Crashing analysis and multiobjective optimization for thin-walled structures with functionally graded thickness

This paper treats the dynamic response and energy absorption of aluminum foamfilled
conical tubes under axial impact loading using non-linear finite element
techniques. The influence of geometrical, material and loading parameters on the impact
response is investigated using validated numerical models. Results are quantified in
terms of important impact response parameters and indicate that the foam filler
stabilizes the crushing process and thus improves the energy absorption capacity. The
superior performance of foam-filled conical tubes as impact energy absorbers is evident
from the results. The research information generated will be useful in developing
guidance towards the design of these devices in impact applications.

Dynamic computer simulation and energy absorption offoam-filled conical tubes under axial impact loading

Bio-inspired engineering design has drawn considerable attention in the recent years for its great structural and mechanical features. This study aimed to explore the energy absorption characteristics of a novel bionic-bamboo tube (BBT) structure subjected to axial crushing. The tubes with six different cross-sectional configurations were devised with inspiration of bamboo microstructure. The effects of rib shape and rib number were analyzed by using the finite element code LS-DYNA. The numerical results indicated that the BBT structures with the rib shape of “X” and the rib number of six exhibited the best crashworthiness. To further improve the energy absorption capabilities of these BBT structures, the multiobjective optimization was employed with respect to design variables of configurational structure, such as the rib angle of the “X” shaped cross-section, center distance and rib thickness. The response surface method (RSM) and multiobjective particle swarm optimization (MOPSO) algorithm were adopted to maximize specific energy absorption (SEA) while minimizing peak crushing force (PCF). The optimization results demonstrated that compared to the baseline design, the SEA value of the optimized BBT structure was further increased by 6.84% without sacrificing in peak crushing force.

Design of bionic-bamboo thin-walled structures for energy absorption

Foam-filled thin-wall structures exhibit significant advantages in light weight and high energy absorption. They have been widely applied in automotive, aerospace, transportation and defense industries. Quasi-static tests were done to investigate the crash behavior of the empty and polyurethane foam-filled end-capped conical tubes. Non-linear dynamic finite element analyses were carried out to simulate the quasi-static tests. The predicted numerical crushing force and fold pattern were found to be in good agreement with the experimental results. The energy absorption capacities of the filled tubes were compared with the empty end-capped conical tubes. The results showed that the energy absorption capability of foam-filled tube is somewhat higher than that of the combined effect of the empty tube and the foam alone. Finally, the crash performance of the empty and foam filled conical and cylindrical tubes were compared. Results from this study can assist aerospace industry to design sounding rocket carrier payload based on foam-filled conical tubes.

Experimental and numerical crashworthiness investigation of empty and foam-filled end-capped conical tubes

Sheet forming process of carbon fiber reinforced plastics for lightweight parts

The paper investigates collapse mechanisms and energy absorption capacity during the axial compression of the end-capped thin-walled circular aluminum tubes which are hollow or filled with polyurethane foam. An experimental technique is used to evaluate the crushing behavior of the circular tubes under compressive quasi-static strain rate. A numerical model is presented based on finite element analysis to simulate the crushing of circular tubes considering nonlinear response due to material behavior, contact boundary conditions and large deformation. The validated model using existing experimental results is used to evaluate the dynamic response in order to determine the dynamic amplification factor relating the quasi-static results to dynamic response. The experimental and numerical results are used to determine energy absorption capacity due to the plastic deformation of thin-wall tube and crushable foam. The performance of end-capped tubes is compared with non-capped tubes and it is found that maximum initial peak load can be controlled and convenient crash protection systems can be obtained using end-capped circular tubes.

Axial crushing analysis of end-capped circular tubes

Micromechanical analysis of stress relaxation response of fiber-reinforced polymers

Characterization of heterogeneous materials under shear loading at finite strain

Finite element analysis of thermoplastic composite plates in forming temperature

This paper investigates the micromechanical damage behavior of carbon-epoxy composite on the transverse tensile of representative volume elements (RVEs) with various fiber volume fractions. A new algorithm is developed to generate the random distribution of fibers in the RVE, and it is possible to create fiber distributions with high fiber volume fractions. The fibers and matrix are considered linear elastic and elastoplastic with progressive damage criterion, respectively. Fiber-matrix debonding and matrix crack are considered as the dominant damage modes. The normal cohesive properties distribution is applied for interfaces between fibers and the matrix in order to achieve a more realistic microstructure. To investigate the effect of the position of fibers with the weakest cohesive strengths, sensitivity analyses concerning the different arrangements of specific normal cohesive properties on the RVE’s strength are performed. Moreover, the effects of different damage parameters, such as random fiber distributions and various cohesive parameters on the overall damage behavior of the RVE, are described in detail. It is revealed that the application of a normal cohesive distribution sharply reduces the maximum strength of the RVE and shifts the strain of damage initiation point and crack propagation path.

Mohammad Tahaye Abadi

Papers

Axial crushing analysis of end-capped circular tubes

Micromechanical analysis of stress relaxation response of fiber-reinforced polymers

Characterization of heterogeneous materials under shear loading at finite strain

Finite element analysis of thermoplastic composite plates in forming temperature

Effect of interface properties on micromechanical damage behavior of fiber reinforced composites