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US 4,304,135 AGranted
Constraint factor for structural monitoring
AssigneeConoco Inc.
InventorsMarvin L. Peterson, Norman W. Hein, Jr., Donald H. Oertle, Steven E. Hawkins
Life of this patent
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Abstract
A dual element strain gauge is placed near a welded or otherwise constrained joint on a structural member so as to provide a constraint factor. The location for the strain gauge must be selected to provide constraint factor that is preferably near either maximum or minimum value. The strain gauge is monitored to detect a change in the initial constraint factor, which indicates failure has begun or is imminent.
Claims18
A method for predicting structural failure and detecting axial failure in constrained structural members subject to fatigue and static stress comprising
- (a) placing at least one dual element strain gauge near a structural constraint, said strain gauge having one element extending substantially parallel to the longitudinal axis of the structural member to record longitudinal strain, and the second element extending substantially perpendicular to said first element to record transverse strain, wherein said placement is determined by a maximum or minimum reading from either element of said gauge;
- (b) calculating a constraint factor of said structural member by determining the ratio of longitudinal strain to transverse strain, then
- (c) monitoring said factor for change, said change indicating structural failure.
Dependencies are inferred from the claim text.