Conewise linear elastic (CLE) materials are proposed as the proper gen
eralization to two and three dimensions of one-dimensional bimodular m
odels. The basic elements of classical smooth elasticity are extended
to nonsmooth (or piecewise smooth) elasticity. Firstly, a necessary an
d sufficient condition for a stress-strain law to be continuous across
the interface of the tension and compression subdomains is establishe
d. Secondly, a sufficient condition for the strain energy function to
be strictly convex is derived. Thirdly, the representations of the ene
rgy function, stress-strain law and elasticity tenser are obtained for
orthotropic, transverse isotropic and isotropic CLE materials. Finall
y, the previous results are specialized to a piecewise linear stress-s
train law and it is found out that the pieces must be polyhedral conve
x cones, thus the CLE name.