The DCPD method effectively correlates the electrical resistance of a specimen with the length of a growing crack. When the crack grows, the resistance changes. The DCPD method is useful in aggressive environments because it only requires that wires be welded or mechanically attached to the specimen. Recent scientific literature shows that DCPD can be used with ceramic specimens in addition to metallic specimens at high temperature because the electrical conductivity of certain ceramic materials increases significantly with temperature. MTS has software applications that calculate crack length using a DCPD method using your existing hardware or MTS supplied DCPD hardware.
Specimen gripping Gripping the specimen in aggressive environments is often problematic.
In corrosive but relatively low temperature environments, grips made of a corrosion resistant material such as stainless steel or Inconel can be used. In hot environments, a strong, hot corrosion resistant material such as nickel base or oxide dispersion strengthened superalloy must be used. Cryogenic testing requires grips that are strong and tough at cryogenic temperatures. MTS model 680.01 grips are designed specifically for high temperature tensile or low cycle fatigue testing in air. These grips are water-cooled and support button head or threaded specimens.