For measuring the stress history in a simple form, which is widely applicable to various types of structural materials which the elastic modulus is different from each other, a large number of calcite particles is embedded as a stress sensor in a cement-based composite material that can be elastically deformed after receiving an external.

A twin-crystal density of the calcite particles is measured after an external force is applied to the composite material, to convert the twin-crystal density to a strain by an approximate formula set in terms of a strain ε (%) generated in the composite material and a twin-crystal density Dtw (lines/mm) of the calcite particles, and further to convert this strain to a stress by the elastic modulus of the composite material, whereby to estimate the history of stress and strain. The approximate formula between strain and twin-crystal density is independent of the modulus of the composite material and is used in a common form.

For measuring the stress history in a simple form, which is widely applicable to various types of structural materials which the elastic modulus is different from each other, a large number of calcite particles is embedded as a stress sensor in a cement-based composite material that can be elastically deformed after receiving an external.

A twin-crystal density of the calcite particles is measured after an external force is applied to the composite material, to convert the twin-crystal density to a strain by an approximate formula set in terms of a strain ε (%) generated in the composite material and a twin-crystal density Dtw (lines/mm) of the calcite particles, and further to convert this strain to a stress by the elastic modulus of the composite material, whereby to estimate the history of stress and strain. The approximate formula between strain and twin-crystal density is independent of the modulus of the composite material and is used in a common form.

A vehicle seat assembly including a seat frame assembly including a seat base and a seat back pivotally connected to the seat base. The seat back includes at least one resin fuse arranged in the seat back to indicate structural loading in the vehicle seat assembly above a tolerance loading. The at least one resin fuse includes an aperture extending through the seat back and comprising a flange encircling the aperture and extending generally perpendicular to the seat back, and an indicator bar extending across a diameter of the aperture. The aperture is open on either side of the indicator bar.

A vehicle seat assembly including a seat frame assembly including a seat base and a seat back pivotally connected to the seat base. The seat back includes at least one resin fuse arranged in the seat back to indicate structural loading in the vehicle seat assembly above a tolerance loading. The at least one resin fuse includes an aperture extending through the seat back and comprising a flange encircling the aperture and extending generally perpendicular to the seat back, and an indicator bar extending across a diameter of the aperture. The aperture is open on either side of the indicator bar.

A transducer for assisting in measuring displacement or strain in an object of interest is described. A plate has at least two end sections for mounting the transducer. It comprises a flexible connection between the two end sections. The flexible connection comprises a plurality of rigid portions and flexible interconnections between the rigid portions for allowing relative movement of the rigid portions with respect to each other. The flexible connection has a central section substantially having a U-shape comprising two rigid portions spaced from each other over a distance and adapted for positioning a strain sensing element at the spacing in between said two rigid portions. The rigid portions and flexible interconnections are arranged so that a displacement applied to the end sections results in a relative displacement at the spacing in the central section that is larger than the relative displacement applied to the end sections.

A transducer for assisting in measuring displacement or strain in an object of interest is described. A plate has at least two end sections for mounting the transducer. It comprises a flexible connection between the two end sections. The flexible connection comprises a plurality of rigid portions and flexible interconnections between the rigid portions for allowing relative movement of the rigid portions with respect to each other. The flexible connection has a central section substantially having a U-shape comprising two rigid portions spaced from each other over a distance and adapted for positioning a strain sensing element at the spacing in between said two rigid portions. The rigid portions and flexible interconnections are arranged so that a displacement applied to the end sections results in a relative displacement at the spacing in the central section that is larger than the relative displacement applied to the end sections.

A method and system method for estimating fatigue damage in a structure obtains fatigue damage data collected using at least one sensor associated with the structure during at least one test operation and also obtains structure use parameter data collected during the at least one test operation. The obtained fatigue data and the obtained use parameter data are used to compute coefficients of at least one generic polynomial function that outputs a fatigue damage value based on inputs representing use parameter data. The at least one generic polynomial function is used to output an estimated fatigue damage value based on inputs representing use parameter data collected during use of the structure.

A method and system method for estimating fatigue damage in a structure obtains fatigue damage data collected using at least one sensor associated with the structure during at least one test operation and also obtains structure use parameter data collected during the at least one test operation. The obtained fatigue data and the obtained use parameter data are used to compute coefficients of at least one generic polynomial function that outputs a fatigue damage value based on inputs representing use parameter data. The at least one generic polynomial function is used to output an estimated fatigue damage value based on inputs representing use parameter data collected during use of the structure.

In one general aspect, a composite foam comprises a non-layered mixture of a polymeric foam with a plurality of voids; and a plurality of conductive fillers disposed in the polymeric foam. The conductive fillers are disposed in an even manner from outer surface to outer surface. In some implementations, the conductive fillers are up to 25% by weight of the composite foam. In some implementations, the composite foam may be used as padding. In some implementations, the composite foam may be used as a strain gauge. In some implementations, the foam may be in contact with a voltage detector.

In one general aspect, a composite foam comprises a non-layered mixture of a polymeric foam with a plurality of voids; and a plurality of conductive fillers disposed in the polymeric foam. The conductive fillers are disposed in an even manner from outer surface to outer surface. In some implementations, the conductive fillers are up to 25% by weight of the composite foam. In some implementations, the composite foam may be used as padding. In some implementations, the composite foam may be used as a strain gauge. In some implementations, the foam may be in contact with a voltage detector.