Energy-Absorption Behaviors of Glass Fiber Reinforced Plastic (GFRP) Plates with Hemispherical/Corrugated Force-Multipliers

In the present study, the behavior of hemispherical glass fiber-reinforced plastic (GFRP) energy-absorbers under applied transverse load has been investigated experimentally and numerically. A thermosetting general purpose polyester resin, along with bi-directionally woven E-glass fiber mats, has been used for the fabrication of the test specimens. Previously a limited number of studies were reported for hemispherical features made of composite laminates with fabrics based on randomly oriented chopped glass fibers. A motivation behind the current study is that woven fabric mats with continuous bi-directional strands can be considered as more reliable in terms of consistency of properties when compared with chopped strand mats. Additionally, the current concept of dome-shaped composite entities has been explored for vehicle safety applications, which has not been done earlier. The most basic configuration considered here is a single hemispherical GFRP cup with plane flanges and straight edges. The behavior of this feature is initially investigated experimentally and numerically under quasi-static compressive loading condition. It may be noted that for numerical simulation, the explicit LS-DYNA solver is used. The study for a single sphere is then extended to a monolithic configuration containing four similar hemispherical elements in a 2 × 2 square grid. It has been found that the crush load for the 4-hemisphere configuration increased by a factor of about 6 as compared to the single hemisphere with a similar implication on energy absorption. Thus, the present class of laminated composites with hemispherical features can be viewed as ‘force-multipliers’; for a given diameter of a hemisphere, the strength and energy-absorption capability of the system can be enhanced as required by providing the right number of hemispheres. It is also shown, with the aid of simulation, that composite laminates with multiple dome-shaped or corrugated features can be a potential countermeasure for vehicle impact safety design.