## 1 Introduction
To be in accordance with the already active standards for damage resistance and compressive residual \begin{table}
\begin{tabular}{c c c} \hline \hline
**Fixture** & **Improvements** & **Shortcomings** \\ \hline University of London & Variable specimen width & Local tearing of the laminate \\ (1999) [15; 16] & and thickness & Does not allow frond formation and \\  & Adjustable knife-edge supports & curling at the tip \\ Department of Energy of & Splaying failure mode & Only one failure mode \\ the United States & No need of triggering specimen due to & The unsupported condition does not \\ (2003) [17] & the curved contact profile & produce reasonable results \\  & Plate thickness can vary between 1.2 & Fully constraint specimen \\  & and 10 mm & Requires extensive calibration \\ Engenuity (2005) [11] & Reduced friction by Delrin sliders & Might jam due to large fronds \\  & Stable crushing, both QS and dynamic & and debris \\  & Adjustable unsupported height with & Tearing at the edges \\ University of Washington & knife-edge supports & Half scale specimen (\(76\times 51\) mm) \\ (2009) [14] & Allows studying the effects of & Upper plate specially designed for \\  & various parameters & 2 mm thick specimen \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of some of the fixtures already developed and reported in the literature [14]. strength measurement of composite flat plates, this fixture was designed to support specimens with the same dimensions of \(150\times 100\) mm. The position of supporting columns could be changed to study various unsupported heights and how they affect the crushing of the specimens. Cylindrical columns with a 10 mm diameter were used to avoid tearing of the test elements. The gap between the supporting plates allows the use of a high-speed camera and the observation of the energy absorption mechanism and crack propagations while crushing the elements. This new design allows up to 50 mm of material to be crushed without jamming due to the fronds and debris. Having this large crushable length allows researchers to study higher impact energies and crushing mechanisms far from triggers used for the initiation of the steady crushing. Since the early days of the crashworthiness evaluation of composite structures, it was observed that the correct trigger mechanism is mandatory to initiate the progressive crush and maximize energy absorption [19]. Some researchers have used external triggers like chamfers in the fixtures [17; 20] or metallic plugs [21], while others have studied internal triggers like less stiff and different stacking layers of fibers in the crush front [6; 22] or different geometries such as steeple or chamfer [23], v-shaped [24], sawtooth [14], or other geometries. It was reported that sawtooth triggers allow the symmetric progressive crushing of the flat specimens with both splaying of the outer layers and fragmentation of the inner ones [14]. Thus, this trigger mechanism was chosen for the current research study. In this study, with the help of simulations done with Altair HyperWorks for design and optimization purposes, a newly developed anti-buckling fixture was manufactured. Experimental tests were used to study the robustness of this new fixture. The results of experimental tests allow a better understanding of the different failure modes and identify the parameters needed for the mathematical criteria used to describe the related crashworthiness of composite plates. Different testing conditions were designed to carry out a comprehensive study assessing the repeatability of the tests and the reliability of the results.