Strain indicator using an optical indicator means
First Claim
1. A strain indicator for incorporation between a first abutment means and a second abutment means to indicate variations in the mutual separation of said first and said second abutment means, said strain indicator comprising an elongate member having opposite ends adapted to be lodged respectively against said first and second abutment means, said elongate member being deformable in a substantially elastic manner by longitudinal compression applied between said opposite ends, at least part of said elongate member being free to move transversely within said strain indicator, said deformation of said elongate member by said longitudinal compression causing a variation in the curvature thereof between said opposite ends, said elongate member carrying optical indicator means which vary in position substantially in accordance with the variation of said curvature of said elongate member whereby variations in the position of said optical indicator means during use of said strain indicator optically indicate variations in the curvature of said elongate member consequent upon variations in the longitudinal compression thereof induced by variations in said mutual separation of said first and second abutment means.
4 Assignments
0 Petitions
Accused Products
Abstract
A strain indicator of the type wherein a change in length of the strain indicator gives a visual indication of the change in length. The strain indicator has an elongate strip supported at either end such that the curvature of the strip changes with changes in strain. An optical indicator such as a reflector is mounted on the strip so that the change in curvature can be measured.
15 Citations
25 Claims
- 1. A strain indicator for incorporation between a first abutment means and a second abutment means to indicate variations in the mutual separation of said first and said second abutment means, said strain indicator comprising an elongate member having opposite ends adapted to be lodged respectively against said first and second abutment means, said elongate member being deformable in a substantially elastic manner by longitudinal compression applied between said opposite ends, at least part of said elongate member being free to move transversely within said strain indicator, said deformation of said elongate member by said longitudinal compression causing a variation in the curvature thereof between said opposite ends, said elongate member carrying optical indicator means which vary in position substantially in accordance with the variation of said curvature of said elongate member whereby variations in the position of said optical indicator means during use of said strain indicator optically indicate variations in the curvature of said elongate member consequent upon variations in the longitudinal compression thereof induced by variations in said mutual separation of said first and second abutment means.
- 10. An assembly of an article and a strain indicator, said article comprising a first abutment means and a second abutment means which are mutually spaced apart on said article in a direction thereon which includes at least a component of a load to which the article is subjected in use thereof, which said load strains said article and induces variations in the mutual separation of said first and second abutment means in dependence upon the magnitude of the component of said load acting in said direction, said strain indicator comprising an elongate member and optical indicator means carried thereby, at least part of said elongate member being free to move transversely within said strain indicator, said elongate member having the opposite ends thereof lodged respectively against said first and second abutment means in a manner inducing a longitudinal precompression in said elongate member and a corresponding pre-curvature of said elongate member, whereby an increase in tension or a decrease in compression exerted by said component of said load on said article increases the mutual separation of said first and second abutment means and correspondingly decreases the curvature of said elongate member to cause said optical indicator means optically to indicate such decrease in curvature of said elongate member, and a decrease in tension or an increase in compression exerted by said component of said load on said article decreases the mutual separation of said first and second abutment means and correspondingly increases the curvature of said elongate member to cause said optical indicator means optically to indicate such increase in curvature of said elongate member.
Specification