SELECTING THE RIGHT GRIPS AND JAW FACES

Hydraulic Wedge Grips for Fatigue

Each grip functions independently of the other. An external hydraulic supply provides pressure to both open and close the grips. When gripping pressure is applied, the relative vertical position of the specimen/jaw faces remains unchanged to prevent generation of specimen load during the gripping process. Once the grip faces contact the specimen, the hydraulic pressure produces a vertical force on the grip head. The grip force will remain constant as the design automatically compensates for specimen thickness changes.

• Type of loading: static or dynamic, reverse stress

• Specimen material: metallics, plastics, composites

• Specimen geometries: round section (not buttonhead) or flat specimens with or without shoulder tab

Mechanical Wedge Grips for Fatigue

Each grip is mechanically operated. Gripping force is applied via movement of the grip body relative to the wedge shaped jaw faces. This movement is induced by the tightening of four socket cap screws on the underside of the grip head. Each jaw face is located in the grip body by two extension springs, which allow the jaw faces to release the specimen after testing. The grip body wedge area is fitted with jaw guides to ensure that the jaw faces remain square to each other and to the specimen.

• Type of loading: static or dynamic, reverse stress

• Specimen material: metallics, plastics, composites

• Specimen geometries: round section (not buttonhead) or flat specimens with or without shoulder tab