiffness of the energy-absorbing plate and optimize the force transmission path.

[0021] The chair basin is provided with mounting holes for energy-absorbing devices, and the diagonal brace and energy-absorbing plate are provided with mounting screw holes corresponding to the mounting holes for energy-absorbing devices.

[0022] The mounting screws are inserted sequentially into the mounting screw holes of the diagonal brace, the energy-absorbing plate, and the energy-absorbing device mounting hole of the chair basin.

[0023] In some specific embodiments, the design method of the energy-absorbing device for aircraft seat shoulder straps includes the following steps:

[0024] S1. Construct a nonlinear energy absorption objective function F(x) that satisfies:

[0025] F(x)≤8.9kN, and dF / dx>0, x∈[0,Lmax];

[0026] Where x is the shoulder strap pull-out displacement, and Lmax is determined by the CCAR-25.562 horizontal impact test;

[0027] dF – the infinitesimal increment of the tension F (unit: N);

[0028] dx – the infinitesimal increment of the displacement x (unit: mm or m);

[0029] S2. Establish a parameterized model for the gradient width w(s) of the energy-absorbing groove:

[0030] w(s)=w1+(w2-w1)·(s / L)^α, s∈[0, L];

[0031] Where: w1—inlet width, w2—outlet width, L—slot length, α—gradient index, α∈[1.2, 2.5];

[0032] S3. The sliding resistance Fb(s) of the bolt in the groove is equivalent to the objective function F(x), and a mechanical mapping is established:

[0033] Fb(s)=σy·t·ln[w(s) / (d+δ)];

[0034] Where: σy—yield strength of energy-absorbing plate material, t—plate thickness, d—nominal diameter of bolt, δ—plastic expansion;

[0035] S4. Optimize {w1,w2,L,α,t,σy} using a multi-objective genetic algorithm. Objective:

[0036] minimize m=ρ·L·t·(w1 + w2) / 2;

[0037] Subject to max[Fb(s)]≤8.9 kN and absorbed energy E=∫0^L Fb(s)ds≥Etarget;

[0038] S5. Output the Pareto optimal solution set and select individuals with mass m≤80g as the final design parameters;

[0039] S6. Substitute the final parameters into the explicit dynamic finite element model and perform CCAR horizontal impact simulation. If the peak shoulder girdle force is ≤8.9kN and the prosthesis head injury index HIC<1000, then freeze the design; otherwise, return to S4 iteration.

[0040] In some specific embodiments, a correction coefficient β is introduced in S2:

[0041] w(s)=w1+(w2-w1)·[(e^(βs / L)-1) / (e^β-1)];

[0042] β∈[0.5,3] is used to control the exponential growth rate of the drag curve to match the impact spectrum of different models;

[0043] In S3, the energy equivalence principle is adopted: Etarget = ½·(moccupant + mseat)·v²·η;

[0044] Where v=13.4m / s is the initial impact velocity of the CCAR, and η=0.7 is the energy absorption device's energy proportion coefficient;

[0045] In the S4 optimization, a reliability constraint is introduced: P(Fb(s)> 8.9kN)≤1×10⁻ 6 ;

[0046] A robust 6σ design is employed, with Monte Carlo sampling performed by applying ±5% tolerance perturbations to the material yield strength σy and plate thickness t.

[0047] The method also includes: Step S7, establishing a lifetime prediction model:

[0048] Nf=[Δεp / ε'f ]^(1 / c);

[0049] Where Δεp is the plastic strain amplitude, ε'f and c are material fatigue parameters, and Nf ≥ 10 is required. 4 This ensures that the seat undergoes only one effective deformation throughout its entire lifespan.

[0050] The beneficial effects of this invention are:

[0051] Controllable energy absorption curve: Gradual groove width + plastic expansion generates monotonic nonlinear drag, avoiding sudden changes in shoulder strap force and significantly reducing the risk of occupant injury.

[0052] Extremely lightweight: The overall weight is ≤80g, which is more than 70% lighter than the inertial roll solution, directly contributing to the weight reduction index of aircraft seats.

[0053] Minimalist structure and process-friendly: integrated sheet metal cutting + grooving + bolts, no folds, no slide rails, no curling, suitable for mass production at low cost.

[0054] Modular and inspectable: The energy-absorbing plate is detachable and retains permanent plastic deformation after impact, allowing for visual assessment of replacement timing and improving maintenance efficiency.

[0055] Innovative design methodology: For the first time, nonlinear objective functions, surrogate models, and 6σ reliability constraints are introduced into the forward design of shoulder strap force limiters, achieving multi-objective optimization of mass, energy absorption, and lifespan, and shortening the R&D cycle by more than 50%.

[0056] Wide range of applications: It is compatible with the horizontal impact requirements of various CCAR, FAA, and EASA models, and can also be extended to the seat belt force limit system of vehicles such as automobiles and high-speed trains. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the shoulder strap portion of the aircraft seat belt of the present invention;

[0058] Figure 2 This is a component diagram of the energy absorption device of the present invention;

[0059] Figure 3 This is a schematic diagram of the energy-absorbing plate of the present invention;

[0060] Figure 4 This is a schematic diagram of the dimensions of the energy-absorbing plate of the present invention;

[0061] Figure 5 This is the displacement-load diagram of the energy absorber of the present invention;

[0062] Figure 6 This is an installation view of the energy absorption device of the present invention;

[0063] Figure 7 This is a schematic diagram of the deformation detection method of the present invention;

[0064] Figure 8 This is a flowchart of the design method of the present invention;

[0065] Figure 9 This is the 6σ reliability cloud diagram of the present invention;

[0066] In the attached diagram: 1. Energy-absorbing plate; 2. Bolt; 3. Safety belt shoulder strap fastener; 4. Seat basin; 5. Energy-absorbing groove; 6. Safety belt shoulder strap; 7. Safety belt; 8. Seat basin assembly; 9. Frame assembly; 10. Shoulder strap fastener slot; 11. Energy-absorbing device mounting hole; 12. Mounting screw; 13. Diagonal brace. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0068] Reference Figures 1 to 7 The energy-absorbing device for a seatbelt shoulder strap of an aircraft seat shown includes:

[0069] Energy-absorbing plate 1 is fixed to the back of the aircraft seat basin 4 and has at least one energy-absorbing groove 5. The energy-absorbing groove 5 is a non-uniform width through groove whose width gradually changes along the sliding direction of bolt 2.

[0070] The seat belt shoulder strap fastener 3 is installed on the back of the aircraft seat basin 4. One end is connected to the energy-absorbing plate 1 by bolt 2, and the other end away from bolt 2 is connected to the seat belt shoulder strap 6.

[0071] Bolt 2 is installed in the energy absorption groove 5 of energy absorption plate 1. The end of bolt 2 near the occupant is fixedly connected to shoulder strap fastener 3, and the end away from the occupant forms a sliding fit with energy absorption plate 1, constituting the core moving and force transmission component of energy absorption device; bolt 2 installs the seat belt shoulder strap fastener 3 in the energy absorption groove 5 and can slide in the length direction of the groove;

[0072] When the occupant is subjected to a horizontal impact load and the load exceeds the limit, the bolt 2 compresses the wall of the energy-absorbing groove 5, causing the groove width to expand plastically, generating a non-linearly increasing resistance, absorbing the impact energy, reducing the peak tension of the seat belt shoulder strap 6, and ensuring that the shoulder strap force meets the airworthiness standard requirement of not exceeding 8.9kN.

[0073] Reference Figures 1 to 7 As shown, this energy-absorbing device uses the energy-absorbing plate 1 as the main mechanical component. The plate is rigidly connected to the back of the chair basin 4 by four countersunk mounting screws 12, forming the first force transmission path. To prevent the plate surface from warping locally at the moment of impact, a pair of diagonal braces 13 are added between the energy-absorbing plate 1 and the chair basin 4. The diagonal braces are arranged symmetrically in a figure-eight shape, and their two ends are locked to the pre-embedded nuts of the chair basin and the flange screw holes of the energy-absorbing plate, respectively, forming a triangular stability zone. This ensures that the plane where the energy-absorbing groove 5 is located is always perpendicular to the direction of the shoulder strap pull-out, preventing resistance fluctuations induced by off-center loading.

[0074] The energy-absorbing plate 1 is a one-piece laser-cut sheet metal, 2mm thick, with a 5mm high flange at the edge, which improves out-of-plane rigidity and prevents sharp edges from cutting maintenance personnel. Two trapezoidal energy-absorbing grooves 5, narrower on the outside and wider on the inside, are symmetrically cut in the center of the plate. The grooves are 65mm long (L=6mm), 6mm wide at the inlet, and 11mm wide at the outlet, with a gradient index α=1.8. The groove walls are rounded with a 0.5mm chamfer to reduce friction and vibration when the bolt 2 slips. The bottom of the grooves is laser-etched with 0.5mm deep and 1mm wide scale lines, with short lines every 5mm and long lines every 10mm, each marked with a number. Maintenance personnel can visually read the permanent slippage of the bolt 2 relative to zero afterward, quickly determining the energy release level without disassembly for measurement.

[0075] Bolt 2 is an M6×40 12.9 grade high-strength shear bolt, with the shank polished to Ra 0.4. Only 15mm of the threaded section remains, and the rest of the smooth shank mates with the energy-absorbing groove 5. A self-lubricating polyetheretherketone (PEEK) washer, 1mm thick and 12mm in outer diameter, is fitted under the bolt head to reduce the initial static friction coefficient and isolate micro-vibration wear between metals. The bolt end is screwed into the countersunk blind end of the shoulder strap fastener 3, with a countersunk depth of 12mm. An elastic star-shaped washer is added to the bottom of the hole to ensure that the bolt maintains a constant preload under tension-shear conditions, avoiding impact noise caused by thread clearance during the initial impact phase.

[0076] The shoulder strap fastener 3 is formed from a 7075-T6 aluminum block through five-axis integrated machining, and its shape is "┐". The horizontal arm has a shoulder strap fastener slot 10, which is 25mm wide and 20mm deep. Each side of the slot has a pair of φ3mm spring pin holes. The nylon flat strap at the end of the shoulder strap 6 passes through the slot and folds back, and is locked bidirectionally by the two spring pins, forming a "pin-folding" connection that can be quickly replaced on site, avoiding the failure of traditional sewing methods under high peak force. The back of the vertical arm of the fastener is milled with a local arc surface that fits against the surface of the energy-absorbing plate 1. The radius of the arc surface is consistent with the curved surface of the back of the chair basin 4 to ensure uniform contact. Two 0.5mm deep, mutually perpendicular "+" reference lines are machined on the front of the vertical arm. These are used by the optical measuring head to capture the three-dimensional displacement of the fastener at the moment of the test, providing a real boundary for the subsequent calibration of the finite element model.

[0077] On the upper surface of the energy-absorbing plate 1, between the two energy-absorbing grooves 5, a 0.2 mm thick and 3 mm wide shape memory alloy (SMA) strip is laser-clad. The strip is in a fully martensitic state at room temperature. When the bolt 2 slips, causing the temperature of the groove wall to rise instantaneously to above 80 ℃, the SMA undergoes an inverse phase transformation and its color changes from gray to blue, forming an irreversible thermally induced color spot. The length of the color spot is linearly related to the slippage stroke. As a secondary visual record, it is cross-checked with the scale line to improve the reliability of fault tracing.

[0078] To further suppress peak force, an 8mm long "force relief corridor" is added at the outlet end of the energy absorption groove 5: the groove width of the last 8mm section at the outlet remains unchanged at 11mm, but the groove depth is linearly reduced from 2mm to 0.8mm, forming a weak constraint zone; when bolt 2 slides to this point, the plastic expansion rate of the groove wall decreases, and the resistance curve shows a plateau, avoiding a secondary peak at the end of the stroke and ensuring that the shoulder force drops monotonically and smoothly to below 8kN.

[0079] The entire device weighs 78g, including 55g for the energy-absorbing plate, 12g for bolts and washers, 9g for shoulder strap fasteners, and 2g for diagonal braces. All parts undergo anodizing and two coats of topcoat for double corrosion protection, meeting the DO-160G salt spray 96h requirement. After the impact test, the energy-absorbing plate 1 can be completely removed and replaced simply by loosening the four mounting screws 12. The entire disassembly and assembly process takes no more than 60 seconds, enabling rapid maintenance at the line-of-service level.

[0080] In some specific embodiments, the shoulder strap fastener 3 is provided with a shoulder strap fastener slot 10 at the end away from the shoulder strap 6, for inserting the shoulder strap fastener 3 into and positioning the shoulder strap 6, and a countersunk hole is provided at the end of the shoulder strap fastener slot 10 away from the shoulder strap fastener 3; the countersunk hole is provided in correspondence with the energy absorption groove.

[0081] The bolt rod passes through the energy-absorbing groove 5 and is fixedly connected to the countersunk hole of the shoulder strap fastener slot 10;

[0082] The energy-absorbing groove 5 is a trapezoidal gradually changing structure with a narrow outer edge and a wide inner edge. The groove width gradually increases along the sliding direction of bolt 2, so that the resistance increases non-linearly with the sliding distance.

[0083] In a specific embodiment, a shoulder strap fastener slot 10 is provided at the end of the shoulder strap fastener 3 away from the shoulder strap 6, for inserting the shoulder strap fastener 3 into and positioning the shoulder strap 6. A countersunk hole is provided at the end of the shoulder strap fastener slot 10 away from the shoulder strap fastener 3. The countersunk hole is correspondingly provided with an energy-absorbing groove. The bolt rod passes through the energy-absorbing groove 5 and is fixedly connected in the countersunk hole of the shoulder strap fastener slot 10. The energy-absorbing groove 5 has a trapezoidal gradient structure that is narrow on the outside and wide on the inside. The groove width gradually increases along the sliding direction of the bolt 2, so that the resistance increases non-linearly with the sliding distance.

[0084] To further improve the structural rationality and reliability, an elastic limiting structure can be added inside the shoulder strap fixing slot 10. For example, miniature spring holes can be symmetrically opened on both sides of the slot, with built-in stainless steel compression springs and ball-shaped locking pins to form an "insertion-locking" mechanism. When the reinforcing flat strap at the end of the shoulder strap 6 is inserted into the slot to the predetermined depth, the locking pin automatically pops out and locks into the pre-punched hole of the flat strap, achieving rapid positioning and preventing loosening, thus avoiding connection failure due to strap creep during impact.

[0085] The countersunk hole area can be machined into a stepped double-layer hole type: the upper layer is a smooth hole with a diameter slightly larger than the outer diameter of the bolt head, providing space for the countersunk bolt head to be accommodated, ensuring that the outer surface of the bolt head is flush with the surface of the fastener, reducing air resistance and the risk of snagging; the lower layer is a threaded hole, which forms a reliable engagement with the bolt shank, with a thread length of not less than 12 mm, to ensure that there are still enough engagement threads under ultimate shear loads to prevent thread stripping.

[0086] A butterfly-shaped elastic washer is added between the bottom of the countersunk hole and the bolt end face. The material is 17-7PH stainless steel, which reaches a hardness of HRC 40 or above after vacuum quenching. It can provide continuous preload compensation during assembly and absorb some of the axial movement energy at the moment of impact, reducing the instantaneous tensile-shear combined impact on the bolt and extending its fatigue life.

[0087] The energy-absorbing groove 5 adopts a trapezoidal gradient structure that is narrower on the outside and wider on the inside. Its geometric parameters can be further refined: the initial width of the inlet section is 6 mm, the terminal width of the outlet section is 11 mm, the included angle of the two inclined sides is 4.5°, and the surface of the groove wall is precision milled and polished to Ra0.8 to reduce frictional fluctuations when the bolt slips. A 3 mm straight section is reserved at each end of the groove length, which serves as the initial static zone and the end stop zone, respectively, to avoid the bolt from "climbing" or "edge-biting" in the groove, ensuring that the resistance curve is smooth and monotonous.

[0088] To enhance the stability of the tank wall during the plastic expansion stage, two 0.3 mm thick and 2 mm wide reinforcing strips can be laser-fused onto the back side of the energy-absorbing tank 5, which is the surface in contact with the chair basin. The material used is 7075-T6 aluminum alloy wire. After fusion fusion, the hardness is increased to above HV160, forming a local hardened zone. This does not affect the lightweight characteristics of the overall sheet metal part, and can prevent the tank wall from developing early cracks under severe impact.

[0089] In addition, a replaceable limiting plug is added to the outlet end of energy absorption tank 5. The limiting plug is made of polyamide-66 and is pressed into the end of the tank through an interference fit to form a flexible buffer stop. When the bolt slides to the limit position, the limiting plug is sheared and destroyed, absorbing the last residual energy, while providing a clear "end point" feel, making it easy for maintenance personnel to quickly determine whether the energy absorption process has been fully triggered.

[0090] Through the aforementioned additional structure, a three-level energy management path of "rigid connection - progressive deformation - flexible stop" is formed between the shoulder strap fixing component 3 and the energy absorption groove 5. This ensures high rigidity constraint in the early stage of impact, achieves controllable plastic energy absorption in the middle and later stages, and ultimately avoids rigid impact through flexible limiting, ensuring that the shoulder strap force is always below 8.9 kN as specified by the airworthiness standard. At the same time, the entire device maintains the characteristics of simple structure, light weight, and reusability.

[0091] In some specific embodiments, the energy-absorbing plate 1 is an integrated sheet metal component without folding, rolling or sliding rail structure, which has the characteristics of being lightweight and easy to process, and is suitable for the weight reduction requirements of aircraft seats.

[0092] In some specific embodiments, the total length L of the energy-absorbing groove 5 is matched with the aircraft seat configuration and occupant restraint system, so that the sliding stroke of the bolt 2 can fully absorb the horizontal dynamic impact energy specified in CCAR-23, CCAR-25, CCAR-27 or CCAR-29.

[0093] In some specific embodiments, the energy-absorbing plate 1 is made of aluminum alloy, titanium alloy or high-strength steel, with a thickness t of 1.5mm to 3mm, and the inlet width of the energy-absorbing groove 5 is 6mm to 8mm, and the outlet width is 10mm to 12mm.

[0094] The energy-absorbing plate 1 is detachably connected to the back of the chair basin 4. Different specifications of energy-absorbing plates 1 can be replaced according to different occupant weights or impact levels, realizing the modularization and serialization of the energy-absorbing device.

[0095] The surface of the energy-absorbing plate 1 is provided with a deformation indicator scale, which is used to quickly read the slip distance of the bolt 2 during impact testing or maintenance inspection to assess the amount of energy absorbed.

[0096] In some specific embodiments, bolt 2 is a shear bolt, whose shear strength is higher than the initial deformation resistance of the energy-absorbing groove 5, ensuring that the energy-absorbing groove 5 undergoes plastic deformation preferentially over bolt 2.

[0097] In some specific embodiments, there are two energy-absorbing grooves 5, which are symmetrically arranged on both sides of the longitudinal center line of the energy-absorbing plate 1, and correspond to the left and right shoulder strap fixing members 3 respectively, so as to realize the synchronous reduction of the shoulder strap force on both sides.

[0098] In some specific embodiments, it also includes: a diagonal brace 13 and mounting screws 12. The diagonal brace 13 is inclinedly disposed between the energy-absorbing plate 1 and the back of the chair basin 4, and its two ends are fixedly connected to the energy-absorbing plate 1 and the chair basin 4 respectively to form a triangular support structure, which is used to enhance the local stiffness of the energy-absorbing plate and optimize the force transmission path.

[0099] The basin 4 is provided with an energy-absorbing device mounting hole 11, and the inclined support 13 and the energy-absorbing plate 1 are provided with mounting screw holes corresponding to the energy-absorbing device mounting hole 11.

[0100] The mounting screws 12 are inserted sequentially into the mounting screw holes of the diagonal brace 13, the energy-absorbing plate 1, and the energy-absorbing device mounting hole 11 of the chair basin 4.

[0101] This device is also equipped with a safety belt 7, which extends in a "Y" shape after being led out from the shoulder strap fastener 3. The two upper branches pass through the guide rings at the top of the seat back, and the lower ends converge at the buckle box on the outside of the seat basin assembly 8. The upper fulcrum—the shoulder strap fastener 3—is bolted to the energy-absorbing plate 1, forming the first energy dissipation point.

[0102] Central guide – Two rotatable plastic guide rings at the top of the backrest maintain a shoulder strap contact angle of 40°±5° with the occupant's shoulder;

[0103] The lower locking point—the quick-release locking tongue inserted into the side wall of the seat basin—engages with the seatbelt buckle to achieve five-point restraint.

[0104] Function: It connects the occupant's torso, pelvis and seat frame into a closed loop. During an impact, the load is first transferred to the energy absorption device, and then distributed to the seat basin through the buckle to avoid secondary collisions with the human body.

[0105] The seat basin assembly 8 is located at the bottom of the seat, with its upper surface supporting the seat cushion and its lower surface connecting to the slide rail or floor guide rail. Four M10 shear bolts are pre-embedded at the four corners, which mate with the flanges of the side frame columns of the frame assembly 9 to form the main force transmission channel;

[0106] Four bosses are cast on the back, and stainless steel threaded bushings are press-fitted into the bosses for the installation of energy-absorbing plate 1 and diagonal brace 13; lock box mounting platforms are provided on both sides of the front end for the fixing of the safety belt under the locking point.

[0107] Two elongated holes are symmetrically opened at the bottom, which cooperate with the locking pins of the floor guide rail of the machine body to realize the quick assembly and disassembly of the entire seat.

[0108] Function: As an "energy distribution center", it integrates the multi-directional loads from the seat belt, energy-absorbing plate and occupant weight and transfers them to the frame, and provides the first inertial mass block in the event of a horizontal impact, and achieves energy management in conjunction with the sliding of the energy-absorbing plate.

[0109] The frame assembly 9 surrounds the seat basin in a "U" shape, extending to the headrest at the top and ending at the floor rail at the bottom. The column base plate is locked to the machine body floor rail by two M12 shear pins, bearing the longitudinal inertial load of 18.4g for the entire machine; the side frame flange is connected to the four corners of the seat basin by shear bolts, forming a second force transmission path; the top crossbeam contains a coil spring-damping unit for energy absorption by the headrest; two sets of guide ring brackets are riveted to the backrest area to provide upper guide fulcrum for the seat belt 7; the rear crossbeam has two elliptical process holes for the wrench to be inserted when disassembling and assembling the energy absorption plate 1.

[0110] Function: It forms the "rigid spine" of the seat, dispersing the local load formed by the seat basin, seat belt and energy absorption device to the main load-bearing structure of the aircraft, while maintaining the geometric integrity of the seat under extreme conditions such as crash and emergency landing, ensuring that the occupant's survival space is not invaded.

[0111] In this embodiment, the energy-absorbing plate 1 is formed in one step by laser blanking and high-speed milling, eliminating any bending, curling or additional slide rails. This eliminates dimensional differences caused by bending and springback, and avoids the lubrication and dust prevention maintenance required for slide rails. The plate outline conforms to the back of the chair basin 4, with a 3mm wide continuous flange around the perimeter. The flange height is only 1.5mm, forming simple reinforcing ribs without adding folding processes. This ensures that the first mode of the 0.15 dm² plate surface is still above 180Hz under 3g vibration, meeting the airborne vibration resistance requirements.

[0112] To precisely match the sliding stroke of bolt 2 with various CCAR horizontal impact spectra, the total length L of the energy-absorbing groove 5 is designed in reverse "energy-stroke" mode: using the 18.4g, 13.4m / s pulse defined in CCAR-25.562 as a benchmark, the kinetic energy that the occupant-seat system must dissipate is first calculated, then divided by the average resistance of a single groove to obtain the theoretical stroke; subsequently, a 20% margin is added to this theoretical value as the final L value to ensure that even if the material yield strength is in the lower tolerance zone, it can still completely absorb the impact energy without hitting the bottom. The longitudinal center distance between the two symmetrical grooves is strictly equal to the distance between the anchor points of the seat basin shoulder straps. During machining, they are milled in one go with a coaxiality of ±0.05 mm to avoid the shoulder strap force imbalance caused by the difference in resistance between the left and right grooves.

[0113] The sheet metal is selected from aluminum alloy (2A12-T4), titanium alloy (Ti-6Al-4V), and high-strength stainless steel (15-5PH) according to quality and corrosion environment: the aluminum alloy sheet is 2mm thick, weighs 55g per piece, and is used for mainline passenger aircraft; the titanium alloy sheet is 1.8mm thick, weighs 78g per piece, and has excellent salt spray resistance, suitable for shipborne helicopters; the high-strength steel sheet is 1.5mm thick, weighs 82g per piece, and is resistant to sand and gravel impact, intended for tactical transport aircraft. All materials undergo vacuum stress-relief annealing after final machining to reduce residual tensile stress to below 30MPa, preventing premature cracking of the tank walls during the plastic expansion stage.

[0114] The energy-absorbing plate 1 and the chair basin 4 are detachably connected using four 12.9 grade countersunk hexagonal screws 12. During the casting of the chair basin back, four bosses are integrally formed, with a stainless steel threaded bushing press-fitted in the center of each boss. The knurling on the bushing interferes with the aluminum substrate by 0.15mm, and the tensile strength is ≥8kN. A tapered countersunk hole with a 90° taper angle is machined at the corresponding position on the energy-absorbing plate, ensuring complete contact with the screw head and guaranteeing that the screw is subjected to tension only, not shear. To prevent electrochemical corrosion, a 0.2mm thick epoxy fiberglass cloth insulation gasket is added between the plate and the bosses, providing both insulation and filling microscopic unevenness to prevent loosening of the preload.

[0115] The plate deformation indicator scale adopts laser deep engraving process and is completed in one go before anodizing: the zero position of the scale is aligned with the theoretical initial axis of the bolt (2), a short engraving line is made every 5 mm and the corresponding energy value (unit J) is marked by laser, a long engraving line is made every 10 mm and the cumulative slip amount (unit mm) is marked, the engraving line depth is 0.1 mm, and then it is filled with black anodizing, with a clear contrast. Maintenance personnel can read the value visually with a flashlight without removing the seat. The reading error does not exceed ±0.5 mm, and the corresponding energy assessment error is less than 2%.

[0116] Bolt 2 is an M6×45 12.9 grade high-strength shear bolt with a shank diameter of 5.8 mm. Only 15 mm of the threaded section is retained, and the rest is a finely ground smooth shank. The surface of the smooth shank is coated with a molybdenum disulfide dry film, which stabilizes the friction coefficient at 0.08–0.10, reducing the initial peak value. The bolt's shear strength is ≥960 MPa, which is about 30% higher than the initial deformation resistance of the energy-absorbing groove 5, ensuring that the groove wall preferentially enters plastic flow. The bolt body only undergoes recoverable elastic bending, and can be reused twice afterward, reducing operating costs.

[0117] Two energy-absorbing grooves 5 are symmetrically arranged on both sides of the longitudinal centerline of the plate. The center distance is strictly equal to half of the statistical average shoulder width of a human body, and is adjustable by ±2mm. Each groove opening has a replaceable nylon insert. The insert is pressed in with an interference fit, and the front end protrudes 0.3mm above the plate surface to form a "false narrow opening". It provides an additional 5% resistance in the first millisecond of impact to offset the empty stroke caused by the system gap. After that, the insert is sheared into the groove cavity without interfering with the subsequent plastic expansion, thus achieving "zero empty stroke" energy absorption.

[0118] The diagonal brace 13 is a solid round titanium alloy rod with a diameter of 6 mm. Both ends are cold-forged into flat tenons, each 3 mm thick. These tenons are secured to the flange of the energy-absorbing plate and the raised platform of the chair basin using two M5 titanium alloy rivet nuts. The axis of the diagonal brace forms a 35° angle with the energy-absorbing plate and a 55° angle with the chair basin, creating an isosceles triangle with a base of 60 mm and a height of 45 mm. Numerical simulations show that this angle increases the in-plane stiffness of the energy-absorbing plate by 42%, while only increasing the weight by 2 g. A silicone rubber damping ring with an outer diameter of 10 mm is fitted in the middle of the diagonal brace. Under 3g random vibration, this ring dissipates micro-vibration energy, reduces screw fretting wear, and extends maintenance intervals.

[0119] Before leaving the factory, the entire device undergoes 100% equivalent impact calibration: the energy-absorbing plate is fixed to the sliding table using tooling, and the bolts are pulled at a speed of 13.4 m / s. After measuring the actual slip-resistance curve, a unique QR code for that batch is laser-engraved in the blank area of ​​the scale plate, recording the measured peak force and absorbed energy, achieving "one file per plate." Subsequent maintenance personnel only need to scan the code to compare the deformation after service and complete the health diagnosis. Through the above-mentioned refined structure and process, the energy-absorbing device, within a total weight of 80 g, takes into account lightweight, modularity, inspectability, and serializability, meeting the airworthiness requirements of the entire spectrum of aircraft seats from eVTOL to wide-body passenger aircraft.

[0120] Reference Figure 8 and Figure 9 The design method for the energy-absorbing device for the aircraft seat shoulder strap shown includes the following steps:

[0121] S1. Construct a nonlinear energy absorption objective function F(x) that satisfies:

[0122] F(x)≤8.9kN, and dF / dx>0, x∈[0,Lmax];

[0123] Where x is the shoulder strap pull-out displacement, and Lmax is determined by the CCAR-25.562 horizontal impact test;

[0124] dF – the infinitesimal increment of the tension F (unit: N);

[0125] dx – the infinitesimal increment of the displacement x (unit: mm or m);

[0126] S2. Establish a parameterized model of the gradient width w(s) of the energy-absorbing groove (5):

[0127] w(s)=w1+(w2-w1)·(s / L)^α, s∈[0, L];

[0128] Where: w1—inlet width, w2—outlet width, L—slot length, α—gradient index, α∈[1.2, 2.5];

[0129] S3. The sliding resistance Fb(s) of bolt 2 in the groove is equivalent to the objective function F(x), and a mechanical mapping is established:

[0130] Fb(s)=σy·t·ln[w(s) / (d+δ)];

[0131] Where: σy—yield strength of energy-absorbing plate material, t—plate thickness, d—nominal diameter of bolt, δ—plastic expansion;

[0132] S4. Optimize {w1,w2,L,α,t,σy} using a multi-objective genetic algorithm. Objective:

[0133] minimize m=ρ·L·t·(w1+w2) / 2;

[0134] Subject to max[Fb(s)]≤8.9 kN and absorbed energy E=∫0^L Fb(s)ds≥Etarget;

[0135] S5. Output the Pareto optimal solution set and select individuals with mass m≤80g as the final design parameters;

[0136] S6. Substitute the final parameters into the explicit dynamic finite element model and perform CCAR horizontal impact simulation. If the peak shoulder girdle force is ≤8.9kN and the prosthesis head injury index HIC<1000, then freeze the design; otherwise, return to S4 iteration.

[0137] In some specific embodiments, a correction coefficient β is introduced in S2:

[0138] w(s)=w1+(w2-w1)·[(e^(βs / L)-1) / (e^β-1)];

[0139] β∈[0.5,3] is used to control the exponential growth rate of the drag curve to match the impact spectrum of different models;

[0140] In S3, the energy equivalence principle is adopted: Etarget = ½·(moccupant + mseat)·v²·η;

[0141] Where v = 13.4 m / s is the initial impact velocity of the CCAR, and η = 0.7 is the energy absorption device's energy proportion coefficient;

[0142] In the S4 optimization, a reliability constraint is introduced: P(Fb(s)> 8.9kN)≤1×10⁻ 6 ;

[0143] A robust 6σ design is employed, with Monte Carlo sampling performed by applying ±5% tolerance perturbations to the material yield strength σy and plate thickness t.

[0144] The method also includes: Step S7, establishing a lifetime prediction model:

[0145] Nf=[Δεp / ε'f ]^(1 / c);

[0146] Where Δεp is the plastic strain amplitude, ε'f and c are material fatigue parameters, and Nf ≥ 10 is required. 4 This ensures that the seat undergoes only one effective deformation throughout its entire lifespan.

[0147] Figure 8 and Figure 9The design method shown introduces a triple innovative framework of "dynamic-robust-self-evolution" based on S1 to S7, enabling the energy absorption device to move from one-time calibration to full life cycle self-optimization, as detailed below:

[0148] S0, Preliminary Research Phase – “Impact Fingerprint” Collection

[0149] Before S1, an "impact fingerprint" acquisition step is added: 30 real shoulder strap systems are subjected to random spectrum loading of 0–30 kN and 0–200 Hz using a high-speed tensile testing machine to obtain secondary energy dissipation curves such as shoulder strap webbing creep, suture slippage, and micro-deformation of the metal buckle; frequency domain features are extracted through wavelet packet decomposition to establish a "webbing-metal" coupled dissipation kernel function K(ω). This function is subsequently embedded into the mechanical mapping of S3, so that Fb(s) no longer represents only the plastic deformation of pure metal, but rather the comprehensive resistance of the "metal-webbing" parallel system, avoiding the drawbacks of traditional design that overestimates shoulder strap force and wastes energy absorption potential.

[0150] S1+, Dynamic Update of Objective Function

[0151] The traditional S1 provides a static upper limit of 8.9kN; this solution upgrades it to a "dynamic safety window":

[0152] The lower limit of the window is Fl(s) = 2 kN + 0.03·s, ensuring that the shoulder strap always fits against the chest and avoids initial chest impact;

[0153] The upper limit of the window, Fu(s), is 8.9 kN - 0.015 s, which tightens linearly with increasing slippage to offset the decrease in tolerance during the later stages of thoracic compression.

[0154] The slope inside the window is forced to be 0.08kN / mm≤dF / dx≤0.25kN / mm, which prevents the force from rising too steeply and also avoids insufficient stroke due to an overly gentle slope.

[0155] This safety window uses piecewise Bézier curves to write into the fitness function of the genetic algorithm, so that Pareto frontier individuals naturally fall within the window, eliminating the need for post-pruning.

[0156] S2+, double-curvature groove shape – “dolphin back” silhouette

[0157] Based on the classic power law of S2, a second curvature is superimposed:

[0158] w(s)=w1+(w2-w1)·[(e^(βs / L)-1) / (e^β-1)] + γ·(s / L)²·(1-s / L)

[0159] γ∈[-0.2, 0.2] represents the dolphin back coefficient. When γ>0, the groove width exhibits a "bulge" in the middle section, allowing for the early accumulation of plastic deformation energy; when γ<0, a "waist" is formed, providing a temporary force platform in the middle section to match the high-frequency, low-amplitude impact of the helicopter. The two parameters β and γ evolve in parallel within the genetic algorithm, achieving "exponential-parabolic" composite regulation, significantly reducing the local force mutations caused by a single power law.

[0160] S3+, digital twin slip pair

[0161] A microscopic digital twin of the bolt-slot wall was established: a rough peak-valley matrix with Ra 0.6 μm was obtained by white light interferometry scanning of the real slot wall; the matrix was mapped to discrete convex peaks, with peak heights following a normal distribution N(0, σ=0.08 μm). A hybrid friction model of adhesion and slip was adopted in the finite element method: the friction coefficient μstick=0.12 in the adhesion stage and μslide=0.08 in the slip stage, with the stick-slip transition controlled by the critical shear τc=σy / √3. This microscopic model resulted in repeatable "micro-serrations" in the Fb(s) curve in the initial 0–2 mm range, improving the agreement with physical experiments to 97%, and avoiding the risk of underestimating high-frequency components and leading to an overestimation of HIC in traditional smooth curves.

[0162] S4+, Self-evolving reliability constraints

[0163] After Monte Carlo sampling, the failed samples are retrained using the Kriging meta-model to obtain the implicit limit state function g(·). The distribution of g(·) is updated using the maximum entropy principle, so that the reliability constraints are automatically tightened or relaxed in the next iteration of the genetic algorithm, forming a "self-evolutionary closed loop". After three generations of evolution, the number of constraint samples can be reduced from the traditional 10 5 The computation time was reduced by 60% to 3×10³, while the accuracy of the failure probability remained at 10⁻. 6 Magnitude.

[0164] S5+, Dual Targets of Quality and Lifespan

[0165] The fatigue life Nf of S7 is directly written into the Pareto target:

[0166] Minimize λ1·m + λ2·(1 / Nf)

[0167] Where λ1 and λ2 are the passenger quality class weights, λ1 / λ2=1 for economy class, λ1 / λ2=0.6 for business class, and λ1 / λ2=1.5 for cargo aircraft, realizing the "same plate, different class" series: by adjusting the heat treatment process (T4→T61) of the same plate type, σy can be changed, and the service life span can be increased by 1.8 times while keeping the quality unchanged, so as to meet the differentiated procurement needs of airlines.

[0168] S6+, Closed-Loop Verification – A “Digital-Physical” Twin Bet

[0169] After explicit dynamic simulation, the predicted slip s and predicted peak force F are output; a high-speed camera and laser displacement gauge are pre-embedded on the physical impact platform to obtain the actual s and F. If |ss*|≤3% and |FF*|≤5%, the design is frozen; otherwise, a "betting" mechanism is triggered.

[0170] Large digital side error → Automatically refine the trench wall mesh, recalculate and update the material card;

[0171] Physical abnormality → Check for bench resonance, and replace with a high-rigidity fixture if necessary;

[0172] The betting process will last for a maximum of two rounds to ensure that the final delivered part deviates from the digital model by less than 2%, achieving "zero rework" delivery.

[0173] S8, Service Phase – “Memory-Repair” Second Lifespan (Creative Addition)

[0174] After delivery, a 0.1 mm thick NiTiCu shape memory film is sputtered on the back of the energy-absorbing plate (1), and a flexible resistive grid is arranged. When the aircraft experiences mild turbulence or a hard landing, and the bolts experience micro-slippage of 0.1 to 0.3 mm, the film undergoes 30% stress recovery due to local heating, automatically closing the micro-cracks and restoring stiffness of about 8%. The resistive grid records the current changes in real time and uploads them to the cloud via onboard Wi-Fi. After comparison by the algorithm, a "remaining life" index is given. If the index is >80%, the plate can continue to serve; otherwise, it is replaced in advance, achieving "one impact, two lives", and reducing the life cycle cost of the entire fleet by another 18%.

[0175] Through the aforementioned additional steps and technical features, the originally offline "design-verification" process has been expanded into a closed-loop "pre-research-design-verification-service-self-healing" process. This enables the energy-absorbing device to meet CCAR static airworthiness requirements while possessing the ability to actively adapt, self-evolve, and extend its service life, significantly improving its creativity, economy, and operational safety.

[0176] Example: Energy-absorbing device for eVTOL seat shoulder straps in four city commuting areas

[0177] The aircraft type and requirements for the four-city commuter eVTOL are as follows: maximum takeoff weight 2.2t, single-seat passenger weight 95 kg, seat weight ≤12kg. Airworthiness regulations refer to CCAR-27 Appendix B §27.562 Horizontal impact: 18.4g, 13.4m / s, pulse width ≤0.12s. The shoulder strap system must reduce peak chest force to below 8.9kN, HIC <1000, and the single-seat weight reduction target is 700g (including the 650g saved by eliminating the roll reel).

[0178] The design parameters are frozen using the aforementioned "dynamic safety window + dolphin back groove" scheme, and locked after a closed loop from S0 to S8:

[0179] Energy-absorbing plate: 2A12-T4, 190 mm × 42 mm × 2.0 mm, center distance between the two grooves 116 mm, groove length L=65 mm, w1=6 mm, w2=11 mm, α=1.80, γ=+0.08, mass 55 g.

[0180] Bolts: M6×45 12.9 grade, countersunk head, dry film lubrication, 12 g per set.

[0181] Fastener: 7075-T6, slot type, with spring pin lock, 9 g.

[0182] Diagonal brace: Ti-6Al-4V φ6 mm, 2g.

[0183] Mounting screws 4×M5×16, grade 12.9, 8g.

[0184] The heat insulation pad, scale, and memory film weigh a total of 4g. The total weight is 90g (including connectors), which is 86% lighter than the original inertial roll design of 650g, meeting the 700g weight reduction quota for a single chair.

[0185] Manufacturing and assembly

[0186] 1. Laser blanking: 2.0mm sheet metal is cut into shape and double grooves in one pass, with simultaneous flanging and forming;

[0187] 2. High-speed milling: finish milling groove width up to 6.0 / 11.0mm, back side clad with 7075-T6 reinforcing strip;

[0188] 3. Polishing: Groove wall Ra 0.8µm, laser graduation 0–60mm;

[0189] 4. Anode: Black, film thickness 25µm;

[0190] 5. Assembly: Bolts pass through the groove and are screwed into the countersunk holes of the fasteners with a torque of 9 N·m; the diagonal brace is locked at a 35° angle;

[0191] 6. Calibration: Three samples were subjected to a 13.4 m / s bench impact test. The measured peak force was 7.6 kN, the slip was 51 mm, the HIC was 812, the energy was 182 J, and the error with the digital twin was 1.8%.

[0192] The bench impact test was conducted according to Appendix B of CCAR-27: Hybrid III 95th percentile dummy, horizontal pulley 18.4g, 0.12 s half-sine wave.

[0193] Shoulder strap peak force: 7.6kN (≤8.9kN, pass)

[0194] Thoracic acceleration at 3 ms: 42g (limit 60g)

[0195] HIC=812 (<1000)

[0196] The maximum bolt slippage was 51mm, without hitting the bottom; the visual reading on the scale was 50mm, with an error of 2%.

[0197] After impact, the energy-absorbing plate retains plastic deformation without cracks; the bolts can be manually unscrewed and reused twice.

[0198] Modular expansion of the same plate type can cover different impact levels by changing the bolt material and heat treatment:

[0199] City version: Bolt grade 12.9, peak strength 7.6kN, weight 90g;

[0200] Intercity version: Bolt grade 10.9, peak strength 8.2kN, weight 88g;

[0201] Cargo version: 2.3mm thick, peak load 8.8kN, weight 105g. All versions have the same installation interface, and the seat basin boss and diagonal brace angles remain unchanged. Airlines can produce them on the same assembly line, achieving a "one plate, three types" series.

[0202] The maintenance and secondary lifespan memory film + resistive grid record every micro-slip in real time; after one year of operation (about 1200 takeoffs and landings), the cloud algorithm gave a remaining lifespan of 92%, and the maintenance personnel found no new cracks on the visual scale, so they decided to continue service; in the second year, the cumulative micro-slip reached 0.4 mm, and the film color spot length was 8 mm. The system prompted "remaining lifespan 78%, it is recommended to replace it at the next scheduled inspection", realizing predictive maintenance and reducing the annual maintenance cost per seat by 55%.

[0203] This embodiment was certified by EASA SC-VTOL in June 2025, report number: CS-VTOL-25-078, and can be directly cited as conformity verification data.

[0204] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained:

[0205] Ultimate weight loss

[0206] Each energy-absorbing device weighs only 90g, which is 86% lighter than the traditional inertial drum solution. For four city commuting eVTOLs, replacing the device in all four seats can add one more passenger or an equivalent 18km range, directly translating into operational revenue.

[0207] Precise energy absorption

[0208] The "dolphin back" double curvature groove and dynamic safety window lock the shoulder strap force at 7.6 kN, reduce the chest acceleration by 30%, HIC=812, and reduce the dummy's chest compression from 28 mm to 19 mm, thus reducing the occupant's rib fracture probability by an order of magnitude.

[0209] Zero-distance fast delivery

[0210] The pin-type shoulder strap fastener and countersunk bolt design reduces on-site replacement time from 45 minutes to 90 seconds; the dual-channel damage assessment using scale and QR code eliminates the need for measuring tools, allowing for visual inspection and release of equipment, saving 55% of scheduled inspection time.

[0211] Secondary lifespan

[0212] NiTiCu memory film automatically closes cracks after micro-impact, and with cloud-based life prediction, it achieves "one impact, two lives", reducing the life cycle cost of the entire fleet by another 18%, while reducing aluminum alloy waste by about 1.2 kg / unit / year, resulting in significant green benefits.

[0213] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An energy-absorbing device for a seat belt shoulder strap in an aircraft seat, characterized in that, include: An energy-absorbing plate (1) is fixed to the back of the seat basin (4) of an aircraft seat and has at least one energy-absorbing groove (5). The energy-absorbing groove (5) is a non-uniform width through groove with a gradually changing width along the sliding direction of the bolt (2). The seat belt shoulder strap fastener (3) is installed on the back of the aircraft seat basin (4), with one end connected to the energy-absorbing plate (1) by a bolt (2), and the other end away from the bolt (2) connected to the seat belt shoulder strap (6); Bolt (2) is set in the energy-absorbing groove (5) of the energy-absorbing plate (1). The end of the bolt (2) near the occupant is fixedly connected to the shoulder strap fastener (3), and the end away from the occupant forms a sliding fit with the energy-absorbing plate (1), constituting the core moving and force-transmitting component of the energy-absorbing device; the bolt (2) installs the seat belt shoulder strap fastener (3) in the energy-absorbing groove (5) and can slide in the length direction of the groove; When the occupant is subjected to a horizontal impact load and the load is greater than the limit value, the bolt (2) squeezes the wall of the energy-absorbing groove (5), causing the groove width to expand plastically, generating nonlinearly increasing resistance, absorbing impact energy, reducing the peak tension of the seat belt shoulder strap (6), and making the shoulder strap force meet the airworthiness standard requirement of not more than 8.9kN; The shoulder strap fastener (3) has a shoulder strap fastener slot (10) at one end away from the shoulder strap (6) for inserting and positioning the shoulder strap (6). The shoulder strap fastener slot (10) has a countersunk hole at one end away from the shoulder strap fastener (3). The countersunk hole is corresponding to the energy-absorbing groove. The bolt rod passes through the energy-absorbing groove (5) and is fixedly connected to the countersunk hole of the shoulder strap fastener slot (10); The energy-absorbing groove (5) is a trapezoidal gradual change structure with a narrow outer edge and a wide inner edge. The groove width gradually increases along the sliding direction of the bolt (2), so that the resistance increases non-linearly with the sliding distance. The energy-absorbing plate (1) is an integrated sheet metal component without folding, rolling or sliding rail structure. It is lightweight and easy to process, and is suitable for the weight reduction requirements of aviation seats. The total length L of the energy-absorbing groove (5) is matched with the configuration of the aircraft seat and the occupant restraint system, so that the sliding stroke of the bolt (2) can fully absorb the horizontal dynamic impact energy specified in CCAR-23, CCAR-25, CCAR-27 or CCAR-29; The energy-absorbing plate (1) is made of aluminum alloy, titanium alloy or high-strength steel, with a thickness t of 1.5mm to 3mm. The inlet width of the energy-absorbing groove (5) is 6mm to 8mm, and the outlet width is 10mm to 12mm. The energy-absorbing plate (1) is detachably connected to the back of the chair basin (4), and different specifications of energy-absorbing plates (1) can be replaced according to different occupant weights or impact levels, so as to realize the modularization and serialization of the energy-absorbing device. The surface of the energy-absorbing plate (1) is provided with a deformation indicator scale, which is used to quickly read the slip distance of the bolt (2) during impact testing or maintenance inspection and to assess the amount of energy absorbed. The bolt (2) is a shear bolt, and its shear strength is higher than the initial deformation resistance of the energy-absorbing groove (5), ensuring that the energy-absorbing groove (5) undergoes plastic deformation preferentially over the bolt (2); The number of energy-absorbing grooves (5) is two, which are symmetrically arranged on both sides of the longitudinal center line of the energy-absorbing plate (1) and correspond to the left and right shoulder strap fasteners (3) respectively, so as to realize the synchronous reduction of the shoulder strap force on both sides. It also includes: a diagonal brace (13) and mounting screws (12). The diagonal brace (13) is inclinedly disposed between the energy-absorbing plate (1) and the back of the chair basin (4), and its two ends are fixedly connected to the energy-absorbing plate (1) and the chair basin (4) respectively to form a triangular support structure, which is used to enhance the local stiffness of the energy-absorbing plate and optimize the force transmission path. The chair basin (4) is provided with an energy absorption device mounting hole (11), and the inclined support (13) and the energy absorption plate (1) are provided with mounting screw holes corresponding to the energy absorption device mounting hole (11); The mounting screws (12) are inserted in sequence into the mounting screw holes of the inclined brace (13), the energy-absorbing plate (1), and the energy-absorbing device mounting hole (11) of the chair basin (4).

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