Method for preventing or arresting crack development and propagation
AssigneeSurface Technology Holdings, Ltd.
InventorPaul S. Prevey, III
Life of this patent
Estimating the term…
Abstract
A method for preventing or arresting the development and propagation of cracks in the material surrounding a fastener. The method includes introducing compressive residual stresses in the material surrounding the fastener. The compressive residual stresses offset the high residual tensile and applied stresses which the material may be subjected to in operation and thereby prevent or arrest the development of cracks. Using the output of a sensor, the surface treatment apparatus is positioned relative to a fastener. A compression tool is impinged against the surface of the material adjacent to the fastener and rotated around the perimeter of the fastener thereby inducing a zone of compressive residual stress.
Claims16
A method for preventing or arresting crack development and propagation in material surrounding a fastener installed along and extending through the surface of a structure or article, the method comprising the steps of:
- locating a position of a fastener fully installed in the surface of the structure;
- positioning an apparatus for inducing residual compressive stress relative to the fastener;
- and
- rotating the apparatus around the fastener to induce compressive residual stress in at least a portion of the material circumscribing a portion of the fastener such that said compressive residual stress extends circumferentially around the fastener from the surface to a predetermined depth and further compresses the material inwardly towards the fastener.
A method for inducing compressive residual stress in a surface of a workpiece surrounding a portion of a fastener that is installed in a structure or article to prevent or arrest crack development and propagation, the method comprising the steps of:
- locating a fastener and positioning an apparatus in position relative to the fastener;
- using an apparatus having a rotational actuator and a tool, holder for receiving and positioning attachments relative to an axis of rotation of the tool holder;
- and
- using a compression tool adjustably positioned on the tool holder such that the compression tool impinges and is rotated around the surface surrounding a portion of the fastener to induce residual compressive stress in the surface such that the compressive residual stress extends circumferentially around the fastener from the surface to a predetermined depth and further compresses the material inwardly towards the fastener.
A method for inducing compressive residual stress in the material surrounding a portion of a fastener installed in a structure or article to prevent or arrest crack development and propagation, the method comprising the steps of:
- rotating at least one compression tool circumferentially around a portion of the fastener to induce compressive residual stress in the material surrounding the fastener such that the compressive residual stress extends circumferentially around the fastener from the surface to a predetermined depth and such that the material surrounding the portion of the fastener is compressed inwardly towards the fastener;
- using a positioning device to position the compression tool relative to the fastener;
- and
- using at least one sensor for locating the fastener, the at least one sensor operatively connected to the compression tool.
Dependencies are inferred from the claim text.