Apparatus and methods for material testing configured to apply a releasable clamping force to secure a crosshead

A material testing apparatus, comprising:

• guide means;
• sample holding means for holding a sample;
• force means for applying force to the sample;
• a crosshead arranged to support at least a portion of one or both of the sample holding means and the force means, wherein the crosshead is moveable about the guide means;
• automated clamping means configured to apply a releasable clamping force between the guide means and the crosshead to secure the crosshead at a location with respect to the guide means, wherein the automated clamping means comprises:
• at least one clamping member arranged to contact the guide means, wherein the clamping force is a friction force between the at least one clamping member and the guide means, and at least a portion of the at least one clamping member is arranged to extend from the crosshead to act as a lever for applying the friction force between the at least one clamping member and the guide means;
• and
• a linear actuator configured to apply a linear force (FL) generally perpendicular to an axis of the at least one clamping member for applying the clamping force, wherein the linear force (FL) from the linear actuator is translated into a torque force (FT) about a pivot point of the lever, such that the friction force applied is in dependence on the linear force (FL);
• and
• a controller configured to control the automated clamping means to apply the clamping force between the guide means and the crosshead.