OPTIMISATION OF A CRUCIFORM TEST SPECIMEN FOR BI-AXIAL LOADING OF FIBRE REINFORCED MATERIAL SYSTEMS

Experimental investigation of fibre reinforced composites was predominantly performed using uni-axially loaded specimens. However, composites are often subjected to complex multi-axial loadings in service and consequently, experimental investigation should consider bi-axial tests. For this reason a bi-axial testing facility for planar cruciform specimens was developed. A valid and useful bi-axial test avoids failure in the uni-axially loaded arms and gives a large region of uniform strain in the bi-axially loaded zone, conditions which are not easily obtained simultaneously. To be able to select a suitable geometry, finite element simulations investigating the influence of various parameters in combination with experiments on different geometries were performed. 1