Deformationcontrolled

Deformation-controlled refers to a testing or modeling approach in which deformation, displacement, or strain is prescribed and controlled, rather than the applied load or force. In practice, this means the experiment or simulation follows a specified deformation path while the resulting stresses, reactions, or force responses are observed or calculated. The term is often used interchangeably with strain-controlled, though some disciplines distinguish between controlling overall displacement versus controlling true material strain.

In experimental settings, deformation-controlled tests are implemented with actuators and feedback systems that enforce a prescribed displacement or strain rate. Universal testing machines and servo-hydraulic systems can operate in displacement control to produce predictable strain paths, measure stress responses, and determine material properties such as modulus, yield points, and failure behavior. Deformation control is especially useful for soft materials, composites, or delicate boundary conditions where force-controlled tests may induce undesirable instabilities or nonuniform loading.

In computational mechanics, deformation-controlled boundary conditions specify the prescribed displacement field over time, with stresses and reaction forces computed from the material model. This approach is valuable for studying material behavior along specific loading paths, evaluating constitutive models, or isolating path-dependent phenomena such as strain hardening or damage evolution.

Advantages of deformation control include direct access to a chosen strain path, improved repeatability for constitutive testing, and reduced risk of force overshoot. Limitations involve inability to impose arbitrary stress states, potential boundary-condition artifacts, and the need for precise actuation or accurate displacement measurement. Related concepts include load-controlled testing and strain-rate controlled methods.