Design and analysis of hard body armour composite mould system

The development of lightweight and low cost of hard body armour is under on-going attention by both manufacturers and users. In general, most hard body armour is made from metal, ceramic or composite. There are various methods to develop hard body armour such as manual layup, compression, resin transfer, slip casting, sand casting, hot pressing and injection moulding. However, for natural based reinforced composite where the reinforcement material is in powder or particulate form, such methods have to be specifically modified to achieve workability. This study presents a systematic design and fabrication process on hard body armour by using compression moulding method, where coconut shell powder was used as the reinforcement material in the composite system. Concept generation method was applied on developing the conceptual mould design. Three conceptual mould designs were proposed for flexible and hexagonal type of hard body armour. Based on the analysed data using weighted design method, the durability and manufacturability aspect were found as significant criteria to develop the mould. Further analysis such as fatigue life estimation was done to evaluate the durability, while machining time to measure the manufacturability on every concept design. Based on finite element analysis, hexagonal mould design number 3 was selected for prototype development due to its superior maximum stress of 33.7 MPa and total deformation of 10.72×10-6 m at compressing load of 784.8 kN, respectively. Meanwhile, flexible mould design number 3 was selected for prototype development due to its maximum stress value recorded and total deformation of 33.71 MPa and 4.6125×10-6 m, respectively. The fabricated hexagonal and flexible armour panels were subjected to ballistic test according to the regulatory standards. From the results, hexagonal armour panel with areal density 27.2 kg/m2 has a significant ballistic resistance to 9 mm FMJ ammunition impact which is equivalent to protection NIJ Level IIIA. Meanwhile, flexible armour panel with areal density 22kg/m2 also equivalent protection NIJ Level IIIA.