Mechanical Deformation Stages

The common types of mechanical deformation stages are tension, compression, and bending. These types of stages designed for use in the SEM are conunercially available from the SEM manufacturers or companies making accessories (Appendices V and VI). Typically, the tension and compression stages are 

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Equilibrium tests at the local deformation stage of a sample provide adequate changes of external forces to internal efforts of a material to resist with corresponding static development of the main crack. These tests are most appropriate when using bending or tension of the samples, because the fracture process will be defined by development of a unique breakaway type of crack, which allows determination of the actual surface area of the fracture. This means that the tests correctly provide the real physical processes of fracture of a concrete and the principles of nonlinear fracture mechanics with traditional mechanical characteristics of concrete and allows determination of a set of power and energy parameters of the material fracture. 

Isaacs and coworkers measured the distribution of current density on scribed, painted zinc-coated steel during early stages of exposure in sodium chloride and sodium sulfate solution [142], Samples were electroplated steel and steel with hot-dipped 55% A1 —1.6% Si-balance Zn alloy. Different kinds of defects such as shallow scratches to the coating, deep scratches to the underlying steel, and those after mechanical deformation of the coated surface were prepared. The current distributions in the defect area were dependent on the kind of scratch that was produced and the change with the time of exposure in the NaCl solution. 

In contrast to the aerospace industry (see Aerospace applications), conditions prevailing in automobile manufacture dictate that pre-treatments (see Pre-treatment of aluminium) should have short process times and be tolerant of production variables. The surfaces produced should retain adequate bonding properties during extended storage under poorly controlled conditions. The surface may need to be sufficiently conductive to permit weld-bonding techniques. Pre-treatments applied at the coil stage must be compatible with mill oils and press lubricants, and withstand mechanical deformation in the press. 

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