Hu–Washizu principle

In continuum mechanics, and in particular in finite element analysis, the Hu–Washizu principle is a variational principle which says that the action

$\int _{V^{e}}\left[{\frac {1}{2}}\varepsilon ^{T}C\varepsilon -\sigma ^{T}\varepsilon +\sigma ^{T}(\nabla u)-{\bar {p}}^{T}u\right]dV-\int _{S_{\sigma }^{e}}{\bar {T}}^{T}u\ dS$

is stationary, where $C$ is the elastic stiffness tensor. The Hu–Washizu principle is used to develop mixed finite element methods. The principle is named after Hu Haichang and Kyūichirō Washizu.

Further reading

• K. Washizu: Variational Methods in Elasticity & Plasticity, Pergamon Press, New York, 3rd edition (1982)
• O. C. Zienkiewicz, R. L. Taylor, J. Z. Zhu : The Finite Element Method: Its Basis and Fundamentals, Butterworth–Heinemann, (2005).