Prediction of Matrix Failure in Fibre Reinforced Polymer Composites

Table 3

Data from neat resin biaxial tests [8, 9] and errors with different prediction methods.

Resin	Stress applied*		Error with prediction method** (%)
	𝜎1	𝜎2	Equation (1)	Equation (13)	Max stress criterion
Type A	0.79	0.79	−36.7	−10.5	+21.0
Type B	0.84	0.50	−25.4	+2.3	+16.0
Type C	0.85	0.80	−39.4	−14.3	+15.0

*Expressed using the ratio of the yield stress in the biaxial test against that in the uni-axial tensile test.
**In each method, the yield stress from the uni-axial tensile test was used to determine the critical value for prediction of yield strength in biaxial tests. A “+” sign means overprediction and a “−” sign means underprediction.