Computer program for calculating fastener forces
First Claim
1. A computer system for determining forces acting on fasteners forming a joint in a structural system having a grid point included in one of a plurality of structural members, wherein each of the members contributes to a global force and a global moment acting at the grid point, the computer system comprising:
- global means for determining said global force and said global moment, with said global force and said global moment being defined in a global coordinate system having an origin at the grid point;
means for transforming said global force and said global moment into a local force and a local moment defined by a local coordinate system;
means for translating said local force and said local moment from the grid point to a pattern centroid located at the joint;
nominal means for calculating a nominal axial force and a nominal shear force acting on each of the fasteners for a nominal case wherein all of the fasteners are operative;
fail-safe means for calculating fail-safe forces acting axially on each of the fasteners for fail-safe cases wherein each of the fasteners, one at a time, is assumed to transfer an axial force equal to zero, and said fail-safe force comprises a resultant axial force on each of the fasteners remaining operative; and
announcing means for announcing characteristics of suitable fasteners, the characteristics comprising the nominal axial forces and nominal shear forces that the fasteners can withstand without failure.
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Accused Products
Abstract
A NASTRAN-programmed computer calculates force and moment data for a structure including joints of interest. The NASTRAN data is read by a computer programmed with the invented program. For each joint, the user selects the members which contribute forces to the joint, and also selects the nearest grid point. A computer programmed with the invented program calculates the resultant force and moment at the proximate grid point. The force and moment are originally defined in a global coordinate system, subsequently transformed into a local coordinate system, and then translated to the centroid of the joint'"'"'s fastener pattern. Axial and shear forces for each fastener are calculated for the nominal case wherein all of the fasteners are operative. Furthermore, each fastener, in turn, is assumed not to transmit axial force and the resulting fail-safe axial forces respectively acting on the remaining operative fasteners are calculated. Fastener forces are screened to determine the critical nominal axial and shear forces, and the critical fasteners which transmit the foregoing critical forces; in addition to the critical fail-safe axial force and consonant critical fail-safe fastener.
56 Citations
26 Claims
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1. A computer system for determining forces acting on fasteners forming a joint in a structural system having a grid point included in one of a plurality of structural members, wherein each of the members contributes to a global force and a global moment acting at the grid point, the computer system comprising:
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global means for determining said global force and said global moment, with said global force and said global moment being defined in a global coordinate system having an origin at the grid point; means for transforming said global force and said global moment into a local force and a local moment defined by a local coordinate system; means for translating said local force and said local moment from the grid point to a pattern centroid located at the joint; nominal means for calculating a nominal axial force and a nominal shear force acting on each of the fasteners for a nominal case wherein all of the fasteners are operative; fail-safe means for calculating fail-safe forces acting axially on each of the fasteners for fail-safe cases wherein each of the fasteners, one at a time, is assumed to transfer an axial force equal to zero, and said fail-safe force comprises a resultant axial force on each of the fasteners remaining operative; and announcing means for announcing characteristics of suitable fasteners, the characteristics comprising the nominal axial forces and nominal shear forces that the fasteners can withstand without failure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer program for determining forces acting on fasteners forming a joint in a structural system having a grid point included in one of a plurality of structural members, wherein each of the structural members contributes to a global force and a global moment acting at the grid point, the computer program containing program instructions for:
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determining said global force and said global moment, with said global force and said global moment bring defined in a global coordinate system having an origin at the grid point; transforming said global force and said global moment into a local force and a local moment defined by a local coordinate system; translating said local force and said local moment from the grid point to a pattern centroid located at the joint; calculating a nominal axial force and a nominal shear force acting on each of the fasteners for a nominal case wherein all of the fasteners are operative; calculating fail-safe forces acting axially on each of the fasteners for each of a plurality of fail-safe cases in which a different one of the fasteners is assumed to be inoperative and therefore to transfer an axial force equal to zero, wherein, for each of said fail-safe cases, said fail-safe force comprises a resultant axial force on each of the fasteners remaining operative; and directing the computer systems to announce characteristics of suitable fasteners, the characteristics comprising the nominal axial forces and nominal shear forces that the fasteners can withstand without failure. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 25, 26)
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17. A computer system for determining forces acting on fasteners forming a joint in a structural system having a grid point included in one of a plurality of structural members, wherein each of the structural members contributes to a global force and a global moment acting at the grid point, the computer system comprising:
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a memory; a processor; and a computer program stored in said memory, wherein said processor is responsive to instructions contained in said computer program for; determining said global force and said global moment, with said global force and said global moment being defined in a global coordinate system having an origin at the grid point; transforming said global force and said global moment into a local force and a local moment defined by a local coordinate system; translating said local force and said local moment from the grid point to a pattern centroid located at the joint; calculating a nominal shear force and a nominal shear force acting on each of the fasteners for a nominal case wherein all of the fasteners are operative; calculating fail-safe forces acting axially on each of the fasteners for each of a plurality of fail-safe cases in which a different one of the fasteners is assumed to be inoperative and therefore to transfer an axial force equal to zero, wherein, for each of said fail-safe cases, said fail-safe force comprises a resultant axial force on each of the fasteners remaining operative; and directing the computer system to announce characteristics of suitable fasteners, the characteristics comprising the nominal axial forces and nominal shear forces that the fasteners can withstand without failure. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification