In-Plane Crushing of Square Honeycomb Cores, Part I: Mechanical Behaviors

2012 ◽  
Vol 170-173 ◽  
pp. 3220-3223 ◽  
Author(s):  
De Qiang Sun ◽  
Wen Ting Cao ◽  
Meng Cai
Keyword(s):  
Finite Element ◽  
Impact Velocity ◽  
Inertia Effect ◽  
Mechanical Behaviors ◽  
Empirical Formulas ◽  
Plateau Stress ◽  
Honeycomb Cores ◽  
Dynamic Enhancement ◽  
Deformation Modes ◽  
Force Displacement

Mechanical behaviors of square honeycombs cores (SHCs) are investigated by using the finite element (FE) simulations under the in-plane dynamic crushing loadings. With the increasing impact velocities, different deformation modes are observed. The force-displacement curves include four regimes with distinct characteristics. The plateau stresses are calculated for the SHCs with different configuration parameters. The dynamic plateau stress is the sum of the static plateau stress and the dynamic enhancement due to the inertia effect. The static plateau stress is proportional to the relative density of SHCs. The dynamic enhancement stress is proportional to the square of impact velocity and the relation coefficient depends on the configuration parameters. The empirical formulas of dynamic plateau stress in terms of configuration parameters and impact velocity are given.

In-Plane Crushing of Triangular Honeycomb Cores, Part II: Under Dynamic Loadings

2012 ◽  
Vol 476-478 ◽  
pp. 2481-2484
Author(s):  
De Qiang Sun ◽  
Yan Feng Guo ◽  
Rong Hou Xia
Keyword(s):  
Finite Element ◽  
Kinetic Energy ◽  
Impact Velocity ◽  
Inertia Effect ◽  
Plateau Stress ◽  
Dynamic Behaviors ◽  
Dynamic Loadings ◽  
Honeycomb Cores ◽  
Dynamic Enhancement ◽  
Deformation Modes

The dynamic behaviors of triangular honeycombs cores (THCs) are investigated by using the finite element (FE) simulations under the in-plane dynamic crushing loadings. With the increasing impact velocities, different deformation modes are observed and the kinetic energy of specimen increases rapidly. The in-plane dynamic plateau stress is the sum of the static plateau stress and the dynamic enhancement due to the inertia effect. The static plateau stress has been discussed in Part I. When all configuration parameters are kept constant, the dynamic enhancement stress is proportional to the square of impact velocity. For a given impact velocity, the dynamic enhancement stress is proportional to the density of THCs when the expanding angle is kept constant. The in-plane dynamic plateau stress is expressed empirically in terms of configuration parameters and impact velocity.

In-Plane Crushing of Square Honeycomb Cores, Part II: Energy Absorption and Cushioning Optimization

2012 ◽  
Vol 170-173 ◽  
pp. 3237-3240
Author(s):  
De Qiang Sun ◽  
Zu Yong Jiang ◽  
Yan Bin Wei
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
Physical Analysis ◽  
Fe Model ◽  
Mechanical Parameters ◽  
Empirical Formulas ◽  
Plateau Stress ◽  
Optimal Energy ◽  
Honeycomb Cores ◽  
Dynamic Densification

The finite element (FE) model designed in Part I is used to obtain the cushioning mechanical parameters of square honeycomb cores (SHCs) under in-plane dynamic loadings. A simplified energy absorption model is proposed to evaluate the energy absorption performance of SHCs, which shows that the optimal energy absorption per unit volume is related to dynamic plateau stress and dynamic densification strain that are affected by configuration parameters and impact velocity. The optimal energy absorption efficiency is the reciprocal of dynamic densification strain. The dynamic plateau stress has been discussed in Part I. For SHCs, the dynamic densification strain is independent of impact velocity and determined by configuration parameters. The empirical formulas of cushioning mechanical parameters are derived from physical analysis of FE results. Based on these empirical formulas, the practical cushioning optimization algorithm is presented.

In-Plane Quasi-Static Crushing of Cissoidal Hexagonal Honeycomb Cores

2012 ◽  
Vol 446-449 ◽  
pp. 3736-3739 ◽  
Author(s):  
De Qiang Sun ◽  
Miao Liu ◽  
Ying Xue Zhu
Keyword(s):  
Fe Simulation ◽  
Edge Length ◽  
Mechanical Behaviors ◽  
Response Curves ◽  
Plateau Stress ◽  
Deformation Processes ◽  
Simulation Results ◽  
Data Tables ◽  
Honeycomb Cores ◽  
Force Displacement

The mechanical behaviors of cissoidal hexagonal cores (CHCs) are investigated by using the finite element (FE) simulations under the in-plane quasi-static crushing loadings. The calculated deformation processes, response curves and values of plateau stress are presented in the forms of diagrams, force-displacement curves or data tables, respectively. The influences of ratio of cell wall thickness to edge length and expanding angle on the quasi-static plateau stress are discussed in detail. The empirical expressions of quasi-static plateau stress in terms of configuration parameters are given based on the FE simulation results.

In-Plane Crushing of Triangular Honeycomb Cores, Part I: Under Quasi-Static Loadings

2012 ◽  
Vol 476-478 ◽  
pp. 2501-2504
Author(s):  
De Qiang Sun ◽  
Yan Feng Guo ◽  
Guo Tu Xu
Keyword(s):  
Cell Wall ◽  
Wall Thickness ◽  
Deformation Mode ◽  
Edge Length ◽  
Cell Wall Thickness ◽  
Response Curves ◽  
Plateau Stress ◽  
Honeycomb Cores ◽  
Force Displacement ◽  
Scale Coefficient

Mechanical behaviors of triangular honeycombs cores (THCs) are investigated by using the finite element (FE) simulations under the in-plane quasi-static crushing loadings. The deformation process is described in the form of response curves and deformation mode diagrams. The force-displacement curves include four deformation regimes with distinct characteristics. The quasi-static plateau stresses are calculated for the THCs with different configuration parameters. The influences of ratio of cell wall thickness to edge length and expanding angle on the quasi-static plateau stress are discussed in detail. The quasi-static plateau stress is proportional to the relative density of THCs and the expanding angle determines the scale coefficient. The empirical formula of quasi-static plateau stress in terms of ratio of cell wall thickness to edge length and expanding angle is given based on the FE simulation results.

Effect of Random Defects on Dynamic Response of Honeycomb Structures

2012 ◽  
Vol 706-709 ◽  
pp. 805-810 ◽  
Author(s):  
Zhi Jun Zheng ◽  
Ji Lin Yu
Keyword(s):  
Impact Velocity ◽  
Cell Walls ◽  
Plateau Stress ◽  
Impact Surface ◽  
Critical Impact Velocity ◽  
Crushing Behavior ◽  
The Impact ◽  
Stress Uniformity ◽  
Random Defects ◽  
Deformation Modes

The dynamic crushing behavior of cellular metals is closely related to their microstructure. Two types of random defects by randomly thickening/removing cell walls are investigated in this paper. Their influences on the deformation modes and plateau stresses of honeycombs are studied by finite element simulation using ABAQUS/Explicit code. Three deformation modes, i.e. the Homogeneous Mode, the Transitional Mode and the Shock Mode, are used to distinguish the deformation patterns of honeycombs under different impact velocities. The critical impact velocity for mode transition between the Homogeneous and Transitional modes is quantitatively determined by evaluating a stress uniformity index, defined as the ratio between the plateau stresses on the support and impact surfaces. It is found that the critical impact velocity decreases with increasing thickening ratio but increases with increasing removing ratio. The plateau stress on the impact surface heavily depends on the impact velocity due to the inertia effect. The random defects lead to a weakening effect on the plateau stress. For the honeycombs with randomly removing cell walls, the weakening effect is especially obvious at a moderate impact velocity. For the honeycombs with randomly thickening cell walls, the weakening effect is particularly severe at a low impact velocity, but this effect almost disappears when the impact velocity is high enough.

Dynamic Crushing of Hexagonal Honeycombs under In-Plane Loading

2011 ◽  
Vol 79 ◽  
pp. 83-86
Author(s):  
Xin Chun Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Energy Absorption ◽  
Impact Velocity ◽  
Edge Length ◽  
Cellular Materials ◽  
Plateau Stress ◽  
Dynamic Finite Element ◽  
Explicit Dynamic ◽  
Dynamic Crushing

The in-plane dynamic crushing of hexagonal honeycombs was numerically studied by means of explicit dynamic finite element method using ANSYS/LS-DYNA. Under the assumption that the edge length and thickness were the same, the metal honeycomb models filled with convex and concave cells were established. And then the effects of expanding angle and impact velocity on the plateau stress and the energy absorption capacities of hexagonal honeycombs were discussed in detail. Numerical results show that the energy absorption capacities of convex hexagonal honeycombs are stronger than the concave ones. These results will provide some useful guides for the dynamic energy absorption design of cellular materials.

In-Plane Cushioning Optimization of Multilayer Regular Triangular Honeycombs

2012 ◽  
Vol 510 ◽  
pp. 147-153
Author(s):  
De Qiang Sun ◽  
Meng Cai ◽  
Wen Ting Cao
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
Element Model ◽  
High Impact ◽  
Physical Analysis ◽  
Empirical Formulas ◽  
Plateau Stress ◽  
Representative Cell ◽  
Absorption Performance ◽  
Dynamic Densification

A finite element model is designed to obtain the mechanical parameters about cushioning property of multilayer regular triangular honeycombs under the in-plane crushing loadings with high impact velocities. A simplified energy absorption model is put forward to evaluate the energy absorption performance, which shows that the optimal energy absorption per unit volume is related to dynamic plateau stress and dynamic densification strain. Both depend on the configuration parameters of representative cell and impact velocity. From the physical analysis and discussion of the numerical results, the empirical formulas of dynamic densification strain and dynamic plateau stress are suggested in terms of configuration parameters and impact velocity. Based on these empirical formulas, a feasible cushioning optimization algorithm is put forward and presented.

Dynamic Behavior of Cellular Materials under Combined Shear-Compression

2016 ◽  
Vol 835 ◽  
pp. 649-653
Author(s):  
Yuan Yuan Ding ◽  
Shi Long Wang ◽  
Zhi Jun Zheng ◽  
Li Ming Yang ◽  
Ji Lin Yu
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Finite Element Model ◽  
Nonlinear Regression ◽  
Element Model ◽  
Cellular Materials ◽  
Regression Method ◽  
Plateau Stress ◽  
Nonlinear Regression Method ◽  
Biaxial Behavior

A 3D cell-based finite element model is employed to investigate the dynamic biaxial behavior of cellular materials under combined shear-compression. The biaxial behavior is characterized by the normal stress and shear stress, which could be determined directly from the finite element results. A crush plateau stress is introduced to illustrate the critical crush stress, and the result shows that the normal plateau stress declines with the increase of the shear plateau stress, which climbs with the increase of loading angle. An elliptical criterion of normal plateau stress vs. shear plateau stress is obtained by the nonlinear regression method.

scholarly journals Young’s Modulus of Polycrystalline Titania Microspheres Determined by In Situ Nanoindentation and Finite Element Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Peida Hao ◽  
Yanping Liu ◽  
Yuanming Du ◽  
Yuefei Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Deformation Mechanisms ◽  
Displacement Curve ◽  
Element Simulation ◽  
Nanoindentation Experiment ◽  
Force Displacement

In situ nanoindentation was employed to probe the mechanical properties of individual polycrystalline titania (TiO2) microspheres. The force-displacement curves captured by a hybrid scanning electron microscope/scanning probe microscope (SEM/SPM) system were analyzed based on Hertz’s theory of contact mechanics. However, the deformation mechanisms of the nano/microspheres in the nanoindentation tests are not very clear. Finite element simulation was employed to investigate the deformation of spheres at the nanoscale under the pressure of an AFM tip. Then a revised method for the calculation of Young’s modulus of the microspheres was presented based on the deformation mechanisms of the spheres and Hertz’s theory. Meanwhile, a new force-displacement curve was reproduced by finite element simulation with the new calculation, and it was compared with the curve obtained by the nanoindentation experiment. The results of the comparison show that utilization of this revised model produces more accurate results. The calculated results showed that Young’s modulus of a polycrystalline TiO2microsphere was approximately 30% larger than that of the bulk counterpart.

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