Abstract: A binary code symbol for non-linear strain measurement designed specifically for perimeter-based deformation and strain analysis. The symbol is rectangular with a continuous outer perimeter, two data regions along adjacent sides of the rectangle and a utility region adjacent each side opposite the data regions. Each data region is made up of a number of data cells, and each utility region is made up of utility cells with alternating appearance. The inner half of the utility regions can be used to store auxiliary information and/or codes. There are two distinct finder cells on opposite corners of the rectangle, which can be used to orient the symbol. A non-linear strain gage for measuring the strain on an object under load in accordance includes a target, a sensor, and a computer, wherein the target is a binary code symbol.

Abstract: An optical linear strain gage includes a target, a sensor, and a computer, wherein the target contains a gage length defined by end points. The target can be a one-dimensional barcode, the gage length defined between, and perpendicular to, two chosen parallel lines of the barcode. The target, including a gage length, is associated with an object such that deformation of the gage length and deformation of the object are the same; target can emit or reflect a detectable physical quantity. The sensor is compatible with and pre-processes the physical quantity from the target and provides data to the computer. The computer analyzes the data output and calculates the strain directly on the body based on the pre-processed and analyzed data. Measuring strain on an object using the strain gage includes identifying the changes in the gage length as a function of time and load applied and calculating strain.

Abstract: Machine vision is used to track nodes on the perimeter of a geometric shape associated with a body undergoing cyclic loading, the geometric shape defining a target. The movement of the nodes is related to calculate strain through principles of Finite Element Analysis. The calculated strain is used to determine fatigue damage in the body based on an equation and data obtained using strain-controlled test methods.

Abstract: An apparatus and method of measuring and analyzing the deformation of deformable bodies which includes a source of an electromagnetic or accoustical signal emitted from a deformable body which can be received and analyzed so that the signal can be analyzed when the body is in a reference state with the signal being subsequently analyzed when the body is undergoing or has undergone deformation with the reference state signal and deformation state signal being compared and analyzed to provide significant information with respect to various characteristics of the body.

Abstract: A method and apparatus for measuring stress and strain associated with a pipe, pressurized vessel, structural member or deformable body containing a flaw or stress concentration utilizes a laser beam to illuminate a surface being analyzed and an optical data digitizer to sense a signal provided by the light beam reflected from the illuminated surface. One signal is received from the surface in a reference condition and subsequent signals are received from the surface after surface deformation. The optical data digitizer provides the received signal to an image processor, and the processor stores the signals and correlates the deformed image received with the reference image and then sends this correlated information to a minicomputer which performs mathematical analyses of the signal to determine stress and strain associated with the surface. The apparatus is constructed as one integral unit, and further includes a digital and tape display, as well as a television monitor and an electro-optic range indicator.