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Fracture crack on material strength

Source:   Date:2014-10-28 15:46:34   Views:

If the sealer material is an isotropic material, and no internal cracks exist, when the material is subjected to the action of foreign force, the force transmitted in the material is homogeneous, i.e. the material in the various parts of the force is the same. When the surface or inside the material cracks, the crack tip region will produce local stress concentration. In the absence of uniform stress cracks in the flow line at this time the crack tip attachment highly intensive. Although this concentration is only partial, and leave a little distance the crack tip stress distribution tends to be normal again, but the stress concentration at the crack tip attachment, will make the closure of all material actual breaking strength values ??are much lower than the original theory of fracture strength value, so that the situation was not supposed to have problems also become dangerous. The radius of curvature at the crack tip stress concentration is closely related with the crack tip, the more sharp crack, the higher the degree of stress concentration.
For example, through the presence of an intermediate crack oval ellipse major axis 2a, minor axis 2b, subjected to a uniform tensile stress in a single phase.
According to the traditional view of the breaking strength, when the maximum stress at the crack reaches the end of the theoretical material of the fracture strength values??, the material will fracture.
As can be seen, when the solid has a very sharp cracks exist, the actual breaking strength of the solid material is much lower than the theoretical fracture strength. When the stress reaches. Value, the crack initiation, crack length 2a leaving the increase, so that they make. Decreases, the crack continues to expand, finally leading to the closure of all solid material fracture, so it is unstable crack growth conditions.