Design, manufacture, and test of lightweight composite sandwich helmets

This paper summarises work undertaken on the design, manufacturing development, and impact testing of a lightweight composite aircrew helmet. Kull details are given on the double diaphragm forming process, developed at DERA, which has been extensively used (o manufacture the complex, doubly curved layers that form the final helmet assembly. Manufacturing options for the development of a Torm Fittingʹ foam liner arc also included, as are developments in the foam liner press moulding processes. Results from an extensive impact test programme conducted on fully assembled shell samples arc provided, illustrating good energy management during test. Some redundant material was apparent from the results, hence further mass reduction is possible. Modification of the layer deformation sequence is also required. However the sandwich shells met all impact test requirements. Correlation of the impact test data and helmet damage crosssections has allowed recommendations to be made regarding improved design and manufacture of the layered construction. Predictions based on these improvements show the final helmet mass should be ~750g, excluding breathing systems and communications.