Abstract:
The effect of clamping on the fatigue strength of joints in aluminium alloy is investigated experimentally. Tests on Z-section stringers connected to long, slotted cleats give an endurance for tightly clamped joints about nine times that for unclamped joints. Tests of bolted joints in aluminium alloy sheet material show still greater improvement for very tight clamping. In both series of tests, the clamping tends to cancel the weakness in fatigue of a loaded hole. Tight clamping is considered to have many applications in design of aircraft joints from the standpoint of fatigue strength.
