Load measurement apparatus including miniature instrumented hydrostatic cell

A load measurement apparatus for measuring the load exerted on a structural member, said apparatus comprising:

• a miniature instrumented hydrostatic cell including;
• a housing;
• a closed chamber defined in said housing;
• a membrane that forms one wall of said chamber, the rigidity of said membrane being substantially less than that of said housing;
• a temperature compensation insert disposed in said chamber;
• an incompressible fluid completely filling the portions of said chamber not occupied by said inert;
• and,
• pressure measurement means for providing measurements of the pressure within said chamber;
• a pressure arm having a disk-like configuration;
• first means for rigidly coupling a first end of said pressure arm to the structural member so that said pressure arm displaces as load is exerted on the structural member;
• and,
• second means for rigidly mounting said cell in proximity to said pressure arm so that said membrane engages the second end of said pressure arm and displaces as said pressure arm displaces.

A load measurement apparatus for measuring the load exerted on a structural member, said apparatus comprising:

• a miniature instrumented hydrostatic cell including:
• a housing consisting of a plate having opposing, substantially planar, first and second major surfaces;
• a closed chamber defined in said housing;
• a membrane that is integral with said plate and that forms one wall of said chamber, said membrane extending to said first major surface of said plate and having a rigidity that is substantially less than that of said plate;
• a temperature compensation insert disposed in said chamber;
• an incompressible fluid completely filling the portions of said chamber not occupied by said insert;
• and,
• pressure measurement means for providing measurements of the pressure within said chamber;
• a pressure arm;
• first means rigidly securing a first end of said pressure arm to the structural member so that said pressure arm displaces as load is exerted on the structural member;
• and,
• second means for rigidly mounting said cell in proximity to said pressure arm so that said membrane engages a second end of said pressure arm and displaces as said pressure arm displaces, said second means including:
• a bore extending through said plate from said first major surface to said second major surface;
• an adjustment screw passing through said bore and threadably received in the structural member;
• a first spring interposed between said adjustment screw and said second major surface of said plate;
• and,
• a second spring interposed between said first major surface of said plate and the structural member.

A miniature instrumented hydrostatic cell for use in measuring the load exerted on a structural member, said cell comprising:

• a housing that consists of a first cylindrical portion and a second cylindrical portion projecting from and integral with said first cylindrical portion, wherein said first and second cylindrical portions have a common longitudinal axis, and wherein the diameter of said first cylindrical portion is greater than that of said second cylindrical portion;
• a cavity defined in said housing;
• a membrane for receiving at least a portion of the load to be measured, said membrane forming a first wall of said cavity, said membrane being integral with said second cylindrical portion and forming a portion of an end face thereof, the rigidity of said membrane being substantially less than that of said housing;
• a temperature compensation insert disposed within said cavity;
• sealing means mounted in said housing and extending to a second wall of said cavity, for introducing an incompressible fluid into said cavity and for permitting said cavity to be substantially evacuated of air so that all portions of said cavity not occupied by said insert are completely filled with the incompressible fluid;
• and,
• pressure measurement means for providing measurements of the pressure within said cavity.

A load measurement apparatus for measuring the load exerted on a structural member, said apparatus comprising:

• a miniature instrumented hydrostatic cell including:
• a housing;
• a closed chamber defined in said housing;
• a membrane for receiving at least a portion of the load to be measured, such membrane forming one wall of said chamber, the rigidity of said membrane being substantially less than that of said housing;
• a temperature compensation insert disposed in said chamber;
• an incompressible fluid completely filling the portions of said chamber not occupied by said insert;
• and,
• pressure measurement means for providing measurements of the pressure within said chamber;
• a pressure arm;
• first means for rigidly coupling a first end of said pressure arm to the structural member so that said pressure arm displaces as load is exerted on the structural member;
• and,
• second means for ridigly mounting said cell in proximity to said pressure arm so that said membrane engages a second end of said pressure arm and displaces as said pressure arm displaces, said second means mounting said cell for translative movement to and from said pressure arm, and including adjustment means bearing on said housing for selectively adjusting the position of said cell relative to said pressure arm upon the absence of load exerted on the structural member so as to cause a pre-load displacement of said membrane and a consequent pre-load pressure in said chamber, said adjustment means including a spring bearing on said housing and means for selectively compressing said spring against said housing, the rigidity of said spring being greater than that of said membrane but substantially less than that of said housing.

A miniature instrumented hydrostatic cell for use in measuring the load exerted on a structural member, said cell comprising:

• a housing that consists of a plate having opposing, substantially planar, first and second major surfaces;
• a cavity defined in said housing;
• a membrane for receiving at least a portion of the load to be measured, said membrane forming a first wall of said cavity, said membrane being integral with said plate and forming a portion of said first major surface thereof, the rigidity of said membrane being substantially less than that of said housing;
• a temperature compensation insert disposed within said cavity;
• sealing means mounted in said housing and extending to a second wall of said cavity, for introducing an incompressible fluid into said cavity and for permitting said cavity to be substantially evacuated of air so that all portions of said cavity not occupied by said insert are completely filled with the incompressible fluid;
• and,
• pressure measurement means for providing measurements of the pressure within said cavity.