Corrugated sandwich design method and bidirectional energy absorption structure

Abstract

The invention discloses a corrugated sandwich bidirectional energy absorption structure and a design method. The corrugated sandwich bidirectional energy absorption structure comprises a unit composed of periodic corrugated curved walls and a sandwich body composed of an upper panel and a lower panel. Controllable buckling and multi-stage collapsing of the corrugated wall plate in the loading process are achieved through preset curvature, a node transition structure and wall thickness distribution. Independent but mutually coupled energy dissipation paths are formed in the units in the two main directions, so that the structure can keep a stable energy absorption mode under the working conditions of compression, shearing and composite impact; according to the structure, a partition triggering mechanism, local plastic hinge control and a shape constraint effect are introduced in design, specific energy absorption, platform stress stability and structure failure resistance are remarkably improved, the structure can be widely applied to traffic equipment collision prevention, aerospace protection, electromechanical equipment buffering, building disaster reduction and other scenes, and light weight and efficient energy absorption are both achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sandwich energy-absorbing structures, and particularly relates to a corrugated sandwich design method and a bidirectional energy-absorbing structure. BACKGROUND

[0002] The existing composite sandwich energy-absorbing structure is widely used in high-end equipment, but there are problems such as insufficient structural reliability, complex manufacturing process, and limited bidirectional energy-absorbing capacity. The conventional corrugated core is prone to stress concentration at the ridge line, and the fibers are easily damaged and the resin is uneven when the composite is formed at the sharp corner, resulting in attenuation of mechanical properties; the traditional structure is stable in crushing, but the peak energy absorption is low, which is difficult to meet the high impact scene; at the same time, the hot-pressing die is complex, the wall thickness consistency is poor, and the batch manufacturing is limited. SUMMARY

[0003] The application provides a designable corrugated sandwich bidirectional energy-absorbing structure, which optimizes the core configuration and manufacturing process, aims to improve the structural reliability, simplify the manufacturing process, realize the horizontal and vertical bidirectional energy-absorbing to enhance the energy-absorbing performance, and meet the customized needs of different scenes; has the characteristics of the sandwich structure that is easy to form, high reliability, and can realize horizontal and vertical bidirectional energy-absorbing, so as to comprehensively improve the energy-absorbing density, structural stability, manufacturing consistency and application range;

[0004] A corrugated sandwich design method, comprising the following steps:

[0005] The core plate is a continuous single-curvature corrugated composite material plate, and the equivalent mechanical parameters are calculated and designed through periodic sandwich units;

[0006] The material flexibility matrix, angle conversion matrix and equivalent modulus calculation model are established, and the equivalent modulus of the sandwich structure in at least two orthogonal directions is obtained The equivalent modulus is obtained, the corresponding direction energy-absorbing deformation is determined, and the sandwich structure meets the energy-absorbing target under external load;

[0007] An energy-absorbing model is constructed , and based on the number of core plates m, the number of corrugations n, the thickness t of the core plate and the equivalent modulus , the deformation under the target energy-absorbing amount is calculated , which is used to determine the energy-absorbing displacement target of the sandwich structure, wherein The formula is as follows:

[0008]

[0009] Wherein, the sandwich structure forms a corrugated energy-absorbing structure, the sandwich structure comprises The single-core plate is bonded by blocks, the thickness of the single-core plate is , and the length is comprising corrugations;

[0010] is the total energy absorbed during the compression deformation process:

[0011]

[0012] wherein, is the cushioning deformation displacement of the sandwich structure;

[0013] is the instantaneous load when the compression displacement of the sandwich structure is

[0014] The technical solution aims at the problems of the traditional sandwich structure, such as insufficient bidirectional energy absorption consistency, structure reliability affected by uncontrollable waveforms, complex manufacturing process and difficult parameterized design, and proposes a design method of a designed corrugated sandwich structure bidirectional energy absorption structure; the scheme takes a continuous single-curvature corrugated surface as a basic configuration, establishes an explicit engineering parameter system through a periodic unit mechanical equivalent model, realizes a calculable link of "structure shape-equivalent modulus-energy absorption displacement-target energy absorption", and changes the energy absorption performance from an empirical formula design depending on experiments to a predictable and controllable parameterized design.

[0015] The continuous single-curvature S-shaped corrugated structure is adopted as a basic surface unit, so that the sandwich structure forms stable and continuous buckling paths in two orthogonal directions, laying a foundation for bidirectional or multidirectional energy absorption;

[0016] A calculation model of material flexibility matrix, angle conversion matrix and equivalent modulus is established, so that the structure has a quantifiable equivalent mechanical response under external load; secondly, an energy absorption displacement calculation method based on an energy absorption model is introduced, and the deformation amount required in the target direction is directly determined through controllable parameters such as , so as to realize quantitative design of the energy absorption target;

[0017] The structure configuration can be parameterized and controlled, the mechanical properties can be predicted, the energy absorption deformation amount can be designed as needed, and the manufacturing method can realize consistent mass production through the lamination of composite corrugated plates; bidirectional energy absorption is naturally obtained through orthogonal design of equivalent modulus, and the structure can maintain a stable energy absorption mode in the horizontal and vertical directions;

[0018] ​​​​Significantly improve the bidirectional energy absorption density and stability; Through the establishment of equivalent model and energy model to realize the design and pre-evaluation of energy absorption performance; The continuous structure surface is easy to process and form, and the bonded composite corrugated plate simplifies the manufacturing process and improves the structural reliability and repeatability; Different application scenarios can be customized by adjusting the number of corrugations n, plate thickness t, and unit number m.

[0019] The technical scheme provided by the application also has the following technical features:

[0020] Preferably, in an embodiment of the application, the equivalent modulus Including three directions, :

[0021]

[0022]

[0023]

[0024] The intermediate parameters in the formula are as follows:

[0025]

[0026]

[0027]

[0028]

[0029] Based on the compliance matrix of the orthotropic anisotropic material:

[0030]

[0031] Convert the compliance matrix Into the engineering elastic constant expression to obtain the value of :

[0032]

[0033] Wherein:

[0034] , , The elastic modulus of the material in the 1, 2, and 3 directions, wherein:

[0035] 1 direction is the fiber direction of the core plate, the axial length extension direction;

[0036] 2 direction is perpendicular to the fiber of the core plate, the transverse width extension direction;

[0037] 3. The direction is perpendicular to the plane of the unidirectional core board, and the normal direction of the fiber lay-up plane;

[0038] For stress in When acting in a direction direction and The negative value of the ratio of strain in the direction, Values ​​are 1, 2, and 3;

[0039] For the shear modulus of the 2-3, 3-1, 1-2 plane;

[0040] The angle of the wavy shape is The stress-strain relationship at the point is:

[0041]

[0042]

[0043]

[0044]

[0045] in:

[0046] This is the strain-displacement matrix;

[0047] Displacement in the X-axis direction;

[0048] Displacement in the Y-axis direction;

[0049] Displacement in the Z-axis direction;

[0050] Displacement in the YZ plane direction;

[0051] Displacement in the XZ plane direction;

[0052] Displacement in the XY plane;

[0053] The stress matrix;

[0054] Normal stress in the X-axis direction;

[0055] Normal stress in the Y-axis direction;

[0056] Normal stress in the Z-axis direction;

[0057] The shear stress is in the YZ plane direction;

[0058] The shear stress is in the XZ plane direction;

[0059] The shear stress is in the XY plane.

[0060] To handle the multiple relationship between engineering shear strain and tensor shear strain:

[0061]

[0062] The angle transformation matrix is ​​determined based on the ripple shape:

[0063]

[0064] In the formula:

[0065]

[0066]

[0067] The sandwich structure is regarded as an array structure of individual cells, and each bonding part is regarded as a symmetrical constraint boundary. The deformation after loading is calculated, and the energy absorption displacement is determined in combination with the material strength.

[0068] Assuming the energy is constant during the energy absorption deformation process, i.e., F and Decoupling, F and It's irrelevant, I don't follow. change.

[0069] Preferably, in one embodiment of this application, the parameters of the curved surface configuration include at least the fold height A and the fold span L, and are adjusted... The ratio allows the energy absorption performance of the sandwich structure to be adjusted in both the lateral and vertical directions, enabling the sandwich structure to match the impact conditions of the target scenario.

[0070] The balance parameters between peak energy absorption, specific energy absorption, and structural weight include: number of stacked layers, core material thickness, and number of corrugations.

[0071] Preferably, in one embodiment of this application, the number of corrugations n and the number of stacked units m are adjusted to control the distribution of peak energy absorption and specific energy absorption in different directions, so that the residual load-bearing capacity of the sandwich structure after impact resistance meets the design target.

[0072] Preferably, in one embodiment of this application, the surface geometry design parameters of the core board are defined as follows: fold height A and fold span L, and absorption capacity distribution ratio. .

[0073] Preferably, in one embodiment of this application, the sandwich structure is composed of at least three core plates of the same shape connected to form a box-type cell array. The connection method is adhesive bonding, mechanical connection, or a combination thereof, to ensure the repeatability of the manufacturing process and the convenience of modular assembly.

[0074] Preferably, in one embodiment of this application, the corrugated single-curved panel structure of the core board is obtained through a positive mold laying and curing process, and the geometric design parameters are defined including the settings for the layup angle, layup sequence and layup symmetry.

[0075] Preferably, in one embodiment of this application, the pleated core of the sandwich structure is a periodic corrugated single-curved panel, with the ends folded over so as to be bonded and attached to the panel during assembly;

[0076] The core board includes curved surfaces and layups; core board manufacturing is based on corrugated male mold layup and curing.

[0077] The corrugated pleated unit of the sandwich structure is formed by stacking three or more layers of core board.

[0078] The surface geometry design parameters of the core board are defined as follows: fold height A and fold span L, and absorption capacity distribution ratio. .

[0079] Preferably, in one embodiment of this application, a corrugated sandwich bidirectional energy-absorbing structure includes a core plate arranged periodically, the core plate being a regular cell array; the core plate is provided with a pleated configuration with a continuous curvature distribution.

[0080] The core board adopts a laminated structure, consisting of at least three reinforcing layers with preset layup angles;

[0081] The core board has a flanged end for bonding with the panel.

[0082] Preferably, in one embodiment of this application, the core board forms a box-type array structure by adhesive bonding, interlocking or mechanical connection, so that each unit cell can maintain coordinated deformation after being loaded;

[0083] The core board comprises at least three stacked core material units that exhibit a progressive folding pattern when compressed and retain residual load-bearing capacity after being crushed.

[0084] Preferably, in one embodiment of this application, the corrugated surface of the core board is provided with a surface with continuously varying curvature, and the core board with variable curvature can also be extended to form a specially customized sandwich structure with different performance at each position.

[0085] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0086] Compared with the prior art, the technical solution of this application has achieved the following technical advancements:

[0087] 1. This application addresses the problem of insufficient bidirectional energy absorption capacity of traditional and pleated sandwich structures. By adopting a core plate with a continuous curved surface configuration, it achieves controllable progressive crushing in both the lateral and vertical directions, overcoming the shortcomings of existing structures with a single energy absorption mode and insufficient peak energy absorption. It achieves the technical effects of designable energy absorption direction, stable peak energy absorption, and improved specific energy absorption.

[0088] 2. This application addresses the problem of early damage caused by stress concentration at the corners of the pleated core. By using a core board formed by continuous single-curved surface and using laminated boards to achieve uniform stress on the curved surface, it overcomes the problems of fiber shearing and uneven resin distribution caused by traditional pleated geometry, and achieves the technical effects of improved structural reliability, stable failure mode and extended service life.

[0089] 3. This application addresses the problem that composite material pleated sandwich cores rely on complex molds and have high molding difficulty. The core plate adopts a laying and curing method based on a corrugated male mold, so that the sandwich structure has a uniform curved surface geometry that can be repeatedly manufactured. This overcomes the high dependence of traditional multi-angle cores on mold precision and demolding process, and achieves the technical effects of simplified manufacturing process, improved molding consistency and reduced production cost.

[0090] 4. This application addresses the problem of sudden failure in existing sandwich structures during crushing. By designing the core plate as a multi-layered, progressively foldable structural unit, it overcomes the defects of sudden load drop caused by abrupt changes and instability in traditional crushing modes, achieving the technical effects of controllable deformation, stable energy absorption process, and residual load-bearing capacity. Attached Figure Description

[0091] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0092] Figure 1 This is a schematic diagram of a bidirectional corrugated energy-absorbing structure according to one embodiment;

[0093] Figure 2 This is a simplified model diagram of a corrugated laminate according to one embodiment;

[0094] Figure 3 This is a schematic diagram of the elastic modulus of a material in different directions according to one embodiment;

[0095] Components in the diagram:

[0096] 1. Panel

[0097] 2. Core board. Detailed Implementation

[0098] The specific embodiments of this application will be further described in detail below with reference to the accompanying drawings. These embodiments are only for illustrating this application and are not intended to limit the invention.

[0099] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0100] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0101] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0102] like Figures 1-2 It should be noted that the final implementation in this application is as follows: Figure 1 The composite structural material, wherein panel 1 is set on the outside and the inside of panel 1 is a sandwich structure, and the sandwich structure is composed of m columns of core plates 1;

[0103] A corrugated sandwich design method includes the following steps:

[0104] The curved surface configuration is a continuous single-curvature corrugated pleated structure. The equivalent mechanical parameters are calculated and designed through the sandwich unit of the periodic curved surface configuration.

[0105] Establish material compliance matrix, angle transformation matrix, and equivalent modulus calculation model to obtain the equivalent modulus of the sandwich structure in at least two orthogonal directions. The equivalent modulus obtained Determine the energy absorption deformation in the corresponding direction so that the sandwich structure meets the energy absorption target under external load;

[0106] Constructing an energy absorption model Based on the number of core plates m, the number of corrugations n, the thickness t of the single-plate core plate, and the equivalent modulus of the sandwich structure. Calculate the deformation of the target under absorbed energy. Used to determine the target energy-absorbing displacement of the sandwich structure, where The formula is as follows:

[0107]

[0108] Among them, the corrugated energy absorption structure includes The corrugated composite board is bonded together with blocks, and the thickness of a single corrugated composite board is [missing information]. , length is Include ripples;

[0109] The total energy absorbed during compression deformation:

[0110]

[0111] in, This serves as a buffer for the deformation displacement of the sandwich structure.

[0112] The compressive displacement of the sandwich structure is Instantaneous load at time;

[0113] Key implementation points: The implementation of this structure is based on a controllable corrugated continuous pleated surface configuration and the stacking and forming of composite corrugated plates. The equivalent modulus is determined according to the target energy absorption. , number of ripples , plate thickness Number of units Parameters; then, based on the compliance matrix and angle transformation matrix, equivalent mechanical solutions are obtained in orthogonal directions; subsequently, the target deformation is calculated using an energy absorption model. As the core control quantity of sandwich structure design; in terms of manufacturing, by bonding several prefabricated corrugated composite panels into an integral sandwich structure, continuous curvature structure can be stably manufactured, consistency can be improved and molding process can be simplified; finally, through parametric design process, the energy absorption performance and structural geometry are one-to-one correspondence is realized, so that the structure has adjustable energy absorption capacity in both horizontal and vertical directions.

[0114] Working principle: The structure is based on the progressive buckling characteristics of continuous corrugated folds under compression, achieving a stable and controllable energy absorption process. During loading, each corrugated unit of the sandwich structure buckles gradually along a predetermined fold path, keeping the load-displacement curve stable and avoiding sudden buckling instability. This is achieved through equivalent modulus... By employing orthogonal solutions, the bending and compressive resistance of a structure under external loads can be quantitatively described, making its bidirectional energy absorption behavior predictable; the energy absorption process follows... The integral model is calculated using structural parameters. The combination of the control over the number and deformation length of the buckling wavebands determines the total absorbed energy and the corresponding deformation. This achieves a clear correlation between the energy absorption target and the structural shape.

[0115] Using continuous single-curvature corrugated pleats as the core configuration, combined with composite corrugated plate stacking and parametric theoretical models, a bidirectional energy absorption capacity, structural stability, and ease of manufacturing, which are difficult to achieve simultaneously in traditional structures, are realized. The implementation path is clear: a mechanical foundation is established through the flexibility matrix and equivalent modulus; the deformation target is determined through an energy model; and geometric parameters are used to achieve the desired results. By adjusting the structure, the energy absorption performance becomes adjustable and designable; ultimately, the system achieves significant improvements in structural reliability, energy absorption density, predictability, and adaptability, providing a parameterized and engineerable technical solution for the design of buffer and protection structures under complex working conditions.

[0116] Specifically, in one embodiment of this application, the equivalent modulus Includes three directions, :

[0117]

[0118]

[0119]

[0120] The intermediate parameters in the formula are as follows:

[0121]

[0122]

[0123]

[0124]

[0125] Here is the compliance matrix based on orthotropic materials:

[0126]

[0127] The softness matrix Converted into an expression of engineering elastic constants, thus obtaining Value:

[0128]

[0129] in:

[0130] , , Let be the elastic modulus of the material in directions 1, 2, and 3;

[0131] 1. The direction is the fiber direction of the core board, the axial length extension direction;

[0132] 2. Fibers perpendicular to the core board in the transverse width extension direction;

[0133] 3. The direction is perpendicular to the plane of the unidirectional core board, and the normal direction of the fiber lay-up plane;

[0134] For stress in When acting in a direction direction and The negative value of the ratio of strain in the direction, Values ​​are 1, 2, and 3;

[0135] For the shear modulus of the 2-3, 3-1, 1-2 plane;

[0136] The angle of the wavy shape is The stress-strain relationship at the point is:

[0137]

[0138]

[0139]

[0140]

[0141] in:

[0142] This is the strain-displacement matrix;

[0143] Displacement in the X-axis direction;

[0144] Displacement in the Y-axis direction;

[0145] Displacement in the Z-axis direction;

[0146] Displacement in the YZ plane direction;

[0147] Displacement in the XZ plane direction;

[0148] Displacement in the XY plane;

[0149] The stress matrix;

[0150] Normal stress in the X-axis direction;

[0151] Normal stress in the Y-axis direction;

[0152] Normal stress in the Z-axis direction;

[0153] The shear stress is in the YZ plane direction;

[0154] The shear stress is in the XZ plane direction;

[0155] The shear stress is in the XY plane.

[0156] To handle the multiple relationship between engineering shear strain and tensor shear strain:

[0157]

[0158] The angle transformation matrix is ​​determined based on the ripple shape:

[0159]

[0160] In the formula:

[0161]

[0162]

[0163] The sandwich structure is regarded as an array structure of individual cells, and each bonding part is regarded as a symmetrical constraint boundary. The deformation after loading is calculated, and the energy absorption displacement is determined in combination with the material strength.

[0164] Assuming the energy is constant during the energy absorption deformation process, i.e., F and Decoupling, F and It's irrelevant, I don't follow. change;

[0165] To address the issues of uncontrollable equivalent mechanical parameters and uneven energy absorption performance in traditional sandwich structures under different loading directions, this paper employs a method based on the equivalent modulus solution characteristics using the orthogonal anisotropic compliance matrix S, the angle transformation matrix T, and the stress-strain transformation relationship to obtain direction-dependent intermediate parameters. To achieve The quantitative design of equivalent moduli in three orthogonal directions overcomes the shortcomings of existing structures where performance can only be determined through a "trial-and-test" approach, making it difficult to design bidirectional energy absorption. This achieves the technical effect of directly inversely calculating structural parameters based on target energy absorption requirements and simultaneously meeting energy absorption demands under external loads. Specifically, in this embodiment, a matrix is ​​used... To address differences in shear strain forms, a matrix is ​​used. Achieve the transformation between the local coordinate system and the global coordinate system, thereby obtaining the corrugated element in any coordinate system. The true flexibility of the location; then, averaging the flexibility along the length L, yields the effective response capability of the sandwich structure under bidirectional or triaxial loading; furthermore, in solving for the energy-absorbing displacement... When the sandwich structure is considered as a periodic cell array, a simplified solution can be achieved by applying symmetrical constraints to the bonding areas, and under the assumption that... and Under decoupling conditions, the target displacement range corresponding to energy absorption can be obtained quickly, making this embodiment calculable, manufacturable, and verifiable in terms of engineering feasibility.

[0166] Specifically, in one embodiment of this application, the parameters of the curved surface configuration include at least the fold height A and the fold span L, and are adjusted... The ratio allows the energy absorption performance of the sandwich structure to be adjusted in both the lateral and vertical directions, enabling the sandwich structure to match the impact conditions of the target scenario.

[0167] The balance parameters between peak energy absorption, specific energy absorption, and structural weight include: the number of stacked layers, core material thickness, and the number of corrugations; adjusting the number of corrugations n and the number of unit stacks m completes the distribution control of peak energy absorption and specific energy absorption in different directions, so that the residual load-bearing capacity of the sandwich structure after impact resistance meets the design objectives; the surface geometry design parameters of the core plate are defined as: fold height A and fold span L, and the energy absorption distribution ratio. ;

[0168] To address the shortcomings of traditional sandwich structures, such as insufficient adjustability in energy absorption direction, unpredictable mechanical response, and low parameter correlation, a curved surface configuration parameter system based on fold height A and fold span L is adopted. This system allows for adjustment of... The ratio enables continuous control of bidirectional energy absorption performance under external loads, overcoming the shortcomings of existing structures that can only be optimized in a limited direction and are difficult to match specific impact scenarios. This achieves the technical effect of customized energy absorption of sandwich structures according to target load conditions. At the same time, by using the number of stacked layers m, core material thickness t, and number of corrugations n as balance adjustment parameters between peak energy absorption, specific energy absorption, and structural mass, in this embodiment, the energy absorption peak distribution in different directions can be established by changing the combination of n and m, so that the structure maintains the necessary residual load-bearing capacity after impact, thereby meeting the design requirements of multiple working conditions.

[0169] Specifically, in one embodiment of this application, the sandwich structure consists of at least three core plates of the same shape connected to form a box-type cell array. The connection method is adhesive bonding, mechanical connection, or a combination thereof to ensure the repeatability of the manufacturing process and the convenience of modular assembly. The corrugated single-curved panel is obtained through a positive mold laying and curing process. The geometric design parameters are defined, including the settings for the layup angle, layup sequence, and layup symmetry. The pleated sandwich core is a periodic corrugated single-curved panel with folded ends for bonding and adhering to the panel during assembly.

[0170] The core board includes curved surfaces and layups; core board manufacturing is based on corrugated male mold layup and curing.

[0171] The corrugated pleated unit of the sandwich structure is formed by stacking three or more layers of core board.

[0172] The surface geometry design parameters of the core board are defined as follows: fold height A and fold span L, and absorption capacity distribution ratio. ;

[0173] To address the issues of poor modular manufacturability, inconvenient assembly, and uncontrollable energy absorption distribution in traditional sandwich structures, this invention employs a box-like cell array structure composed of at least three geometrically identical corrugated single-curved panels bonded together, mechanically connected, or a combination of both. This allows the core material to be repeatedly manufactured and modularly assembled, overcoming the shortcomings of existing monolithic molding structures that struggle to guarantee geometric consistency and have high assembly complexity. This results in high manufacturing robustness and controllable structural precision. In this embodiment, the corrugated single-curved panels are formed using a positive mold laying-curing process. By designing the layup angle, layup sequence, and symmetry, the panels achieve predictable orthogonal anisotropy enhancement in different directions. An end-folding structure ensures the bonding quality between the panels and the core material during assembly, thereby improving the edge stability of the overall sandwich structure. The pleated sandwich unit uses a periodic corrugated single-curved surface, stacked in three or more layers to form an energy-absorbing unit, providing greater controllability during buckling and crushing stages. The pleat height A and span L are used as core geometric parameters of the curved surface, and their ratio... It is used to determine the directional distribution of energy absorption and can be controlled directly during the manufacturing stage through mold design and laying path.

[0174] Specifically, in one embodiment of this application, a corrugated sandwich bidirectional energy-absorbing structure includes a periodically arranged core plate, the core plate being a regular cell array; the core plate is provided with a pleated configuration with a continuous curvature distribution.

[0175] The core board adopts a laminated structure, consisting of at least three reinforcing layers with preset layup angles;

[0176] The core board has a flanged end for bonding and connection with the panel;

[0177] This embodiment employs a periodically arranged core plate to form a regular cell array, and a progressively buckling energy absorption path is formed through a pleated configuration with a continuous curvature distribution. This overcomes the defects of ordinary straight walls, such as sudden buckling under load and single buckling instability direction, achieving the technical effect of adjustable bidirectional energy absorption under external load and more stable load response. In this embodiment, the core plate adopts a laminated structure of at least three layers, and an orthotropic reinforcement system is constructed by pre-setting the layup angle, so that the equivalent modulus of the structure matches the buckling waveform, thereby significantly improving the controllability of the pleats and the energy absorption density during the compression stage. In addition, the corrugated single-curved panel is provided with a flange at the end, so that it forms a larger bonding area and stable boundary constraint conditions when bonded or mechanically combined with the panel, avoiding warping or early failure at the boundary of traditional thin-walled structures.

[0178] Specifically, in one embodiment of this application, the core board forms a box-type array structure by adhesive bonding, interlocking or mechanical connection, so that each unit cell can maintain coordinated deformation after being loaded;

[0179] The core board comprises at least three stacked core material units, exhibits a progressive folding pattern when compressed, and retains residual load-bearing capacity after being crushed.

[0180] To address the issues of traditional sandwich units struggling to maintain coordinated deformation under load, exhibiting abrupt collapse patterns, and insufficient residual load-bearing capacity, this embodiment employs a core plate structure formed by adhesive bonding, interlocking, or mechanical connections to create a box-like array. This allows each cell to achieve synchronous and progressive folding behavior through boundary constraints during loading, overcoming the uneven stress distribution and local instability inherent in ordinary straight walls. The result is a more stable overall structural compression response and higher energy absorption efficiency. In this embodiment, the core plate consists of at least three stacked units, enabling the core material to exhibit a progressive folding pattern of continuous folds under external pressure, preventing instantaneous collapse and maintaining necessary residual load-bearing capacity after collapse to support secondary load requirements. Simultaneously, the corrugated surface features a geometric configuration with continuously varying curvature, allowing the structure to form a controllable deformation path during buckling, effectively dispersing stress concentration and improving energy absorption stability.

[0181] Specifically, in one embodiment of this application, the corrugated surface of the core board is provided with a surface with continuously varying curvature, and the core board with variable curvature can also be extended to form a specially customized sandwich structure with different performance at each position.

[0182] Specifically, in one embodiment of this application, there are existing innovative cases of energy-absorbing structures utilizing multi-layer composite corrugated plates, but these only provide the design concept of multi-layer stacking. The difference in this application is:

[0183] (1) Taking advantage of the material properties of orthogonal anisotropy of composite materials and the designability of laminates, the concept of bidirectional energy absorption is proposed, which can absorb impact energy in both the transverse and vertical dimensions, and has a wider range of applications.

[0184] (2) A design method for the energy absorption performance of the corrugated structure is proposed;

[0185] This patent invention discloses a designable, easily formable corrugated sandwich bidirectional energy-absorbing structure with the following characteristics:

[0186] (1) The pleated core is a periodic corrugated single-curved panel with folded ends for bonding with the panel during assembly. Each single-curved panel has the same shape and can be repeatedly mass-produced. It is connected by adhesive to form a box structure, which is simple to assemble and low in cost.

[0187] (2) Make full use of the structure’s compressive deformation capacity under external load. The core plate with a single curved surface can be designed by designing the curved surface shape (fold height A and fold width L) and layup, and combined with the stiffness calculation method below, to obtain the transverse and longitudinal compressive fracture strength, and realize the bidirectional energy absorption function design.

[0188] (3) Core board manufacturing is based on corrugated positive mold laying and curing molding. The laminate board molding process is mature, the quality is stable, and it is easy to achieve the energy absorption design goal.

[0189] (4) This type of corrugated pleated unit is a multi-layer stacked structure. After being subjected to load, it loses energy through gradual pressure loss. The failure is a gradual folding, without sudden collapse. After failure, it still retains some load-bearing capacity.

[0190] Specifically, in one embodiment of this application, a corrugated sandwich design method includes the following steps:

[0191] Stress-strain calculation method for folded composite unidirectional plates:

[0192] For a certain angle on the wavy shape The stress-strain relationship at the point is:

[0193] (1)

[0194]

[0195] In the formula,

[0196]

[0197]

[0198] in:

[0199] This is the strain-displacement matrix;

[0200] Displacement in the X-axis direction;

[0201] Displacement in the Y-axis direction;

[0202] Displacement in the Z-axis direction;

[0203] Displacement in the YZ plane direction;

[0204] Displacement in the XZ plane direction;

[0205] Displacement in the XY plane;

[0206] The stress matrix;

[0207] Normal stress in the X-axis direction;

[0208] Normal stress in the Y-axis direction;

[0209] Normal stress in the Z-axis direction;

[0210] The shear stress is in the YZ plane direction;

[0211] The shear stress is in the XZ plane direction;

[0212] The shear stress is in the XY plane.

[0213] Reuter's Matrix for classical laminated plate theory is used to handle the multiple relationship between engineering shear strain and tensor shear strain:

[0214]

[0215] The angle transformation matrix is ​​determined based on the ripple shape:

[0216]

[0217] In the formula:

[0218]

[0219]

[0220] Here is the compliance matrix based on orthotropic materials:

[0221]

[0222] The softness matrix Converted into an expression of engineering elastic constants, thus obtaining Value:

[0223]

[0224] in:

[0225] like Figure 3 , , , Let be the elastic modulus of the material in directions 1, 2, and 3, where:

[0226] 1. The direction is the fiber direction of the core board, the axial length extension direction;

[0227] 2. Fibers perpendicular to the core board in the transverse width extension direction;

[0228] 3. The direction is perpendicular to the plane of the unidirectional core board, and the normal direction of the fiber lay-up plane;

[0229] For stress in When acting in a direction direction and The negative value of the ratio of strain in the direction, Values ​​are 1, 2, and 3;

[0230] For the shear modulus of the 2-3, 3-1, 1-2 plane;

[0231] Solving the above equations simultaneously yields formula (2):

[0232]

[0233] Formula (3):

[0234]

[0235] Formula (4):

[0236]

[0237] The parameters in the formula are calculated as follows:

[0238]

[0239]

[0240]

[0241]

[0242] By treating the sandwich structure as an array of individual cells and each bonded part as a symmetrical constraint boundary, the deformation under load can be calculated based on the above method, and the energy absorption displacement can be determined in combination with the material strength.

[0243] Total energy absorption is the primary indicator in the design process of a buffer structure; this sandwich structure absorbs energy throughout the entire compression deformation process. for:

[0244]

[0245] in The deformation displacement (m) of the sandwich structure;

[0246] The compressive displacement of the sandwich structure is Instantaneous load (N) at time;

[0247] Assuming the energy is constant during the energy absorption deformation process, i.e., F and Decoupling, i.e., F and It's irrelevant, I don't follow. change.

[0248] for Figure 1 The corrugated bidirectional energy-absorbing structure shown comprises m bonded corrugated composite panels. Each corrugated composite panel has a thickness of t and a length of l, containing n corrugations. Therefore, the deformation of each corrugated composite panel under a force F can be calculated as follows:

[0249]

[0250] In the formula, The equivalent modulus representing the direction of calculation can be calculated using formulas (2)-(4).

[0251] Taking an energy-absorbing structure with laminate thickness t=2mm, n=10, m=20, l=100mm as an example, the entire structure is subjected to... When subjected to an impact with an energy of 1000J (approximately equal to the impact force of a 10kg object falling from a height of 10 meters), the following are a set of calculation results: Parameter Ex (MPa) Ez (MPa) Energy Absorption Displacement in X Direction (mm) Energy Absorption Displacement in Z Direction (mm) Height A = 1 mm, Span L = 6 mm 17578 10409 0.38 0.49 Height A = 3 mm, Span L = 6 mm 10786 19126 0.48 0.36 Height A = 6 mm, Span L = 6 mm 9797 31647 0.51 0.28 Height A = 6 mm, Span L = 3 mm 9380 49645 0.52 0.22

[0252] In summary, this invention aims to solve the problems of insufficient energy absorption, poor structural stability, and uncontrollable failure modes in traditional sandwich structures under bidirectional impact. By introducing S-shaped wall panels with controllable buckling, segmented collapse mechanisms, and multi-scale energy dissipation paths, the invention achieves synergistic energy absorption, stable collapse, and high specific energy absorption in the compression and shear directions, thereby significantly improving the impact resistance and reliability of lightweight protective structures under complex loads.

[0253] This application provides a corrugated sandwich bidirectional energy-absorbing structure and design method, including a sandwich body composed of units made of periodically corrugated curved walls and upper and lower panels; the corrugated wall panels achieve controllable buckling and multi-stage collapse during loading through preset curvature, nodal transition structure and wall thickness distribution; the units form independent but mutually coupled energy dissipation paths along two main directions, enabling the structure to maintain a stable energy absorption mode under compression, shear and combined impact conditions; the structure incorporates a partition triggering mechanism, local plastic hinge control and shape constraint effect in its design, which significantly improves specific energy absorption, plateau stress stability and structural failure resistance, and can be widely used in scenarios such as traffic equipment collision protection, aerospace protection, electromechanical equipment buffering and building disaster reduction, achieving a balance between lightweight and high-efficiency energy absorption.

[0254] 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 substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A corrugated sandwich design method, characterized in that, Includes the following steps: The core board is a continuous single-curvature corrugated composite material board, and the equivalent mechanical parameters are calculated and designed through periodic sandwich units; Establish material compliance matrix, angle transformation matrix, and equivalent modulus calculation model to obtain the equivalent modulus of the sandwich structure in at least two orthogonal directions. The equivalent modulus obtained Determine the energy absorption deformation in the corresponding direction so that the sandwich structure meets the energy absorption target when subjected to external loads; Constructing an energy absorption model Based on the number of core boards m, the number of corrugations n, the thickness t of the core boards, and the equivalent modulus. Calculate the deformation of the target under absorbed energy. Used to determine the target energy-absorbing displacement of the sandwich structure, where The formula is as follows: The sandwich structure includes The core board is bonded together with blocks, and the thickness of a single core board is [missing information]. , length is Include ripples; The total energy absorbed during compression deformation: in, This serves as a buffer for the deformation displacement of the sandwich structure. The compressive displacement of the sandwich structure is Instantaneous load at that time.

2. The corrugated sandwich design method as described in claim 1, characterized in that, equivalent modulus Includes three directions, : The intermediate parameters in the formula are as follows: Here is the compliance matrix based on orthotropic materials: The softness matrix Converted into an expression of engineering elastic constants, thus obtaining Value: in: , , Let be the elastic modulus of the material in directions 1, 2, and 3; 1. The direction is the fiber direction of the core board, the axial length extension direction; 2. Fibers perpendicular to the core board in the transverse width extension direction; 3. The direction is perpendicular to the plane of the unidirectional core board, and the normal direction of the fiber lay-up plane; For stress in When acting in a direction direction and The negative value of the ratio of strain in the direction, Values ​​are 1, 2, and 3; For the shear modulus of the 2-3, 3-1, 1-2 plane; The angle of the wavy shape is The stress-strain relationship at the point is as follows: in: This is the strain-displacement matrix; Displacement in the X-axis direction; Displacement in the Y-axis direction; Displacement in the Z-axis direction; Displacement in the YZ plane direction; Displacement in the XZ plane direction; Displacement in the XY plane; The stress matrix; Normal stress in the X-axis direction; Normal stress in the Y-axis direction; Normal stress in the Z-axis direction; The shear stress is in the YZ plane direction; The shear stress is in the XZ plane direction; The shear stress is in the XY plane. To handle the multiple relationship between engineering shear strain and tensor shear strain: The angle transformation matrix is ​​determined based on the ripple shape: In the formula: The sandwich structure is regarded as an array structure of individual cells, and each bonding part is regarded as a symmetrical constraint boundary. The deformation after loading is calculated, and the energy absorption displacement is determined in combination with the material strength. Assuming the energy is constant during the energy absorption deformation process, i.e., F and Decoupling, F and It's irrelevant, I don't follow. change.

3. The corrugated sandwich design method as described in claim 1, characterized in that, The parameters of the curved surface configuration include at least the fold height A and the fold span L, and are adjusted accordingly. The ratio allows the energy absorption performance of the sandwich structure to be adjusted in both the lateral and vertical directions, enabling the sandwich structure to match the impact conditions of the target scenario. The balance parameters between peak energy absorption, specific energy absorption, and structural weight include: number of stacked layers, core plate thickness, and number of corrugations.

4. The corrugated sandwich design method as described in claim 1, characterized in that, By adjusting the number of corrugations n and the number of unit stacks m, the distribution of peak energy absorption and specific energy absorption in different directions is controlled, so that the residual load-bearing capacity of the sandwich structure after impact resistance meets the design target.

5. The corrugated sandwich design method as described in claim 1, characterized in that, The surface geometry design parameters of the core board are defined as follows: fold height A and fold span L, and absorption capacity distribution ratio. .

6. The corrugated sandwich design method as described in claim 1, characterized in that, The sandwich structure consists of at least three core plates of the same shape connected to form a box-type cell array. The connection method can be adhesive bonding, mechanical connection, or a combination thereof, to ensure the repeatability of the manufacturing process and the convenience of modular assembly.

7. The corrugated sandwich design method as described in claim 1, characterized in that, The core board is obtained through a positive mold laying and curing process. The geometric design parameters are defined, including the design of the layup angle, layup sequence and layup symmetry.

8. The corrugated sandwich design method as described in claim 1, characterized in that, The core board is a periodically corrugated single-curved panel with folded ends for bonding and adhering to the panel during assembly; The core board includes curved surfaces and layups; the core board is manufactured based on corrugated male mold layup and curing. The corrugated pleated unit of the sandwich structure is formed by stacking three or more layers of core board.

9. A corrugated sandwich bidirectional energy-absorbing structure, employing the corrugated sandwich design method according to any one of claims 1-8, characterized in that, It includes a periodically arranged core plate, which is a regular cell array; the core plate is provided with a pleated configuration with a continuous curvature distribution; The core board adopts a laminated structure, consisting of at least three reinforcing layers with preset layup angles; The core board has a flanged end for bonding with the panel.

10. A corrugated sandwich bidirectional energy-absorbing structure as described in claim 9, characterized in that, The core board forms a box-type array structure through adhesive bonding, interlocking or mechanical connection, so that each unit cell can maintain coordinated deformation after being loaded; The core board comprises at least three stacked core material units, exhibits a progressive folding pattern when compressed, and retains residual load-bearing capacity after being crushed. The S-curve surface of the core board is equipped with a surface with continuously varying curvature.

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