The StressWave^TM Fatigue Life Enhancement Process

New method and tool for increasing fatigue life of a large number of small fastener holes in 2024-T3 Al alloy

“…As a result from the microeffect, the plasticity and the fatigue strength of the layers with modified microstructure are increased. The methods known as split sleeve, split mandrel [5], symmetric cold expansion [6,7] (united under the group of mandrel coldworking methods) and the stress wave method [8,9] produce an impressive macroeffect, while the microeffect is practically absent. FSHE creates both effects, but the benefit of this method is primarily due to the microeffect, as the macroeffect is significantly smaller in comparison with the one created by the mandrel coldworking and stress wave methods.…”

A finite element simulation of the spherical mandrelling process of holes with cracks

“…After drilling the hole, the residual circumferential normal stresses are compressive. The StressWave method [9] belongs to this group where the preceding impact is mechanical. According to second approach, first the hole is drilled and then it is subjected to cold expansion.…”

A Novel Closed-Form Calculation of the Stress Intensity Factor for a Crack in a Residual Stress Field

“…However, this method induces an asymmetric three-dimensional compressive residual stresses along the planar and through thickness directions at the hole [6]. A novel hole cold-working called StressWave TM (SW) has been recently developed to overcome the limitations of current coldexpansion techniques [7]. The process involves the controlled displacement of two co-axial indenters into the work piece, creating permanent dimples at the prospective hole location.…”