Ported jacket for use in deformation measurement apparatus

A method of measuring deformation of a specimen, including:

• providing the specimen to be tested;
• enclosing the specimen within a jacket of elastomeric material having at least one opening and internally contacting the outer surface of the specimen;
• closing the opening by attaching a thin layer of substantially non-compressible material to the jacket portions surrounding the opening, placing the thin layer in contact with the specimen surface;
• and
• positioning a measurement device on the specimen so that the device contacts only the layer of substantially non-compressible material.

In a test apparatus for measuring deformation of a specimen, including:

• a frame for supporting the specimen and providing a load to the specimen, and a measurement device for measuring the deformation of the specimen, the improvement comprising:
• specimen containment means constructed of a compressible material for containing the specimen and having at least one opening;
• and
• a contact layer constructed of a substantially non-compressible material covering the opening and contacting a specimen in the jacket in the region of the opening and for receiving a portion of the measurement device through the opening.