MACLOCYCLE FATIGUE OF STRUCTURAL ELEMENT UNDER SOFT LOADING.

In the article the method of calculation of capacity for work construction element of low – cycle deformation diagrams with considering of cyclic instability and unilateral accommodation of plastic deformation.

ON ADHESIVE THEORIES IN MULTILAYERED INTERFACES, WITH PARTICULAR REGARD TO "SURFACE FORCE APPARATUS" GEOMETRY

Adhesion is a key factor in many tribological processes, especially wear. We generalize a recent formulation for the indentation of a multilayered material using an efficient integral transform method, to the case of adhesion, using a simple energetic transformation in the JKR regime. Then, we specialize the study for the geometry of the Surface Force Apparatus, which consists of two thin layers on a substrate, where the intermediate layer is softer than the other two. We find the pull-off force under "force control" (i.e. for "soft" loading systems), as well as under "displacement control" (i.e. for "rigid" systems), as a function of the geometrical thicknesses and material properties ratios, and the method is fully implemented in a fast Mathematica code, available to the public (see Appendix).

Bending of Superelastic Wires, Part II: Application to Three-Point Bending

The constitutive relationship between applied pure bending moment and the resulting curvature of a few superelastic alloy wires is applied to the three-point bending problem. Three-point bending experiments on hard and soft loading machines are described. The relationship between the applied deflection and the resulting force in three-point bending is calculated from a nonlinear Euler-Bernoulli rod theory. A numerical procedure used to solve the three-point bending problem for both loading and unloading is briefly described and numerical results are compared with experiment.

Finite Element Analysis of the Diametral Test of Polymer Moldings

A finite element analysis of the diametral test is presented and the results are compared with an elastic analysis and with diametral tests of molded pyrrone disks. Both the elastic and the finite element analysis gave similar stresses for points near the center of the disk. Near the points of loading, however, the elastic analysis gave infinitely high stresses whereas the finite element analysis gave high but finite stresses. A simulated fracture was made using the finite element analysis. The fracture began at the center of the disk and propagated toward the loading points. As the fracture approached the loading points, the finite element analysis indicated the formation of four secondary fracture sites in the disk. These sites were a normal development for a soft loading system. The existence and location of the secondary fracture sites was confirmed by diametral tests of molded pyrrone disks.