Beetle Elytron Plates Research Articles

Elastic local buckling behaviour of beetle elytron plate

Beetle elytron plate (BEP) is a biomimetic sandwich structure inspired by the internal architecture of beetle elytra and characterisedby trabeculae in the core. This type of structure has been shown to possess superior mechanical properties to conventional sandwich plates; however, there are no studies that evaluate its structural bending resistance. This paper develops an analytical method to calculate the key component of bending resistance of BEPs: the elastic local buckling load of the compression skin. It assumes that the compression skin of BEPs is simply supported by the trabecular core. After eliminating local buckling in the edges of the compression skin outside the trabeculae, two buckling zones, depending on the ratio (η) of trabecular radius to the distance between two adjacent trabeculae, are identified. At low η values (η≤0.25), elastic buckling occurs in the space of the compression skin surrounded by four adjacent trabeculae. Beyond the critical value of η (η>0.25), buckling occurs in the compression skin enclosed by individual trabecula. Guided by finite element simulation results, this paper identifies a new suite of deformation shape functions and derives local elastic buckling load for the compression skin according to the principle of minimal total potential energy. Afterwards, a convenient quadratic polynomial regression equation is proposed to modify the elastic buckling coefficient of the compression skin of equivalent conventional grid honeycomb sandwich plates, with the maximum difference between analytical calculation results and finite element simulation results being about 7%.

Heat transfer characteristics of straw-core paper honeycomb plates (beetle elytron plates) I: Experimental study on horizontal placement with hot-above and cold-below conditions

Abstract To develop functional sandwich plates (FHPs) and identify new ways to use straw, straw-core paper honeycomb plates (SHPs) were prepared. The mechanisms of the influence of the spatial distribution of various filling systems on the heat transfer performance of SHPs were investigated, and the following results were obtained. 1) The equivalent thermal conductivity (λE) of the three FHPs were significantly lower than that of the honeycomb plate (HP), and the λE of all the FHPs met or approached the requirements of high-efficiency heat insulation materials for envelope structures. Moreover, the λE values of the three FHPs were closest to each other at the upper and lower limits of the tested thickness. 2) The spatial distribution characteristics of the spherical particle and slender filling systems under natural filling conditions, their corresponding simple heat transfer models and the concept of divisional local radiative (DLR) heat transfer were presented for the first time. 3) The fundamental factor determining the magnitudes of the λE of the HP and FHPs was the presence of DLR in the core layer structures, and the heat transfer characteristics of the FHPs were the result of the combined actions of the DLR and filling material properties.

Analysis of the convective heat transfer and equivalent thermal conductivity of functional paper honeycomb wall plates

ABSTRACT For the development of functional honeycomb plates (FHPs) and efficient resource utilization of straw, based on the measurement of the equivalent thermal conductivity (λE) of paper honeycomb plates (HPs) and FHPs, including straw-core paper honeycomb plates (SHPs), under cold-left and hot-right conditions, the influence mechanism of the system geometry parameters on the convective heat transfer of HPs and the heat insulation performance of FHPs by fillers are discussed. The results are as follows. 1) Compared with the case of hot-above and cold-below conditions, the convective heat transfer ratio of HP increases substantially under cold-left and hot-right conditions. 2) The main heat transfer modes of the FHPs are radiative heat transfer between the wall (including the panel and side) and filling material and solid heat conduction in the filling material, supplemented by a small amount of heat conduction through air or local convection heat transfer in the void. 3) The higher the temperature is, the greater the FHP equivalent thermal conductivity, with little influence from the heat transfer direction. 4) It is relatively conservative to use the heat transfer effect of HPs and FHPs to evaluate that of beetle elytron plates (BEPs) and functional beetle elytron plates (FBEPs). This study lays a foundation for the application of multifunctional BEPs and HPs in building envelopes.

Relation between the geometric parameters and the composite heat transfer of paper honeycomb plates under cold-above/hot-below conditions and the corresponding influence mechanism

To develop functional honeycomb plates (HPs) with great thermal performance, This paper uses a heat flow meter to determine the equivalent thermal conductivity λ E of honeycomb plates (HPs) positioned horizontally under cold-above/hot-below conditions and combined with theoretical calculations, the influence mechanism of their geometric parameters on their heat transfer performance were investigated with different thicknesses h and cell wall lengths of 8 mm and 16 mm (HP8 and HP16, respectively). The results show that the thermal insulation performance of HPs with different cell side lengths varies with the plate thickness. HP8 presented a better thermal insulation performance when h = 40–60 mm. Based on this, the concepts of matching honeycomb structure and matching convection and the suggestions that according to the needs of a project, HP8 or HP16 can be reasonably selected, and the stacking of two kinds of plates can be optimized were first proposed. And it can be obtained that if the experimental λ E results of a HP are applied to a beetle elytron plate with the same thickness and honeycomb structure size, the heat insulation of the beetle elytron plate (BEP) would be superior to that of the HP. This paper lays a theoretical foundation for the research and development of multifunctional BEPs with heat insulation properties was verified. Finally, the internal influence mechanism of the difference in temperature distribution on the upper and lower surfaces and the three-dimensional size of the honeycomb cells on the matching honeycomb structure and matching convection. • HP 8 is a matching honeycomb structure when h = 10–20 mm, so its convection is stronger than HP 16 . • The increase in the convection of HP 16 was significantly faster than that of HP 8 and the radiation of two plates. • The conclusions can be applied to the multifunctional biomimetic beetle plate. • Four inferences point out the direction for further research in this field.

The compressive property of a fiber‐reinforced resin beetle elytron plate and its influence mechanism

AbstractTo develop composite material beetle elytron plates (BEPs), short basalt fiber‐reinforced epoxy resin BEPs with hollow trabeculae and honeycomb walls were fabricated exploratively. Through comparison with honeycomb plates (HPs) with the same wall thickness, the basic mechanical performance, failure mode and influence mechanism were studied via out‐of‐plane compression tests. The results show that compared with HPs, the specific strength and energy consumption per volume of BEPs can be at least 18% and 112% higher, respectively; however, the increase is less than half that of BEPs made of ductile materials. The former is due to the synergistic mechanism of the trabecular‐honeycomb structure in the BEP core layer, which endows the composite BEPs with better ductility than HPs, while the latter is caused by the prominent brittleness of the composite material used in this study. Additionally, the height‐to‐thickness ratio of the plate honeycomb wall in this article is not large enough. Thus, the core has great rigidity and fails to buckle in experiments; instead, shear failure of the core material occurs. This study reveals for the first time the mechanical compression properties and failure mechanism of brittle material BEPs and shows a direction for developing BEPs in similar material types.

A new type of bionic grid plate—The compressive deformation and mechanical properties of the grid beetle elytron plate

To develop lightweight and biomimetic structural materials, in this paper, the compressive deformation and mechanical properties of the grid beetle elytron plate (GBEP) with the same core volume as the end-trabecular beetle elytron plate (EBEP) under compression were investigated for the first time. (1) The B-type deformation mode of trabeculae is clarified, which is a higher stage of independent deformation than the Φ-type deformation mode in the beetle elytron plate (BEP). Additionally, the four deformation modes of the BEP are divided into three stages in succession from easy to difficult: C-type, Φ-type and S (B)-type deformation. This paper verifies that the compressive strength and energy absorption capacity of the GBEP increase by 35% and 87%, respectively, relative to those of the grid plate (GP) with the same volume. (2) Although the number of trabeculae of the GBEP is significantly less than that of the EBEP, each trabecula in the GBEP has one more honeycomb wall constraint than each trabecula in the EBEP. The increase range of the compressive properties of the GBEP relative to the GP is greater than that of the EBEP relative to the honeycomb plate (HP). This confirms the prediction that the compressive properties can be effectively improved by appropriately increasing the constraints on the trabeculae. This paper deepens and enriches the knowledge regarding the biomimetic application system of BEPs, lays the foundation for GBEPs, whose preparation is convenient, and accelerates the applications of GBEPs.

Influence Mechanism of the Trabecular and Chamfer Radii on the Three-point Bending Properties of Trabecular Beetle Elytron Plates

To improve the mechanical properties of Trabecular Beetle Elytron Plates (TBEPs, a type of biomimetic sandwich structure inspired by the beetle elytron) under transverse loads, three-point bending tests are performed to investigate the influence of the trabecular and chamfer radii of the core structure on the mechanical performance of TBEPs manufactured by 3D printing technology. The results show that the three-point bending performance of TBEPs can be improved by setting reasonable trabecular and chamfer radii; however, excessive increases in these radii can cause a decline in the mechanical performance. For the reason, these two structural parameters can enhance the deformation stiffness of the whole structure and the connection property between the core and skin, which is also the mechanical reason why Prosopocoilus inclinatus beetle elytra have thick, short trabeculae with a large chamfer radius. However, when these radii increase to a certain extent, the cracks are ultimately controlled between two adjacent trabeculae, and the failure of the plate is determined by the skin rather than the core structure. Therefore, this study suggests a reasonable range for trabecular and chamfer radii, and indicates that TBEPs are better suited for engineering applications that have high compression requirements and general bending requirements.

Influence of the Chamfer on the Flexural Properties of Beetle Elytron Plates

To improve the flexural properties of Beetle Elytron Plates (BEPs) and clarify the effect of the transition arcs (chamfers) between the skins and the trabeculae, the chamfers were set in BEPs, and then the influence of the chamfer on BEPs??? mechanical properties was investigated via experimentation and the Finite Element Method simulation (FEM). The results indicate that the influence of the chamfer on the flexural properties and ductility was most obvious in the Trabecular Beetle Elytron Plates (TBEPs), less obvious in the Honeycomb Plates (HPs) and basically no effect was observed on End-trabecular Beetle Elytron Plates (EBEPs). The chamfer can improve the mechanical stability of EBEPs. As the chamfer diameter increased in the BEPs, the length of the residual trabecular root on the skin increased when failure occurred in the TBEPs. The crack position in the honeycomb walls of the HPs gradually shifted from the skin to the center. The EBEPs continued to exhibit oblique cracks. From the perspective of the force characteristics of these BEPs, combined with numerical simulation, the influence mechanism of the chamfer on their flexural properties was investigated.

Optimization of the Structural Parameters of the Vertical Trabeculae Beetle Elytron Plate Based on the Mechanical and Thermal Insulation Properties

According to the excellent structure of the beetle elytron plate (BEP), a new type of bionic prefabricated wallboard with vertical trabeculae and honeycomb walls (the vertical trabeculae beetle elytron plate: VBEPsc) was proposed. The relationships between the main structural parameters, including the concrete frame thickness (T), honeycomb wall thickness (t), trabecula number (N) and trabecular radius (R), and the performance of the VBEPsc were analyzed. In addition, to improve the mechanical and insulation performance of the VBEPsc, an initial optimal design was determined. The results showed that 1) in addition to the mechanical properties of the VBEPsc being mainly affected by T, as is known, N had an apparent impact on the stiffness of the VBEPsc; the insulation performance was affected greatly by T, N, and t. 2) Under the given conditions, the mechanical properties of the optimized VBEPsc met the requirements for bearing capacities and serviceability; The insulation performance of the optimized VBEPsc met the requirements for self-insulating walls of category II buildings in areas that are cold in winter and hot in summer. In addition, a double-layer mold and complete production technology for VBEPsc were proposed. These works started a discussion for the application of such prefabricated wallboards.

Vibration properties and transverse shear characteristics of multibody molded beetle elytron plates

This study utilized cantilever experiments to investigate the vibration properties of multibody molded beetle elytron plates (BEPs), which is a type of biomimetic sandwich plate inspired by beetle elytra; the corresponding shear characteristics were further revealed by a finite element method (FEM). The following results were obtained: (1) Experimental results suggest that the maximum displacement response of the BEPs was about 25% less than that of a honeycomb plate with almost the same first natural frequency, which indicates that a BEP with reasonable structural parameters has the potential to replace a honeycomb plate to achieve better vibration performance; (2) The trabecular structure not only enhanced the shear stiffness of the core layer in column areas but also the skins in the honeycomb wall areas, thus changing the distribution of the shear force in the different components and improving the mechanical performances of the BEP; and (3) Although this enhancement effect from trabeculae was not uniform, the average shear force proportion of the skins (or core structure) in the entire BEP structure was very close to that of the honeycomb plate. Therefore, the shear calculation assumption used for honeycomb plates is still applicable in the BEP. The results provide an experimental basis for the design and application of BEPs and inspiration for the development of related products in vibrational environments.

Characteristics of compressive mechanical properties and strengthening mechanism of 3D-printed grid beetle elytron plates

The mechanical properties and the influence mechanism of grid beetle elytron plates (GBEPn), which were fabricated from an ABS resin material using 3D printing technology, under compression were investigated. Different values of ηc, i.e., ratio of r (centerline radius of the cylinder) to L (length of the basic element), were considered for given yield stress coefficients and matching coefficient. The results revealed that the compressive strength of the GBEPn was comparable to that of the end-trabecular beetle elytron plate (EBEP), whereas the energy absorption capacity of the GBEPn was higher than that of the EBEP. When the ηc was increased, the mechanical properties of the GBEPn exhibited CEEP (compressive strength—elastic stage and energy absorption capacity—plastic stage) characteristics. The basis for the CEEP characteristics and the internal strengthening mechanism were explored. The synergistic effect of the trabeculae and the walls and, hence, the mechanical properties improved with increasing yield stress. The results of the present study will accelerate the application of beetle elytron plates.

The flexural property and its synergistic mechanism of multibody molded beetle elytron plates

To improve the applications of beetle elytron plates (BEPs, which are biomimetic sandwich plates inspired by beetle elytra), the flexural performance and its synergistic mechanism of multibody molded BEPs were investigated via cantilever testing and finite element method (FEM). The results are summarized as follows. (1) Although debonding damage causes failure of the multibody molded BEPs and honeycomb plate and the reasonable range of trabecular size for BEPs is narrow, both the optimal loading capacity per mass and failure deformation of the BEPs are over two times those of the honeycomb plate. (2) A flexural synergistic mechanism is revealed in the trabecular-honeycomb core structure of BEPs; this mechanism causes the maximum deformation of core structure to gradually transfer from the honeycomb wall to the trabeculae with the increase in η (the ratio of the trabecular radius to the distance between the center points of two trabeculae), which means the different stretching behaviors in these core structures. (3) Unlike the compressive mechanism of BEPs, by controlling and balancing the deformation degrees of the trabeculae and honeycomb walls, the flexural mechanism achieves a minimum core deformation and an optimal flexural performance. These results suggest a qualitative relationship between the deformation behavior of trabecular-honeycomb core structure and bending performance of the whole BEP, and provide a solid foundation for subsequent research and the considerable application potential of this biomimetic sandwich structure in many fields.

Experimental verification and optimization research on the energy absorption abilities of beetle elytron plate crash boxes

To develop a new type of biomimetic sandwich plate crash box inspired by beetle elytra (referred to as the beetle elytron plate (BEP) crash box) with a better energy absorption capability, we conducted experimental verification and optimization research on two methods proposed in our previous studies: changing the amplitude (A) of the deformation leading line predicted by the finite element method and setting the trabeculae in the middle of the honeycomb walls. The following results were determined. (1) The method of increasing A to reduce the peak force of the BEP crash box is effective, whereas the latter method is invalid. (2) The latter method is invalid because the unit structure (the BEP crash box) is different from the multivariate structure (the BEP) used to determine the prediction due to the change of constraint condition on the trabeculae provided by the honeycomb walls. (3) An optimum A of 1.0 is proposed for BEP crash boxes with better energy absorption abilities and more stable successively laminated deformation. Specifically, the main peak force of the BEP crash box is approximately the same as that of the conventional one, while the structural energy absorption (SEA) and load uniformity (LU) of BEP crash boxes are at least 3 times and between only one-third and one-fourth those of conventional crash box, respectively, meaning that BEP crash boxes can be directly used to replace conventional one and to significantly improve security. Thus, these results provide an experimental basis for further research on BEP crash boxes.

The flexural properties of end-trabecular beetle elytron plates and their flexural failure mechanism

In pursuit of the development of lightweight biomimetic functional–structural materials, this study investigated the flexural properties and failure characteristics of end-trabecular beetle elytron plates (EBEPs) as well as the flexural mechanism and the role of the trabeculae. The results were as follows: (1) The EBEP specimens showed better ductility performance after the peak load was reached, and their specific elastic strength and specific flexural strength were similar to those of honeycomb plates (HPs). In an EBEP before failure, the lower skin in the same location as the load was significantly stretched, and the trabeculae in the core showed two failure modes: destruction by means of slant cracks and vertical cracks. (2) The failure mechanism of the trabeculae in an EBEP was investigated by qualitatively analyzing the load and deformation of the parts adjacent and nonadjacent to the loading point. From the macro point of view, the cores of EBEP and HP are continuous. These cores can not only bear tension with lower skins, but also divide upper skins into much smaller parts and play a role as reinforcing ribs. The equivalent trabeculae in EBEP are closed ended, the honeycomb walls are narrow, and these two parts can support and constrain each other.

Beetle elytron plate and the synergistic mechanism of a trabecular-honeycomb core structure

For the development of lightweight biomimetic materials, the compressive properties of the beetle elytron plate (BEP, a type of biomimetic sandwich plate inspired from beetle elytra) and the underlying mechanism thereof were investigated. With the following results: (1) The shared mechanism of trabeculae was revealed by using structural analysis. It is further predicted that a BEP with hollow trabeculae should possess enhanced compressive properties. (2) When the trabecular number ( N ) in a hexagonal unit of the honeycomb is less than three, the compressive strength of the BEP is rapidly increased with the increment of N . When N is over four, the deformation capacity is significantly improved because of the arising of S-type buckling deformation in the core structure of the BEP. Furthermore, the definition of the BEP is proposed combined with the biological structure of the beetle elytra. (3) When N =6 and the external diameter of trabeculae is equal to the length of honeycomb walls, the synergistic mechanism between the trabeculae and the honeycomb walls in BEPs is fully exerted. Namely, the trabecula restricts the deformation of the honeycomb walls; in turn, the honeycomb walls provide lateral support for the trabecula. This mechanism leads the core in the BEP to generate an S-type global buckling deformation producing the best compressive properties. The results will greatly impact the biomimetic field of beetle elytra and many industries in which honeycomb structure also serves as a key component.

Effects of changes in the structural parameters of bionic straw sandwich concrete beetle elytron plates on their mechanical and thermal insulation properties

To develop new, environmentally friendly prefabricated building materials, the effects of individual changes in structural parameters on the mechanical and thermal insulation properties of straw sandwich concrete beetle elytron plates (SCBEPs), i.e., sandwich plates with trabeculae constituting the core layer structure, were analyzed by ABAQUS. In addition, based on the analysis results, the structural parameters were preliminarily optimized. The results revealed the following. 1) The bearing capacity of a SCBEP is mainly controlled by deformation (i.e., the maximum deflection). The two most influencing factors on the deflection are the panel thickness T and the trabecular radius R. In contrast, although the panel area is very large, the influence of changing the panel thickness on the thermal insulation performance ranks only third. This demonstrates that the thermal bridge effect of the concrete trabeculae and edges is the primary limitation on further improvements to the thermal insulation performance of SCBEPs. 2) Based on the effects of individual changes in structural parameters on the performance of SCBEPs and their actual processing and application requirements, the structural parameters of a SCBEP with optimized mechanical properties and thermal insulation properties are determined. 3) Compared with aerated concrete wallboards, the optimized SCBEP has a higher rigidity, more compacted surface and better durability. Compared with straw concrete wallboards, the optimized SCBEP has a higher straw content and better thermal insulation performance. Thus, it provides a new avenue for the development of a new, lightweight wallboard.

Experimental and numerical study on the energy absorption abilities of trabecular–honeycomb biomimetic structures inspired by beetle elytra

This study proposes a type of trabecular–honeycomb biomimetic structures with high-efficiency energy-absorbing abilities inspired by beetle elytra. Because the trabecular structure is distributed at the ends of the honeycomb walls, the proposed structure is named an end-trabecular beetle elytron plate crash box, or EBEP crash box for simplification. A comparison between the EBEP crash box and conventional crash box (a buffering structure generally used in modern devices and vehicles) is conducted using compression experiments and finite element method. We present the following results. (1) In contrast to the fluctuation stage with a low force in a conventional crash box, the force–displacement curve of the EBEP crash box possesses a rising stage and an approximate plateau with a higher force; as a result, the absorbing energy ability and compression force efficiency are 5 and 2.6 times greater than those of a conventional crash box, respectively. (2) Experimental and numerical comparisons reveal that there is cracking failure in the conventional crash box; however, the coordinated and uniform S-typed laminated compression deformation is developed in the EBEP crash box. (3) The influences of the amplitude (A) of the sine wave deformation line on the peak force and the compression force efficiency of the EBEP crash box are investigated, thereby providing a feasible method for adjusting the peak force according to different engineering requirements. These results provide new inspiration for applying EBEP crash boxes and exploiting new buffering structures and materials in the energy-absorbing field.

The compressive properties and strengthening mechanism of the middle-trabecular beetle elytron plate

For the development of new types of lightweight sandwich structures, the compressive properties and strengthening mechanism of the middle-trabecular beetle elytron plate were investigated for various values of η (the ratio of the trabecular radius to the honeycomb wall length). The results are as follows: (1) When η = 0.1, the increases in the compressive strength and standard energy absorption capacity of the middle-trabecular beetle elytron plate compared with the honeycomb plate exceed those of the end-trabecular beetle elytron plate; with an increase to η = 0.15, the compressive strength remains nearly the same, the energy absorption capacity undergoes a significant further increase, and the trabeculae exhibit Φ-type failure. (2) The strengthening mechanism that gives rise to the compressive properties of the middle-trabecular beetle elytron plate is proposed as follows: the trabeculae are located at the center of the honeycomb walls, where the maximum deformations would otherwise occur; they constrain the deformation of the honeycomb walls; and the number of trabeculae in the middle-trabecular beetle elytron plate also exceeds that in the end-trabecular beetle elytron plate. (3) Middle-trabecular beetle elytron plates have the advantage of facile manufacturing, which will establish a basis for promoting the application of beetle elytron plates.

Influence of honeycomb dimensions and forming methods on the compressive properties of beetle elytron plates

For developing lightweight and high-strength biomimetic sandwich structures, this study investigates the influence of honeycomb dimensions and forming methods on the mechanical properties of beetle elytron plates relative to honeycomb plates via compression experiments and the finite element method. The results indicate that the trabecular-honeycomb core structure in beetle elytron plates can increase the compressive strength by approximately 50% and double the energy absorption capacity of honeycomb plates with the same material costs. Furthermore, the influence of three types of forming methods on the compressive properties of beetle elytron plates is investigated by comparing the different deformation modes of these structures with those of honeycomb plates. Based on these findings, application recommendations regarding the forming methods of beetle elytron plates are presented to facilitate the structural design and preparation techniques according to the performance requirements of different fields, which will accelerate the industrial application of these biomimetic structures.

Compression properties of metal beetle elytron plates and the elementary unit of the trabecular-honeycomb core structure

This paper investigates the mechanical properties of metal beetle elytron plates (a type of biomimetic sandwich structure) and the elementary unit of the trabecular-honeycomb core structure by compression experiments. The following conclusions are drawn: (1) after reaching the compressive strength, the stress–strain curve of the beetle elytron plate contains a yield plateau that advantageously exploits the material strength of metal and its plastic deformation capacity; (2) the elementary unit of the core structure in beetle elytron plates is proposed explicitly based on the trabecular characteristic; and (3) this elementary unit remains relatively unchanged on the constraint condition of the trabecular structure and has high independence and stability when placed under out-of-plane compression. Thus, the yield plateau and variation tendency of the compressive strength after buckling of this elementary unit are highly consistent with that of the entire structure, which provides the basis for further research on the equivalent parameters and equivalent model of the beetle elytron plate and its trabecular-honeycomb core structure.