Abstract: In accordance with the present invention, a photoelastic layer and a monitoring device with an integrated polarizer for detecting stress and strain is described. Stresses and strains in the photoelastic layer or in the photoelastic monitoring device can be detected using photoelastic methods. The integrated polarizer allows photoelastic inspections to be carried out with non-polarized incident light, thereby reducing inspection costs and time associated with photoelastic analysis. Also in accordance with the present invention, a method is described for photoelastic analysis comprising a photoelastic coating and an integrated polarizer. The integrated polarizer allows for photoelastic analysis using a regular non-polarized light source. Stresses and strains in the photoelastic coating and in the underlying material can be detected easily and quickly.

Abstract: The present invention provides a monitoring device for detecting stresses and strains in structural components and a method of using the monitoring device. The monitoring device comprises a base material, one or more attachment points for attaching the monitoring device to a structure to be monitored, a detection zone on the monitoring device, and a means for detecting the presence of stress and strain in the detection zone. The dimensions and material of the monitoring device are chosen such that a predetermined level of strain transmitted to the monitoring device from the structure will result in a known level of stress and strain in the detection zone. Detection of stress and strain in the detection zone can be correlated to a level of stress and strain experienced by the structure at the point of attachment of the monitoring device.

Abstract: A photoelastic coating for structural monitoring of bridges, buildings, and other structures comprises an optically translucent or transparent photoelastic layer. The photoelastic coating is applied to the structure as a solvent-based liquid or gel. The photoelastic properties of the photoelastic layer are used to detect stress and strain or plastic deformation in the structure using photoelastic techniques. Also described is a method of structural monitoring comprising applying a photoelastic coating to a structure as a solvent-based liquid or gel. Presence of fringe patterns in the reflected light from the photoelastic layer indicates the presence of stress and strain in the photoelastic layer. Stress and strain in the photoelastic layer indicates stress and strain or plastic deformation in the underlying structure. The invention can be used for detecting when structures have been overloaded or when stress limits have been exceeded.

Abstract: A valve includes a housing with an elongated bore having a longitudinal axis and a spool reciprocatingly mounted within the bore for relative movement along the bore parallel to the axis. The housing has a housing passageway and the spool has a spool passageway. The passageways align in at least one axial position of the spool along the bore, whereby fluids can pass between the spool and the housing. The passageway of one of the spool or the housing includes a first groove which extends parallel to the axis, but not substantially about said one of the spool or the housing. The passageway of another of the spool or the housing includes a second groove which extends circumferentially about said another of the spool or the housing.

Abstract: A method of detecting stress and strain using a powder coat finish and photoelastic techniques. A part is provided with a photoelastic layer comprising a non-opaque powder coat finish that becomes optically anisotropic when stressed. Photoelastic techniques are used to detect and measure stress and strain in the part. Fringe patterns appear in the photoelastic layer indicating the locations and magnitudes of the stress and strain when the part is illuminated with polarized light and viewed through a polarizing filter. Stress and strain resulting from applied forces are detected. Structural deformation in parts that have experienced plastic deformation is also detected. Photoelastic techniques using powder coat as a photoelastic technique are less expensive and easier to apply than traditional photoelastic coatings. Applications include testing of prototypes, stress testing, inspection and monitoring of production parts, and anywhere that viewing and measuring of stress and strain are of interest.

Abstract: A method of detecting stress and strain using a powder coat finish and photoelastic techniques. A part is provided with a photoelastic layer comprising a non-opaque powder coat finish that becomes optically anisotropic when stressed. Photoelastic techniques are used to detect and measure stress and strain in the part. Fringe patterns appear in the photoelastic layer indicating the locations and magnitudes of the stress and strain when the part is illuminated with polarized light and viewed through a polarizing filter. Stress and strain resulting from applied forces are detected. Structural deformation in parts that have experienced plastic deformation is also detected. Photoelastic techniques using powder coat as a photoelastic technique are less expensive and easier to apply than traditional photoelastic coatings. Applications include testing of prototypes, stress testing, inspection and monitoring of production parts, and anywhere that viewing and measuring of stress and strain are of interest.