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 of the coupon during fatigue testing. The propensity to fail at the gauge area is imparted by using a bow-tie-shaped coupon coupled with similarly shaped tabs. The test coupons 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, forming a pair of trapezoidal portions (one the mirror image of the other) connected by the gauge area. These trapezoidal portions of the test coupon include the regions where similarly trapezoidal tabs will be adhered to the front and back of the coupon. The test coupon has a minimum width in the gauge area and a constant thickness, and a height of the gauge area is no greater than 3% of a height of the test coupon.

主权项

1. A composite test coupon comprising:
a first trapezoidal portion having first and second straight tapered sides; a second trapezoidal portion having third and fourth straight tapered sides; and a gauge area disposed between and connected to said first and second trapezoidal portions, and having first and second radiused sides, said first radiused side being connected to said first and third straight tapered sides, and said second radiused side being connected to said second and fourth straight tapered sides, wherein the test coupon has a minimum width in said gauge area and a constant thickness, and a height of said gauge area is no greater than 3% of a height of the test coupon.