Problem M21
a) A tensile specimen is made of an epoxy (a thermosetting polymer). It is loaded in the z
direction to a stress of 100 MPa. Assuming that the epoxy remains elastic, what are the
resulting strains in the x, y and z directions? The Young's modulus of the epoxy is 3 GPa and
the Poisson's ratio is 0.3
b) A thin (t<<R) layer of an epoxy adhesive is used to join two silicon carbide bars of circular
cross-section, as shown below. An axial (z direction) tensile stress of 100 MPa is applied to
the joint as shown. Calculate the axial strain (ezz) in the adhesive. The Young's modulus of
the epoxy adhesive is 2 GPa, the Poisson's ratio is 0.3. The Young's modulus of the SiC is 450
GPa and the Poisson's ratio is 0.16. State any assumptions/approximations that you make in
solving this problem - note that you may not be able to achieve an exact solution but you
should aim to obtain a good approximation. Hint: think about the transverse strains in the
adhesive (e and eyy ).
xx
2R
t
Adhesive
SiC
x
y
z
100 MPa
100 MPa
100 MPa
100 MPa
Perspective View
Cross-Section
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