Abstract
Ultra-high-molecular-weight polyethylene (UHMWPE) fiber laminate is currently widely used in ballistic protection for its exceptional physical and mechanical properties. However, the dynamic compressive mechanism of UHMWPE laminate remains poorly understood. Therefore, the stress–strain relationship, the influence of different thickness, area, and shape, and the maximum stress and fracture stress are studied in both out-of-plane and in-plane directions under quasi-static and dynamic loading using a universal test machine, Split Hopkinson pressure bar (SHPB), and high-speed camera. Furthermore, numerical models with cohesive elements are developed. The results indicate a dependency on strain rate and loading direction. Firstly, the stress–strain curve of dynamic testing can be divided into different zones according to different loading directions and strain rates. Secondly, with the increase of the strain rate in the dynamic testing, the maximum stress and fracture stress increase as well; relatively speaking, the fracture stress in the out-of-plane direction is greater than the fracture stress in the in-plane direction. Thirdly, both experiment and simulation indicate that the thickness does not influence the modulus clearly the in out-of-plane direction but influences the modulus in the in-plane direction. Fourthly, the fracture stress of dynamic testing is higher than the fracture stress of quasi-static testing in both directions. Finally, the numerical results show good agreement with the experiment in terms of the maximum stress and failure form.
Highlights
The combination of ductile materials and brittle materials can result in a lightweight material, which prevents penetration and effectively protects the human body [1,2]
The results showed that the peak stress, results showed that the yield stress, strain at yield stress, and modulus all increased with the compressive modulus, and specific fracture strain energy density increased with the increase in increased strain rate
The results showed good agreement with the experiment conducted by Reference [33] using the digital image correlation (DIC) technique
Summary
The combination of ductile materials and brittle materials can result in a lightweight material, which prevents penetration and effectively protects the human body [1,2]. Fiber-reinforced composite laminate is suitable for protection against higher-lethality fragmentation threats [3]. Fiber-reinforced laminate behind ceramic could perform significantly as a ductile material in protecting a human torso [4–6]. Fiber-reinforced laminate could be made into a protective helmet as a weight-critical application [3]. Ultra-high-molecular-weight polyethylene (UHMWPE) fiber has exceptional physical and mechanical properties, such as high impact resistance, high wear resistance, high chemical resistance, and low friction coefficient [7]. It is widely used in ballistic protection, as well as the aerospace and military industries [8,9]. In typical UHMWPE ballistic composite sheets, unidirectional (UD) layers of fibers are impregnated with a thermoplastic matrix, and they are stacked in 0◦ /90◦
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