Crashworthiness design of a steel–aluminum hybrid rail using multi-response objective-oriented sequential optimization

© 2017 Elsevier Ltd Hybrid structures with different materials have aroused increasing interest for their lightweight potential and excellent performances. This study explored the optimization design of steel–aluminum hybrid structures for the highly nonlinear impact scenario. A metamodel based multi-response objective-oriented sequential optimization was adopted, where Kriging models were updated with sequential training points. It was indicated that the sequential sampling strategy was able to obtain a much higher local accuracy in the neighborhood of the optimum and thus to yield a better optimum, although it did lead to a worse global accuracy over the entire design space. Furthermore, it was observed that the steel–aluminum hybrid structure was capable of decreasing the peak force and simultaneously enhancing the energy absorption, compared to the conventional mono-material structure

On the crashworthiness performance of thin-walled energy absorbers: Recent advances and future developments

Over the past several decades, a noticeable amount of research efforts has been directed to minimising injuries and death to people inside a structure that is subjected to an impact loading. Thin-walled (TW) tubular components have been widely employed in energy absorbing structures to alleviate the detrimental effects of an impact loading during a collision event and thus enhance the crashworthiness performance of a structure. Comprehensive knowledge of the material properties and the structural behaviour of various TW components under various loading conditions is essential for designing an effective energy absorbing system. In this paper, based on a broad survey of the literature, a comprehensive overview of the recent developments in the area of crashworthiness performance of TW tubes is given with a special focus on the topics that emerged in the last ten years such as crashworthiness optimisation design and energy absorbing responses of unconventional TW components including multi-cells tubes, functionally graded thickness tubes and functionally graded foam filled tubes. Due to the huge number of studies that analysed and assessed the energy absorption behaviour of various TW components, this paper presents only a review of the crashworthiness behaviour of the components that can be used in vehicles structures including hollow and foam-filled TW tubes under lateral, axial, oblique and bending loading

DEVELOPMENT OF HYBRID AND NON-HYBRID COMPOSITE BODY ARMOR PLATE FOR BALLISTIC PROTECTION

In this work, a new Bullet Guiding Pocket Armor Plate (BGPAP) was developed, with a target to maximize the ballistic protection by containing the bullet between the layers. To this end, experimental and numerical programs have been carried out. Accordingly, the study has been divided into three phases concerning the problem solution to improve the energy absorption capability of the body armor plate without complete penetration. In phase-I, the effects of material stacking sequence and geometrical configuration on the ballistic behavior of hybrid and non-hybrid body armor plates were studied. Three different materials have been used, carbon fiber, Kevlar and date palm fiber. In phase-II, the effect of conical angles on the quasi-static crushing behavior of bullet guiding pockets was studied, in which five conical angles were tested, ranged between 35° and 55° with an increment of 5°. Two filament materials have been employed to fabricate the specimens. These are carbon fiber and Kevlar. The findings of the preceding phases were used as input for phase III, in which the new Bullet Guiding Pocket Armor Plate (BGPAP) has been developed. Finite Element software package, namely ANSYS/LS-DYNA has been used to simulate the ballistic behavior of tested body armors. Material stacking sequence has affected significantly the energy dissipation mechanism, energy absorption capability of hybrid composite body armor. Body armor with [CFRP10/KFRP30] material sequence displayed the highest energy absorption capability and passed the ballistic real shooting test. On the other hand, body armors with [CFRP4/KFRP6]4 had displayed poor energy dissipation mechanism and didn’t pass the ballistic real shooting. Incorporating the untreated date palm natural fiber composites in the material sequence of body armor displayed promising ballistic behavior, although didn’t pass all the three-trial real shooting test. Introducing bullet guiding pockets in the design of body armors has a significantly effect on their sliding crush behavior. Similar sliding crush behavior trends have been observed for both CFRP and KFRP bullet guiding pockets have been found similar. Designing the bullet guiding pockets within the CFRP layers displayed the highest energy absorption capability compared with KFRP layers. Bullet guiding pocket conical angles has been optimized, and specimens with 50° had the highest specific energy absorption capability in both CFRP and KFRP. The newly developed BGPAP showed an excellent ballistic performance against 9 mm bullet with BFS 19.6 mm. The newly developed BGPAP showed 16% reduction in weight compared to the hybrid [CFRP10/KFRP30] armor plate.Qatar National Research Fund (a member of Qatar Foundation) through the National Priorities Research Program NPRP # 6-292- 2-127