PSI - Issue 48

Ilham Bagus Wiranto et al. / Procedia Structural Integrity 48 (2023) 65–72 Wiranto et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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experiments and material characterization. The sample was tested out under random loading conditions in order to investigate appropriate mechanical properties before determining its application. In this paper, the current research related to crashworthiness analyses using drop-weight impact events will be reviewed. The results of carbon fibre composite sandwich crashworthiness are also will be discussed. Finally, the opportunities for future studies in the area of CFRP crashworthiness will be illustrated. 2. Crashworthiness: experimental and analysis review Evaluating the crashworthiness of structures is very dependent on the experimental setup used in the study, which plays a crucial role. These experimental analyses involve subjecting test specimens to various types of loading conditions to understand their behavior and failure mechanisms under crash loading. In this section, experimental studies that have been conducted to investigate the crashworthiness of composite materials, focusing on the methods used to carry out the experiments, the test configurations, and the results obtained will be reviewed. Essentially, the axial, oblique, lateral, and bending loading conditions are the most frequent ones to investigate the crashworthy design structure. The aim of this review is to provide a comprehensive understanding of the experimental techniques employed in the field of crashworthiness and to highlight the recent developments in this area. When a crash occurs, the failure of composite crushed tubes or structures is caused by intricate micro-structural mechanisms. Table 1 outlines the definitions and formulas for several significant crashworthiness and absorption indicators in the composite structures. Specific energy absorption (SEA) and energy absorption (EA) capacity parameters have been frequently cited as the primary indicators in numerous crashworthiness investigations involving composite structures. Table 1. Definition and formulas of crashworthiness indicators used by the majority of researchers for composite structure. Parameter Equation Definition

M EA c

Ratio of the energy absorption to the crushed mass (Mc) of the composite structure Integration of the crushing force ( ) with respect to the displacement x over the crushed structure distance c Total energy absorbed divided by the crushed structure distance obtained from the force-displacement curve Ratio of the mean crushing force to the peak crushing force p

Specific energy absorption (SEA)

∫ F(x)dx dc 0 d1c ∫ F(x)dx dc 0 ∫ F(x)dx dc 0

Energy Absorption (EA)

Mean Crushing Force (MCF)

Crush Force efficiency (CFE)

2.1. Crashworthiness facility In crashworthiness testing, drop testing is a common experimental method used to evaluate the impact response of structures. This method involves dropping a structure from a predetermined height onto a rigid surface while measuring the response of the structure. The drop test facility is a critical component of such experiments, providing a controlled environment for the impact test. In recent years, several advancements have been made in the design and operation of drop test facilities, aimed at improving their accuracy, repeatability, and safety. In this sub-section, we review the current state-of-the-art in drop test facilities, discussing their design principles, capabilities, and limitations. Table 2 shows the previous studies using drop tests and sensors involved. In addition, the schematic of experimental setup of those studies are shown in Fig. 2. 2.2. Structural Rigidity of thin-wall structure The effect of various geometries on the specific energy absorption in crashworthiness can vary significantly. Generally, it is observed that different geometries result in different energy absorption capabilities, with some geometries providing higher specific energy absorption compared to others.