Moving punch on a highly orthotropic elastic layer

Summary An analytical solution was given to the problem of a long rigid punch moving rapidly on a strip of a highly orthotropic material. This elastic layer rests in turn on a rigid frictionless foundation. Obviously, the problem presents a lot of interest from the view-point both of geophysical and mechanical sciences. The solution was effected by means of integral transforms and the Wiener-Hopf technique. Asymptotic results were obtained valid near the edge of the moving punch.With 3 Figures     

Biaxiale Ermüdung reibrührgeschweißter Strukturelemente

Biaxial fatigue of friction stir welded stiffened panels Within the framework of the European WelAir project, cruciform specimens made from stiffening FSW overlap joints were fatigued in the DLR biaxial test rig. To resemble the loading situation of pressurized fuselage structures, proportional loading without any phase shift, but with different load ratios λ between the loading components in both directions was applied.Natural crack initiation and subsequent crack growth were governed by the stiffness gradient caused by introducing the stringer. Cracks initiated and propagated at run‐in and run‐out locations in a direction perpendicular to the weld seam. The shortest fatigue life was observed for uniaxial loading in welding direction (λ = 0). An additional stress component perpendicular to the joint line (λ > 0) resulted in a higher number of cycles to failure. Similar to single stringer panels, increasing the load ratio also increased the number of cycles to failure for FSW clip‐stringer structural members, but additionally gives a different location of the fatal crack.