Patent ID: 6904395

Claim:
A system of generating a finite element mesh for a threaded fastener and joining structure assembly comprising: a computer system, wherein said computer system includes a memory, a processor, an input device and a display device; a mesh model of the threaded fastener and joining structure assembly generated on the computer system wherein nodes and elements for each non-threaded portion of the threaded fastener and joining structure assembly are created using cylindrical coordinates and nodes and elements for each threaded portion of the threaded fastener and joining structure assembly are created using helical coordinates; a mesh generated for a fastener joining together a clearance hole block and a threaded block, wherein said mesh of the fastener includes nodes created in radial, tangential and vertical directions for each non-threaded portion of the fastener using cylindrical coordinates and elements defined by interconnecting the nodes, nodes created for each transition portion of the fastener transitioning between the non-threaded portion of the fastener and a threaded portion of the fastener by stretching a hexahedral element in a vertical direction while sweeping about a vertical axis, and elements defined by interconnecting the nodes and interleaving wedge elements at the end of a revolution, a mesh of the fastener thread generated using helical coordinates, and nodes for each transition portion of the fastener transitioning between the fastener threads and a non-threaded portion of the fastener created by shrinking a hexahedral element in a vertical direction while sweeping about a vertical axis, and elements defined by interconnecting the nodes and interleaving wedge elements at the end of a revolution; and wherein a mesh of the fastener threads includes: a mesh of a first thread of the fastener threads, wherein nodes are created using gradual stretching on a helix by moving nodes upwards to helical coordinates while sweeping about a vertical axis, and elements defined by interconnecting the nodes; a mesh of a thread body of the fastener threads, wherein nodes are created using constant stretching on a helix by moving nodes upwards to helical coordinates while sweeping about a vertical axis, and elements defined by interconnecting the nodes; and a mesh of a last thread of the fastener threads, wherein nodes are created using gradual shrinking on a helix by moving nodes downward to cylindrical coordinates while sweeping about a vertical axis, and elements are defined by interconnecting the nodes.