The effect of clamping stress on the fatigue strength of bonded high-strength steel interfaces

Fatigue experiments and finite element analysis of bolted/bonded double lap joints

“…Further loading causes the traction to be degraded according to the damage evolution equation, which can be linear, exponential or user-defined. After damage initiation, the tractions are defined as (1 ) , 0…”

“…A test method using a modified napkin ring specimen which combines shear and normal stresses was introduced [1][2][3][4]. The method allows for the characterization of interface properties with very welldefined boundary conditions.…”

“…Previously, static behaviour was successfully characterized by using the cohesive zone modelling (CZM) approach [2,4]. High-cycle fatigue behaviour was studied via a series of constant amplitude fatigue tests [1]. As a result, the fatigue strength at 2x10 6 cycles was measured under several clamping stress conditions by using the small sample staircase method [5][6][7].…”

“…The response of bonded/bolted hybrid joints is inherently a combination of the behaviour of bolted joints and adhesive joints. The fatigue failure mechanisms of the bonded and clamped interface were identified in [1]. It was observed that for areas under low clamping stress, the failure was governed by shear decohesion, which is failure related to the adhesive.…”

“…Through quasi-static simulations on the DLJ, the locations and magnitude of the maximum shear stresses in the bonded and clamped interface can be determined. The stresses at the interface are compared to normal stress/shear stress conditions that have been observed to correspond to the interface fatigue strength at 2x10 6 cycles [1].…”