Coupon geometries that induce failure in gauge area of composite fatigue test coupons

摘要

A coupon geometry that reliably fails in the gauge area (20) of the coupon during fatigue testing. The propensity to fail at the gauge area (20) is imparted by using a bow-tie-shaped coupon (10) coupled with similarly shaped tabs. The test coupons (10) have a bow-tie-shaped profile with tapered sides that converge as they extend from the opposing ends of the coupon to the gauge area (20), forming a pair of trapezoidal portions (16 and 18) (one the mirror image of the other) connected by the gauge area (20). These trapezoidal portions (16 and 18) of the test coupon (10) include the regions where similarly trapezoidal tabs will be adhered to the front and back of the coupon. The test coupon (10) has a minimum width in the gauge area (20) and a constant thickness, and a height of the gauge area (20) is no greater than 3% of a height of the test coupon (10).