Material testing system having improved hydraulic wedge grips

{
  "publication_number": "US12216093B1",
  "country": "US",
  "kind": "B1",
  "title": "Material testing system having improved hydraulic wedge grips",
  "abstract": "A material testing system that uses at least one hydraulic grip is improved with cable clips that are attachable to a respective lateral side of each hydraulic grip wedge. Each cable clip has another end that extends to engage a cable(s) extending from a corresponding wedge retention spring hole. The cable(s) enable manual extension of a wedge retention spring for engagement and disengagement from the hydraulic grip wedge. The cable clip maintains the cable in a noninterfering position during operational use of the material testing system.",
  "claims": [
    "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 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 wedge retention spring holes that are intersected respectively by a retention bolt hole, four retention springs having one end attached to the fixture body and another end extending upward respectively in the 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 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. The material testing system of claim 3 wherein each of the four or more cable clips having an aperture at both ends comprises cable clips having a slotted aperture at both ends.",
    "5. The material testing system of claim 1 wherein the four retention springs are extension springs.",
    "6. The material testing system of claim 1 wherein the four retention springs are coil extension springs.",
    "7. The material testing system of claim 1 wherein each of the four or more cable clips is polymeric.",
    "8. The material testing system of claim 7 wherein the four or more cable clips are mutually identical in size.",
    "9. 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 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 bolt hole that intersects the 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.",
    "10. The method of claim 9, 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.",
    "11. The method of claim 9 wherein the step of engaging another end of the cable clip to a corresponding cable to maintain the cable in a noninterfering position comprises sliding the cable through a slot and into the aperture of the cable clip."
  ],
  "description_excerpt": "The invention described herein was made by employees of the United States Government and may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore.\n\nThe present disclosure generally relates to material testing using hydraulic grips, and more particularly to material testing systems having hydraulic wedge grips with retention springs.\n\nHydraulically actuated test frames are often used to evaluate the static and fatigue properties of materials. Two typical specimen retention methods are (1) pin-and-clevis and (2) hydraulic grips with wedges. An example of such material testing systems is MTS 810 material testing system by MTS Systems Corporation, Eden Prairie, Minn. When installing certain wedges used to grip test specimens with hydraulic grips on test machines, the cables used for installation must be left in place during subsequent testing. The cables are necessary for pulling the wedge retention springs up through the bottom of the wedge, via the wedge retention spring hole, where the end of the spring is retained by a wedge spring retention screw. The loose ends of these cables, if not restrained in some manner, can interfere with access to the test specimen and even cause minor injuries to fingers and hands.\n\nThe present innovation overcomes the foregoing problems and other shortcomings, drawbacks, and challenges of hydraulically gripping a test specimen during material testing.",
  "cpc": [
    "G01N 3/04",
    "G01N 2203/04",
    "G01N 2203/0411",
    "G01N 2203/0441",
    "G01N 2203/0447",
    "G01N 3/08",
    "G01N 3/10"
  ],
  "ipc": [
    "G01N 3/04",
    "G01N 3/08",
    "G01N 3/10"
  ],
  "assignees": [
    "United States Department of the Air Force"
  ],
  "inventors": [
    "James M Greer, Jr."
  ],
  "filing_date": "2022-10-28",
  "publication_date": "2025-02-04",
  "grant_date": "2025-02-04",
  "priority_date": "2020-09-17",
  "application_number": "US-202217975846-A",
  "family_id": "80626473",
  "cited_by_count": 2,
  "citations": [
    "US5021612A",
    "US5512727A",
    "US7739919B2"
  ]
}