Automotive crash dummy mechanical muscle device

Abstract

The application discloses a mechanical muscle device of a car crash dummy, and relates to the technical field of car safety testing, comprising an end cover, a positive and negative toothed ball screw, a screw nut, a shell petal, a driving link, a pin shaft and a buffer structure unit, the shell petal is provided with the buffer structure unit, and the dot matrix energy absorption core layer of the buffer structure unit adopts one of an imitation beetle curved rib dot matrix structure, a chiral nested hexagonal structure and a hexagonal FBCC structure. Through mechanical coordination driving of the positive and negative toothed ball screw and the X-shaped scissor unit, the rotational movement of the servo motor is accurately converted into radial expansion and axial contraction of the shell petal, and active tension and passive stretching of the muscle in the collision are accurately simulated. Compared with a pneumatic or hydraulic scheme, the all-mechanical structure has the advantages of rapid response, high control precision and no leakage risk, avoids instability of fluid elements under high-speed impact, and greatly improves the biological simulation degree of the dummy and the reliability of test data.

Description

Technical Field

[0001] This invention relates to the field of automotive safety testing technology, specifically to a mechanical muscle device for an automotive crash test dummy. Background Technology

[0002] With the continuous improvement of automotive safety standards, vehicle crash testing has become a core means of evaluating vehicle safety performance and reducing the risk of occupant injury. As a core tool in testing that replaces the human body, the biosimulation degree of crash test dummies directly determines the validity and reliability of test data. In real traffic accidents, human muscle tissue undergoes complex active tension and passive stretching responses at the moment of impact. This mechanical behavior of muscles directly affects the occupant's posture and its interaction with restraint systems such as seats, seat belts, and airbags.

[0003] However, traditional crash dummy designs primarily focus on simulating the skeletal structure, mass distribution, and joint kinematics of the human body. Their limbs are mostly composed of rigid frames, metal joints, and simple damping elements. While these structures can simulate basic limb movement trajectories, they cannot realistically reproduce the active contraction forces and passive impedance characteristics of muscles during a collision. Especially in tests simulating active pretensioning seatbelts, low-seating occupants, or unconventional seating postures in future autonomous driving scenarios, the lack of muscle simulation in dummies leads to significant differences in dynamic response compared to real humans, thus affecting the accuracy of assessments of key indicators such as whiplash injury, chest compression, and lower limb injuries.

[0004] To address this issue, existing technologies have attempted to introduce muscle simulation components into dummy bodies, but most employ pneumatic or hydraulic drive systems. While these systems can generate some driving force, they generally suffer from complex structures, large size, low control precision, and slow response times. Pneumatic systems are hampered by the compressibility of gases, making precise position control difficult, while hydraulic systems present leakage risks and challenges in piping layout. More importantly, pneumatic and hydraulic components struggle to provide stable and repeatable mechanical performance under the instantaneous impact of high-speed collisions, and the introduction of high-pressure components increases the manufacturing cost and maintenance difficulty of the dummy, limiting its widespread application in actual crash tests. Furthermore, traditional solutions largely lack the ability to simulate the active contraction characteristics of muscles, failing to dynamically adjust muscle tension according to collision conditions, resulting in limited simulation accuracy in complex collision scenarios.

[0005] Therefore, a mechanical muscle device for a car crash test dummy was proposed to solve the above problems. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides the following technical solution: a mechanical muscle device for a car crash dummy, comprising end caps, a ball screw with positive and negative threads, a screw nut, outer shell flaps, an active connecting rod, a pin, and a buffer structure unit. Each end of the ball screw with positive and negative threads is rotatably equipped with an end cap. Four symmetrical outer shell flaps are rotatably mounted on the end caps via pins. An active connecting rod is hinged to the inner side of each outer shell flap. A screw nut is connected to all four active connecting rods. The active connecting rods are hinged to the screw nut. The ball screw with positive threads and a negative threads are provided. Two screw nuts are threadedly engaged with the positive and negative threads respectively. The ball screw with positive and negative threads is connected to an external drive motor via a coupling. The buffer structure unit includes a lattice energy-absorbing core layer and a skin. The outer shell flap has a sandwich layer for accommodating the lattice energy-absorbing core layer. The skin wraps around the outer shell flap. The lattice energy-absorbing core layer adopts one of the following: a beetle-inspired curved rib lattice structure, a chiral nested hexagonal structure, and a hexagonal FBCC structure. Through the differentiated design of the three lattice energy-absorbing core layers with biomimetic lattice configuration, graded energy absorption from low energy level to high energy level is achieved. The three work together to form a muscle simulation system with adjustable mechanical properties and graded energy matching. The parameters of the lattice energy-absorbing core layer can be customized according to the mechanical characteristics of the target muscle part.

[0007] Preferably, each active link is rotatably provided with a driven link via a pin, and the end of the driven link away from the active link slides with a linear groove on the adjacent outer shell flap via a pin.

[0008] As a preferred design, the steps for the beetle-inspired curved rib lattice structure are as follows: First, draw a semi-elliptical curve with a major semi-axis of 4mm and a minor semi-axis of 2.5mm on the front reference plane. The two endpoints of the semi-elliptical curve are C and D. Use the semi-elliptical curve as the path and a circle with a diameter of 0.4mm as the outline to scan and obtain solid one. Draw a straight line AB parallel to the minor axis and 2.2mm away from the minor axis on the front reference plane. Draw a reference plane 1 perpendicular to the front reference plane through the straight line AB. Mirror copy the solid 1 about the reference plane 1 to obtain the intersecting symmetrical double elliptical curved rib solid. The double elliptical rib solid is arrayed once along the major semi-elliptical curve with an array angle of 90° to obtain an annular elliptical rib group. Next, draw circle one with line segment CD as the diameter, and scan with circle one as the path and circle with a diameter of 0.4mm as the outline to generate annulus one; after mirroring and copying annulus one about the reference plane one, the biomimetic elliptical curved rib basic unit cell solid is obtained. Finally, the biomimetic elliptical curved rib basic unit cell entities are arrayed along the x-axis, y-axis and z-axis directions respectively. The array spacing along the x-axis and y-axis directions is 5.25 mm, and the array spacing along the z-axis direction is 4.4 mm, finally obtaining the beetle-like curved rib lattice structure.

[0009] As a preferred approach, the design steps for the chiral nested hexagonal structure are as follows: First, draw a regular hexagon 1 with a side length of 4.6mm on the front reference plane. The six vertices of the regular hexagon 1 are A, B, C, D, E, and F. Draw a regular hexagon 2 at equal intervals of 0.4mm inside the regular hexagon 1. Extrude the regular hexagon 1 and regular hexagon 2 by 0.4mm to obtain solid 2. Next, connect the midpoints of the six sides of regular hexagon one in sequence to obtain regular hexagon three. The six vertices of regular hexagon three are a, b, c, d, e, and f. Then, connect the midpoints of the six sides of regular hexagon two in sequence to obtain regular hexagon four. Extrude 0.4mm using regular hexagon three and regular hexagon four as sketches to obtain a single-layer hexagonal frame solid. Create a reference plane two that is parallel to the front reference plane and 2.3mm away from it. Mirror the single-layer hexagonal frame entity about the reference plane two to obtain two single-layer hexagonal frame entities that are parallel to each other. Then connect point D of the upper single-layer hexagonal frame entity with point C of the lower single-layer hexagonal frame entity to obtain line segment one. Then connect point d of the upper single-layer hexagonal frame entity with point e of the lower single-layer hexagonal frame entity to obtain line segment two. Use line segment one and line segment two as paths and circles as contours to scan and generate two ribs one. Then use a straight line that is perpendicular to the front reference plane and passes through the center of the regular hexagon one as the axis of rotation and array the two ribs one in a circle 5 times with an array angle of 60° to obtain entity three. Create another reference plane three that is parallel to the front reference plane and is 0.2mm away from the front reference plane. Mirror the solid three with respect to the reference plane three to obtain an axially symmetric chiral nested hexagonal unit cell solid. Finally, the chiral nested hexagonal unit cells are arrayed along the x-axis and y-axis directions respectively, with an array spacing of 8mm along the x-axis and y-axis directions, to obtain the chiral nested hexagonal structure.

[0010] As a preferred design, the steps for the hexagonal FBCC structure are as follows: First, following the design steps of the chiral nested hexagonal structure, two single-layer hexagonal frame entities with parallel top and bottom are obtained; Connect point D of the upper single-layer hexagonal frame entity to point C of the lower single-layer hexagonal frame entity to obtain line segment three. Then connect point C of the upper single-layer hexagonal frame entity to point D of the lower single-layer hexagonal frame entity to obtain line segment four. Then connect point D of the upper single-layer hexagonal frame entity to point B of the lower single-layer hexagonal frame entity to obtain line segment five. Using line segment three and line segment four as paths, scan with a rectangle of length 0.4mm and width 0.3mm as the outline to generate two ribs two. Then using line segment five as the path and a circle as the outline, scan to generate one rib three. Finally, using a straight line perpendicular to the front reference plane and passing through the center of regular hexagon one as the rotation axis, circle the two ribs two and one rib three five times with an array angle of 60° to obtain the FBCC basic unit cell entity. The basic unit cell of FBCC is arrayed along the x-axis, y-axis and z-axis respectively. The array spacing along the x-axis and y-axis is 8mm, and the array spacing along the z-axis is 5mm, finally obtaining a hexagonal FBCC structure.

[0011] As a preferred option, the lattice energy-absorbing core layer and the outer shell flap are integrally formed using additive manufacturing technology.

[0012] The present invention has the following beneficial effects: This invention utilizes a mechanically coordinated drive system of forward and reverse ball screws and an X-type scissor lift unit to precisely convert the rotational motion of a servo motor into the radial expansion and axial contraction of the outer shell flaps, accurately simulating the active tension and passive stretching of muscles during a collision. Compared to pneumatic or hydraulic solutions, this all-mechanical structure offers advantages such as rapid response, high control precision, and no risk of leakage. It avoids the instability of fluid components under high-speed impact, significantly improving the bio-simulation of the dummy and the reliability of test data.

[0013] This invention integrates a buffer structure unit consisting of a lattice energy-absorbing core layer and a skin into the outer shell flap interlayer and surface. It employs novel energy-absorbing buffer structures (a beetle-inspired curved-rib lattice structure, a chiral nested hexagonal structure, and a hexagonal FBCC structure), integrally formed through additive manufacturing. This structure efficiently absorbs energy during collisions through cellular plastic deformation, possessing excellent energy absorption capacity and adjustable mechanical properties, enabling customized design of graded energy dissipation and localized buffering characteristics.

[0014] This invention uses forward and reverse ball screws to drive two screw nuts to move synchronously, which in turn drives multiple sets of parallel X-shaped scissor units to swing in a coordinated manner, causing the outer shell flaps to expand or contract evenly, accurately replicating the physiological characteristics of muscle contraction and relaxation. This design has high transmission efficiency and good motion synchronization, avoiding stress concentration caused by asynchronous operation of multiple units, and significantly improving the consistency of the device's movements and long-term operational reliability.

[0015] This invention effectively overcomes the technical challenges of complex structure, control lag, and unstable impact response in traditional dummy muscle simulation. It achieves joint simulation of active muscle contraction force and passive impedance characteristics, providing a highly realistic testing method for injury risk assessment of occupants in unconventional seating positions in driving scenarios. It significantly improves the adaptability and data reliability of collision dummies under complex working conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the end cap, outer shell flap, and positive and negative tooth ball screw in this invention; Figure 3 This is a schematic diagram of the lead screw nut and the active connecting rod in this invention; Figure 4 This is a schematic diagram of the structure of the present invention in its contracted state; Figure 5 This is a schematic diagram of the structure of the present invention in its relaxed state; Figure 6 This is a flowchart illustrating the design process of the beetle-inspired curved rib lattice structure of the present invention. Figure 7 This is a flowchart illustrating the design process of the chiral nested hexagonal structure of the present invention. Figure 8 This is a flowchart illustrating the design process of the hexagonal FBCC structure of the present invention.

[0017] In the diagram: 1, end cap; 2, forward and reverse toothed ball screw; 3, screw nut; 4, outer shell flap; 5, driving link; 6, driven link; 7, pin; 8, lattice energy-absorbing core layer. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0020] Embodiments of the present invention: refer to Figures 1 to 5A mechanical muscle device for a car crash test dummy includes an end cap 1, a ball screw 2 with reverse teeth and a screw nut 3, outer shell flaps 4, a drive link 5, a pin 7, and a buffer structure unit. Each end of the ball screw 2 has an end cap 1, which passes through and is rotatably connected to the end cap 1, forming the support frame of the device. Four symmetrical outer shell flaps 4 are rotatably mounted on the end cap 1 via the pin 7. Each outer shell flap 4 has a drive link 5 hinged to its inner side via a hinged support. The four drive links 5... A common connection is a lead screw nut 3, and the active connecting rod 5 is hinged to the lead screw nut 3. The ball screw 2 with positive and negative threads is provided with positive and negative thread sections. The two lead screw nuts 3 are threaded to the positive and negative thread sections respectively. The two lead screw nuts 3 are symmetrically arranged. The ball screw 2 with positive and negative threads is connected to an external servo drive motor through a coupling to realize precise input of rotational motion. The external servo drive motor can be driven by the controller inside the dummy according to the preset program based on the collision conditions or real-time sensor signals to realize the simulation of active muscle tension. The buffer structure unit includes a lattice energy-absorbing core layer 8 and a skin. The outer shell petal 4 is provided with a sandwich for accommodating the lattice energy-absorbing core layer 8. The skin wraps around the outside of the outer shell petal 4. The lattice energy-absorbing core layer 8 and the outer shell petal 4 are integrally formed by additive manufacturing technology. The lattice energy-absorbing core layer 8 adopts one of the following: beetle-inspired curved rib lattice structure, chiral nested hexagonal structure, and hexagonal FBCC structure. Under collision load, it can efficiently absorb impact energy through cellular plastic deformation. When the forward and reverse toothed ball screw 2 rotates, the two screw nuts 3 can move synchronously in opposite directions or in a straight line along the axial direction. This forward and reverse toothed design ensures the symmetry of the driving force and the synchronization of the movement, avoiding the phenomenon of uneven load. The outer shell 4 is a circumferentially evenly distributed spindle-shaped split structure. Multiple outer shell 4 pieces are used to form a spindle shape that resembles a muscle. The outer skin covering the outer shell 4 is a flexible skin. This flexible skin is made of thermoplastic polyurethane elastomer (TPU) material and is firmly wrapped with the outer shell 4 through secondary injection molding or hot pressing. It is used to simulate the real touch and appearance of human muscles, and at the same time plays a role in protecting the internal structure, buffering minor impacts and improving wear resistance. The outer shell 4 is filled inside the collision dummy. When the forward and reverse toothed ball screw 2 rotates, the outer shell 4 does not rotate relative to the collision dummy.

[0021] Each active link 5 is rotatably mounted with a driven link 6 via a pin 7. The end of the driven link 6 away from the active link 5 slides into a linear groove on the adjacent outer shell flap 4 via the pin 7. The active link 5 and the driven link 6 together form an X-shaped scissor unit. Multiple sets of X-shaped scissor units are distributed in parallel on the same lead screw nut 3. As the lead screw nut 3 moves axially, all X-shaped scissor units swing synchronously, converting the linear motion of the lead screw nut 3 into the radial expansion or contraction and axial length change of the outer shell flap 4, thereby simulating the physiological characteristics of muscle contraction and relaxation.

[0022] like Figure 6As shown, the design steps for the beetle-inspired curved rib lattice structure are as follows: First, draw a semi-elliptical curve with a major semi-axis of 4mm and a minor semi-axis of 2.5mm on the front reference plane. The two endpoints of the semi-elliptical curve are C and D. Use the semi-elliptical curve as the path and a circle with a diameter of 0.4mm as the outline to scan and obtain solid one. Draw a straight line AB parallel to the minor axis and 2.2mm away from the minor axis on the front reference plane. Draw a reference plane 1 perpendicular to the front reference plane through the straight line AB. Mirror copy the solid 1 about the reference plane 1 to obtain the intersecting symmetrical double elliptical curved rib solid. The double elliptical rib solid is arrayed once along the major semi-elliptical curve with an array angle of 90° to obtain an annular elliptical rib group. Next, draw circle one with line segment CD as the diameter, and scan with circle one as the path and circle with a diameter of 0.4mm as the outline to generate annulus one; after mirroring and copying annulus one about the reference plane one, the biomimetic elliptical curved rib basic unit cell solid is obtained. Finally, the biomimetic elliptical curved rib basic unit cell entities are arrayed along the x-axis, y-axis and z-axis directions respectively. The array spacing along the x-axis and y-axis directions is 5.25 mm, and the array spacing along the z-axis direction is 4.4 mm, finally obtaining the beetle-like curved rib lattice structure.

[0023] The beetle-inspired curved-rib lattice structure possesses low stiffness and high elasticity, making it suitable for low-energy impact conditions (less than 500J). In low-speed collisions or active muscle contraction simulations, the beetle-inspired curved-rib lattice structure primarily absorbs energy through elastic bending deformation, enabling rapid response and recovery to its original shape. This makes it suitable for simulating low-intensity active muscle contraction under pre-tension conditions. Its energy absorption density per unit volume is approximately 10–15 MJ / m³, and the deformation process is primarily linear elastic, making it suitable for precise mechanical simulations of small-mass areas such as the neck and upper limbs.

[0024] like Figure 7 As shown, the design steps for a chiral nested hexagonal structure are as follows: First, draw a regular hexagon 1 with a side length of 4.6mm on the front reference plane. The six vertices of the regular hexagon 1 are A, B, C, D, E, and F. Draw a regular hexagon 2 at equal intervals of 0.4mm inside the regular hexagon 1. Extrude the regular hexagon 1 and regular hexagon 2 by 0.4mm to obtain solid 2. Next, connect the midpoints of the six sides of regular hexagon one in sequence to obtain regular hexagon three. The six vertices of regular hexagon three are a, b, c, d, e, and f. Then, connect the midpoints of the six sides of regular hexagon two in sequence to obtain regular hexagon four. Extrude 0.4mm using regular hexagon three and regular hexagon four as sketches to obtain a single-layer hexagonal frame solid. Create a reference plane two that is parallel to the front reference plane and 2.3mm away from it. Mirror the single-layer hexagonal frame entity about the reference plane two to obtain two single-layer hexagonal frame entities that are parallel to each other. Then connect point D of the upper single-layer hexagonal frame entity with point C of the lower single-layer hexagonal frame entity to obtain line segment one. Then connect point d of the upper single-layer hexagonal frame entity with point e of the lower single-layer hexagonal frame entity to obtain line segment two. Use line segment one and line segment two as paths and circles as contours to scan and generate two ribs one. Then use a straight line that is perpendicular to the front reference plane and passes through the center of the regular hexagon one as the axis of rotation and array the two ribs one in a circle 5 times with an array angle of 60° to obtain entity three. Create another reference plane three that is parallel to the front reference plane and is 0.2mm away from the front reference plane. Mirror the solid three with respect to the reference plane three to obtain an axially symmetric chiral nested hexagonal unit cell solid. Finally, the chiral nested hexagonal unit cells are arrayed along the x-axis and y-axis directions respectively, with an array spacing of 8mm along the x-axis and y-axis directions, to obtain the chiral nested hexagonal structure.

[0025] The chiral nested hexagonal structure, through a graded stiffness response mechanism, is suitable for medium-energy impact conditions (greater than or equal to 500 J and less than 1500 J). Under moderate-level impact loads, the outer hexagonal frame (i.e., solid two) first undergoes elastic buckling, followed by the embedded structure gradually participating in energy absorption through torsional and bending deformations, exhibiting a distinct plateau stress zone. This structure can reduce the peak load by approximately 30%, with an energy absorption density of 20–25 MJ / m³, making it suitable for simulating the passive resistance behavior of muscles in areas such as the chest and abdomen under moderate-intensity impacts.

[0026] like Figure 8 As shown, the design steps for the hexagonal FBCC structure are as follows: First, following the design steps of the chiral nested hexagonal structure, two single-layer hexagonal frame entities with parallel top and bottom are obtained; Connect point D of the upper single-layer hexagonal frame entity to point C of the lower single-layer hexagonal frame entity to obtain line segment three. Then connect point C of the upper single-layer hexagonal frame entity to point D of the lower single-layer hexagonal frame entity to obtain line segment four. Then connect point D of the upper single-layer hexagonal frame entity to point B of the lower single-layer hexagonal frame entity to obtain line segment five. Using line segment three and line segment four as paths, scan with a rectangle of length 0.4mm and width 0.3mm as the outline to generate two ribs two. Then using line segment five as the path and a circle as the outline, scan to generate one rib three. Finally, using a straight line perpendicular to the front reference plane and passing through the center of regular hexagon one as the rotation axis, circle the two ribs two and one rib three five times with an array angle of 60° to obtain the FBCC basic unit cell entity. The basic unit cell of FBCC is arrayed along the x-axis, y-axis and z-axis respectively. The array spacing along the x-axis and y-axis is 8mm, and the array spacing along the z-axis is 5mm, finally obtaining a hexagonal FBCC structure.

[0027] The hexagonal FBCC structure possesses high strength and high energy absorption density, making it suitable for high-energy impact conditions (greater than or equal to 1500J and less than 3000J). Under high-energy impact, the support ribs (i.e., rib two and rib three) sequentially undergo three stages: elastic buckling, plastic hinge formation, and cell wall folding, achieving graded crushing and energy dissipation. Its peak load suppression capability can reach over 40%, and its energy absorption density per unit volume is as high as 30–35 MJ / m³, making it suitable for simulating the high-intensity passive buffering and active contraction response of large-mass areas such as the lower limbs and hips in strong collisions.

[0028] The working principle of all the content in the above embodiments is as follows: When simulating active muscle contraction (such as pre-collision tension), the servo motor drives the forward and reverse toothed ball screws 2 to rotate forward, and the two screw nuts 3 move towards each other. The screw nuts 3 push the active connecting rod 5 inward around its hinge point with the outer shell flap 4, while the driven connecting rod 6 slides in the linear groove and supports the radial contraction of the outer shell flap 4. Due to the parallel action of multiple X-shaped scissor units, multiple outer shell flaps 4 contract radially and uniformly, such as... Figure 4 The diagram shows a contracted state. When the forward and reverse ball screws 2 rotate in opposite directions, the screw nuts 3 move away from each other, pulling the drive link 5 and causing the outer shell flap 4 to expand outward, as shown. Figure 5 The dummy recovers to its relaxed state as shown. The rotation of the drive screw (positive and negative toothed ball screw 2) is precisely converted into the push-pull motion of the linkage mechanism (X-type scissor unit), achieving a mechanical simulation of muscle contraction and relaxation. This effectively improves the bio-simulation of the collision dummy and the reliability of test data while ensuring a compact structure and rapid response. At the moment of impact, if the dummy's limbs are subjected to external impact, the buffer structure unit in the outer shell flap 4 absorbs energy through the plastic deformation of the lattice energy-absorbing core layer 8, simulating the passive impedance characteristics of muscle soft tissue, thereby buffering the impact force and protecting the internal mechanical structure.

[0029] In summary, the three types of lattice energy-absorbing core layers 8, through differentiated designs of biomimetic lattice configurations, achieve graded energy absorption from low to high energy levels: the beetle-inspired curved-rib lattice structure, primarily based on elastic deformation, is suitable for low-intensity active contraction simulation; the chiral nested hexagonal structure, through graded stiffness response, exhibits a stable plateau stress zone under mid-energy impacts; and the hexagonal FBCC structure, through a step-by-step crushing mechanism, achieves efficient energy dissipation in high-energy impacts. These three elements work together to form a muscle simulation system with adjustable mechanical properties and graded energy matching, significantly improving the biosimulation and testing accuracy of the collision dummy under various conditions.

[0030] This invention can precisely control the amount of contraction by adjusting the rotation angle of the servo motor, thereby simulating the tension of different muscle groups under different working conditions. At the same time, the eight parameters of the lattice energy-absorbing core layer of the buffer structure unit can be customized according to the mechanical characteristics of the target muscle part (such as the neck, chest, and lower limbs). For example, the size, rod diameter, or material of the cell unit (bionic elliptical curved rib basic unit cell, chiral nested hexagonal unit cell, FBCC basic unit cell) can be changed to match the stress-strain curves under different strain rates, thereby achieving graded dissipation of collision energy.

[0031] This invention, through its fully mechanical structure, avoids the inherent leakage and response lag problems of pneumatic and hydraulic solutions, and boasts advantages such as compact structure, high control precision, good motion synchronization, and stable impact response. The cooperation between the X-type scissor lift unit and the forward and reverse toothed ball screw 2 ensures the consistency of multi-unit actions and avoids stress concentration. The buffer structure unit integrated on the outer shell flap 4 not only enhances the biomimetic accuracy but also achieves lightweighting and adjustable mechanical properties through additive manufacturing, significantly improving the adaptability and data reliability of the crash dummy in complex testing scenarios such as unconventional sitting postures and active pretensioning seat belt matching.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mechanical muscle device for a car crash test dummy, characterized in that, The system includes an end cap (1), a ball screw (2) with positive and negative teeth, a screw nut (3), a housing flap (4), an active connecting rod (5), a pin (7), and a buffer structure unit. Both ends of the ball screw (2) with positive and negative teeth are rotatably equipped with an end cap (1). The end cap (1) is rotatably equipped with four symmetrical housing flaps (4) through the pin (7). An active connecting rod (5) is hinged to the inner side of each housing flap (4). The four active connecting rods (5) are connected together by a screw nut (3). The active connecting rod (5) is hinged to the screw nut (3). The ball screw (2) with positive teeth is provided with a positive tooth section and a negative tooth section. The two screw nuts (3) are threadedly engaged with the positive tooth section and the negative tooth section, respectively. The ball screw (2) with positive teeth is connected to an external drive motor through a coupling. The buffer structure unit includes a lattice energy-absorbing core layer (8) and a skin. The outer shell flap (4) is provided with a sandwich for accommodating the lattice energy-absorbing core layer (8). The skin is wrapped around the outside of the outer shell flap (4). The lattice energy-absorbing core layer (8) adopts one of the following: a beetle-inspired curved rib lattice structure, a chiral nested hexagonal structure, and a hexagonal FBCC structure. Through the differentiated design of the three lattice energy-absorbing core layers with biomimetic lattice configuration, graded energy absorption from low energy level to high energy level is achieved. The three work together to form a muscle simulation system with adjustable mechanical properties and graded energy matching. The parameters of the lattice energy-absorbing core layer can be customized according to the mechanical properties of the target muscle part.

2. The mechanical muscle device for a car crash dummy according to claim 1, characterized in that, Each active link (5) is rotatably provided with a driven link (6) via a pin (7). The end of the driven link (6) away from the active link (5) is slidably engaged with the linear groove on the adjacent outer shell flap (4) via the pin (7).

3. The mechanical muscle device for a car crash dummy according to claim 1, characterized in that, The design steps for the beetle-inspired curved-rib lattice structure are as follows: First, draw a semi-elliptical curve with a major semi-axis of 4mm and a minor semi-axis of 2.5mm on the front reference plane. The two endpoints of the semi-elliptical curve are C and D. Use the semi-elliptical curve as the path and a circle with a diameter of 0.4mm as the outline to scan and obtain solid one. Draw a straight line AB parallel to the minor axis and 2.2mm away from the minor axis on the front reference plane. Draw a reference plane 1 perpendicular to the front reference plane through the straight line AB. Mirror copy the solid 1 about the reference plane 1 to obtain the intersecting symmetrical double elliptical curved rib solid. The double elliptical rib solid is arrayed once along the major semi-elliptical curve with an array angle of 90° to obtain an annular elliptical rib group. Next, draw circle one with line segment CD as the diameter, and scan with circle one as the path and circle with a diameter of 0.4mm as the outline to generate annulus one; after mirroring and copying annulus one about the reference plane one, the biomimetic elliptical curved rib basic unit cell solid is obtained. Finally, the biomimetic elliptical curved rib basic unit cell entities are arrayed along the x-axis, y-axis and z-axis directions respectively. The array spacing along the x-axis and y-axis directions is 5.25 mm, and the array spacing along the z-axis direction is 4.4 mm, finally obtaining the beetle-like curved rib lattice structure.

4. The mechanical muscle device for a car crash dummy according to claim 1, characterized in that, The design steps for a chiral nested hexagonal structure are as follows: First, draw a regular hexagon 1 with a side length of 4.6mm on the front reference plane. The six vertices of the regular hexagon 1 are A, B, C, D, E, and F. Draw a regular hexagon 2 at equal intervals of 0.4mm inside the regular hexagon 1. Extrude the regular hexagon 1 and regular hexagon 2 by 0.4mm to obtain solid 2. Next, connect the midpoints of the six sides of regular hexagon one in sequence to obtain regular hexagon three. The six vertices of regular hexagon three are a, b, c, d, e, and f. Then, connect the midpoints of the six sides of regular hexagon two in sequence to obtain regular hexagon four. Extrude 0.4mm using regular hexagon three and regular hexagon four as sketches to obtain a single-layer hexagonal frame solid. Create a reference plane two that is parallel to the front reference plane and 2.3mm away from it. Mirror the single-layer hexagonal frame entity about the reference plane two to obtain two single-layer hexagonal frame entities that are parallel to each other. Then connect point D of the upper single-layer hexagonal frame entity with point C of the lower single-layer hexagonal frame entity to obtain line segment one. Then connect point d of the upper single-layer hexagonal frame entity with point e of the lower single-layer hexagonal frame entity to obtain line segment two. Use line segment one and line segment two as paths and circles as contours to scan and generate two ribs one. Then use a straight line that is perpendicular to the front reference plane and passes through the center of the regular hexagon one as the axis of rotation and array the two ribs one in a circle 5 times with an array angle of 60° to obtain entity three. Create another reference plane three that is parallel to the front reference plane and is 0.2mm away from the front reference plane. Mirror the solid three with respect to the reference plane three to obtain an axially symmetric chiral nested hexagonal unit cell solid. Finally, the chiral nested hexagonal unit cells are arrayed along the x-axis and y-axis directions respectively, with an array spacing of 8mm along the x-axis and y-axis directions, to obtain the chiral nested hexagonal structure.

5. The mechanical muscle device for a car crash dummy according to claim 4, characterized in that, The design steps for a hexagonal FBCC structure are as follows: First, following the design steps of the chiral nested hexagonal structure, two single-layer hexagonal frame entities with parallel top and bottom are obtained; Connect point D of the upper single-layer hexagonal frame entity to point C of the lower single-layer hexagonal frame entity to obtain line segment three. Then connect point C of the upper single-layer hexagonal frame entity to point D of the lower single-layer hexagonal frame entity to obtain line segment four. Then connect point D of the upper single-layer hexagonal frame entity to point B of the lower single-layer hexagonal frame entity to obtain line segment five. Using line segment three and line segment four as paths, scan with a rectangle of length 0.4mm and width 0.3mm as the outline to generate two ribs two. Then using line segment five as the path and a circle as the outline, scan to generate one rib three. Finally, using a straight line perpendicular to the front reference plane and passing through the center of regular hexagon one as the rotation axis, circle the two ribs two and one rib three five times with an array angle of 60° to obtain the FBCC basic unit cell entity. The basic unit cell of FBCC is arrayed along the x-axis, y-axis and z-axis respectively. The array spacing along the x-axis and y-axis is 8mm, and the array spacing along the z-axis is 5mm, finally obtaining a hexagonal FBCC structure.

6. The mechanical muscle device for a car crash dummy according to claim 1, characterized in that, The lattice energy-absorbing core layer (8) and the outer shell petal (4) are integrally formed by additive manufacturing technology.

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