Material testing system having improved hydraulic wedge clips

1. A material testing system comprising:

a load frame comprising:

a base positioned on a support surface,

a main actuator supported by the base and below a lower attachment fixture that is vertically actuated by the main actuator, and

an upper fixture that is held at a distance from the lower attachment fixture; and

at least one hydraulic grip that receives one end of a test specimen and that is positioned between and attached to one of: (i) the lower attachment fixture and the upper fixture and comprising:

a fixture body having a wedge recess,

a pair of hydraulic grip wedges received in opposition within the wedge recess, each hydraulic grip wedge having a pair of vertical wedge retention spring holes that are perpendicularly intersected respectively by a horizontal retention bolt hole,

four retention springs having one end attached to the fixture body and another end extending upward respectively in the vertical wedge retention spring holes,

a cable engaged to the other end respectively of each extension spring and extending out of the corresponding hydraulic grip wedge, enabling manual extension of the respective retention spring,

at least two spring retention bolts received respectively in the horizontal retention bolt holes to attach to the other end of the wedge retention spring during extension by the corresponding cable, and

four or more cable clips that are respectively attached at one end to a lateral side of one of the pair of hydraulic grip wedges and engaged at another end to a corresponding cable to maintain the cable in a noninterfering position.

2. The material testing system of claim 1 , wherein the load frame further comprises:

a pair of vertical columns extending upwardly from the base,

a crosshead received for vertical movement on the pair of vertical columns and lockable at a selected vertical position on the pair of vertical columns that corresponds to a length of the test specimen, and

a pair of hydraulic linear actuators attached between the base and the crosshead to position the crosshead to the selected vertical position.

3. The material testing system of claim 1 , wherein the four or more cable clips each comprise an elongate strip having an aperture at both ends, one aperture attachable by a fastener to the corresponding lateral side of the one of the pair of hydraulic grip wedges, vertically positioning a first portion into contact with the corresponding lateral side, another portion of each cable clip bent at an acute angle away from a plane of the corresponding lateral side.

4. A method comprising:

attaching a fixture body of a hydraulic grip to one of a lower attachment fixture atop a main actuator and an upper attachment fixture attached to a crosshead of a load frame;

attaching four wedge retention springs to a recess of the fixture body;

passing respective one or more cables attached to each wedge retention spring through a corresponding vertical wedge retention spring hole in one of a pair of hydraulic grip wedges;

with a respective wedge retention spring extended in the wedge retention spring hole by manual actuation of a corresponding cable;

inserting a retention spring retention bolt through a horizontal bolt hole that intersects the vertical wedge retention spring hole;

attaching one end of a cable clip respectively to each lateral side of the pair of hydraulic grip wedges;

engaging another end of the cable clip to a corresponding cable to maintain the cable in a noninterfering position;

engaging a test specimen between the pair of hydraulic grip wedges; and

actuating the main actuator to materially test the test specimen.

5. The method of claim 4 , further comprising:

actuating a pair of hydraulic linear actuators that are attached between a base of the load frame that support the main actuator and the crosshead to position the crosshead to a selected vertical position on a pair of vertical columns attached to the base, the selected vertical position corresponding to a length of the test specimen; and

locking the crosshead to the pair of vertical columns at the selected vertical position prior to actuating the main actuator to materially test the test specimen.