Shear Strength Measurement of AV119 Epoxy‐Joined SiC by Different Torsion Tests

Abstract

The results of an experimental investigation on epoxy‐joined silicon carbide tested in shear mode by seven different configurations of torsion tests are presented and compared to results obtained by asymmetric four‐point bending. All samples have been joined by an epoxy adhesive (Araldite AV119) chosen to obtain several joined samples in a reasonable time. Advantages and disadvantages of each configuration are discussed with the aim of finding a suitable method to measure the shear strength of joined components.

Torsional Shear Strength Tests for Glass–Ceramic Joined Silicon Carbide

“…The ideal configuration for a torsion test would be a thin joined ring, for example, two pipes butt joined and tested in torsion: unfortunately this configuration is difficult to handle with ceramic materials …”

“…The torsion tests were performed in a universal testing machine (ZWICK 100), where the load was applied until fracture occurred. The torsion load was applied using a rotating disk fixture with a wire equipped in the mechanical test frame . The cross‐head speed was 0.5 mm/minute with an estimated rotation speed of about 0.010 rad/minute.…”

“…Commonly adopted lap test methods do not properly measure shear strength: they give “apparent shear” resulting from a mixed state of stress including shear, bending, and tensile stresses. Because of the various complex stress states in different test configurations, a comparison of data obtained by different test methods is not possible, nor a comparison between different joining materials …”

“…Preliminary results suggested that this torsion test has a potential to evaluate the shear strength of joined components. However, it was demonstrated that in the case of semi‐brittle‐joining materials (epoxy adhesive), the measured torsion strength of fully joined hour‐glass‐shaped samples was higher than that of ring‐shaped hour‐glasses of the same diameter (Fig. ), due to the plastic contribution of the epoxy adhesive: in ref.…”

“…Different configurations of specimen to be joined for torsion tests: (a) from left to right: THG ‐4, TDHG and TRHG (as in ref. ) and (b) one joined sample.…”