It was believed after the reason analysis that the blowhole defect was caused by the gas evolution of sand cores after being heated and the improper pouring system design which leading to the gas immixture.

Base d on the f ormation mechanism of pinhole defect in ductile castings, the production process of the bump housing and impeller of the oil transfer pump, which had been rejected totally due to severe pinhole defect, was improved including:(a) reducing moisture content of the molding sand from 7% to 5%;(b) adding 7.

In allusion to leakage blockage method by sticking of pore defect, the calculation process of toughness stress strength factor in the glue interface is given through the bulge test model analysis, and the critical bulge radius of split crack inter-cohesion break of epoxy resin glue is evaluated by means of brittle break criterion of break mechanics.

We firstly explained that the electromagnetic wave emitted from the source under the condition of far field is approximately the plane wave, which vertically downwards; and then under the condition of far field, we detail in studied the CSAMT response characteristics when there are different types of the hole lacuna in depth, in size, in shape, in silting (mud silting.