Investigation in Shear Behavior of Intermetallic Composites Using V-Notched Beam Test Method

摘要

Nano-engineered intermetallic composites have been recently developed and identified as an emerging technology for a number of breakthrough downhole applications at Baker Hughes. This type of intermetallic composite is composed of particulate metallic phases with specifically designed intermetallic intergranular interphases, which may behave very differently from conventional metal-based composites and alloys. The customized design of these materials yields unique mechanical and chemical properties preferred for various downhole applications. To characterize the shear properties of the material that often needs special attention, a proven shear test method, the V-notched beam or losipescu shear test method (ASTM D5379), was used for the targeted materials. However, when this test method was applied to the selected intermetallic composite, complicated off-axial two-path fractures, rather than a desired pure shear failure mode, were observed. To investigate the failure mechanism and the effectiveness of the ASTM testing method, a full 3-D finite element model was created and investigated using an extended finite element method (XFEM). Based on the finite element analysis results and the additional shear tests of a reference alloy with similar base metal composition, the true material system-dependent failure mechanisms were identified and the test method was further validated. A special mechanical design guideline for this innovative nano-engineered intermetallic composite material was also recommended.