日本金属学会誌

J. Japan Inst. Metals, Vol. 40, No. 6 (1976),
pp. 644-649

Analysis of the Tensile Strength of Off-Axis Discontinuous Fiber Composite Alloys by the Finite Element Method

Kenzou Asaoka1 and Ishi Miura1

1Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Tokyo

Abstract:

The finite element method was used in the micro-mechanical calculations of the tensile behavior of a discontinuous off-axis (the loading direction is at an angle to the fiber axis) fiber composite alloys. The effect of the off-axis on the strength of the composite alloys was also discussed.
The mechanical properties of the matrix and the fiber were assumed to be those of aluminum and high Young's modulus materials such as precipitates, metal fibers and whiskers. The ratio of their Young's moduli, Ef/Em, was taken as 5. The fiber reinforcement was considered to be perfectly bonded in the matrix. The shear stress distributions at the matrix fiber interface, the stress distributions in the fiber, and the stress distributions in the matrix were investigated in various off-axis tensile stress directions.
Three possible failure mechanisms in a composite alloy with discontinuous unidirectionally-aligned fibers are postulated, viz. fiber failure at the maximum principal stress in the fiber, matrix fiber interface failure in shear at the maximum shear stress at the interface, or matrix failure at the normal stress. And the opperative mechanism was dictated for the strength of the composite with off-axis φ , which was compared with the criterion of the continuous fiber reinforced composite proposed by Kelly-Davies.
The results of these calculations showed that the interface might be fractured under a low off-axis tensile stress because of the shear stress acting on the fiber end. Thus the critical off-axis angle φ crit was smaller than that of continuous fibers. For the strengthning with discontinuous fiber, it is therefore essential to align the fiber in the tensile direction and also to prepare a composite alloy with a strong interface.


(Received 1975/11/25)

Keywords:


PDF(Free)PDF (Free)     Table of ContentsTable of Contents

Please do not copy without permission.