Experimental failure investigation for a titanium metal matrix composite with +45° and ±45° fibre orientations

Abstract

This paper presents the results of micromechanical failure analyses of titanium metal matrix composite shafts, under cyclic torsional loading. Two different fibre orientations were used to investigate the failure mechanisms, namely þ45 and AE45 fibre orientations. The fracture surfaces, after fatigue testing, were examined using a scanning electron microscope. Evidence was found of the existence of both ductile failure which occurred in the matrix material and brittle failure which occurred in the fibres. These modes of failure both played important roles in the overall shaft failure for a þ45 fibre orientation. In the case of the AE45 fibre orientation, failure of the matrix, on the plane of the þ45 fibres, was the main factor which influenced the fracture of the shaft.

Elasto-plastic finite element analysis of titanium metal matrix composite shafts under torsional loading

“…Figure 13 shows the stress distribution obtained for the case of frictionless contact. The fibre volume fraction is 35% and the tensile loading is 859 MPa, as described in Hyde et al 3 This is similar to the loading experienced in the TiMMC layer of a shaft which was tested under fatigue loading conditions, described in Hyde et al 15…”

“…In addition, surface-to-surface contact conditions are prescribed at the fibre-matrix interface. The loads are chosen to approximately represent the torsional shaft loading, as explained in Hyde et al 3 Unit cell analysis for the 645°fibre orientation Unit cell geometry. With regard to the 645°fibre directions, illustrated in Figure 7, a unit cell can be devised, as shown in Figure 8.…”

“…In addition, surface-to-surface contact conditions are prescribed at the fibre–matrix interface. The loads are chosen to approximately represent the torsional shaft loading, as explained in Hyde et al 3…”

“…1 Micromechanical failure analyses of TiMMC shafts under cyclic torsional loading for two different fibre orientations (+45° and ±45°) were used by the present authors to investigate the failure mechanisms of the shafts. 3 However, the understanding of the elasto-plastic behaviour of TiMMC shafts, under torsional loading, using finite element (FE) simulation, for example, is still limited.…”

Modeling and prediction of fatigue life in composite materials by using singular value decomposition method

“…It is generally known that materials may experience failure at a stress level lower than their static strength when subjected to dynamic loadings. [1][2][3][4][5][6][7][8][9][10] In other words, applied loads cyclic in nature may reduce the strength of materials such as metals, plastics, and composites. Estimation and prediction of the degree of damage after loading is one of the most important design characteristics as this knowledge results in a prudent, optimum, and safe structure.…”