BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention relate generally to methods and systems for structural health monitoring. More particularly, embodiments of the invention relate to methods and systems that can indicate the strain on a beam, regardless of the variable load, thereby more accurately measuring the structural health of the beam.

2. Description of Prior Art and Related Information

The following background information may present examples of specific aspects of the prior art (e.g., without limitation, approaches, facts, or common wisdom) that, while expected to be helpful to further educate the reader as to additional aspects of the prior art, is not to be construed as limiting the present invention, or any embodiments thereof, to anything stated or implied therein or inferred thereupon.

There are 600,000 bridges in the US. It is reported that 47,000 of these bridges are structurally deficient. These bridges are inspected manually every two years costing millions of dollars for inherently inaccurate manually taken data and leaving two years for the structural health of the structure to change for the worse without detection. Strain gauges have been used to measure the strain in beams for decades. Aircraft wings and industrial cranes receive an annual inspection for structural integrity and buildings are inspected after major earthquakes.

Strain gauges heretofore have measured the strain on the beam as well as the strain produced by the load. The instant invention indicates the strain on the beam regardless of the variable load thereby more accurately measuring the structural health of the beam.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a structural health sensor comprising a central strain gauge; at least one pair of strain gauges; and interface electronics operable to detect a change in resistance of the central strain gauge and each of the at least one pair of strain gauges, wherein each of the at least one pair of strain gauges disposed in a linear array with the central strain gauge; each of the at least one pair of strain gauges having a first strain gauge and a second strain gauge; and each of the first strain gauge and the second strain gauge of each of the at least one pair of strain gauges being spaced equidistant from the central strain gauge.

Embodiments of the present invention further provide a structural health sensor comprising a central strain gauge; at least two pair of strain gauges; and interface electronics operable to detect a change in resistance of the central strain gauge and each of the at least two pair of strain gauges, wherein each of the at least two pair of strain gauges disposed in a linear array with the central strain gauge; a first pair of the at least two pair of strain gauges having a first strain gauge and a second strain gauge; a second pair of the at least two pair of strain gauges having a third strain gauge and a fourth strain gauge; each of the first strain gauge and the second strain gauge being spaced equidistant a first distance from the central strain gauge; and each of the third strain gauge and the fourth strain gauge being spaced equidistant a second distance from the central strain gauge.

Embodiments of the present invention also provide a method for measuring a structural health of a device comprising disposing a central strain gauge on a neutral axis of the device; disposing at least one pair of strain gauges in a linear array with the central strain gauge; and electrically connecting the central strain gauge and the at least one pair of strain gauges to interface electronics operable to detect a change in resistance of the central strain gauge and each of the at least one pair of strain gauges, wherein each of the at least one pair of strain gauges having a first strain gauge and a second strain gauge; and each of the first strain gauge and the second strain gauge of each of the at least one pair of strain gauges being spaced equidistant from the central strain gauge.

An objective of the instant invention is to provide a sensor array that differentiates acceptable tensile and flexural stresses in a beam from stress patterns that indicate a fracture in the beam. Monitoring the safety of bridges, airplanes, cranes and building structures with instrumentation and in real time is more accurate, timely and less costly than manual inspection.

Embodiments of the present invention requires at least three strain gauges. Additional pairs of strain gauges can be added for redundancy in case of strain gauge failure. The single strain gauge is adhered to the beam directly over and with the sensing elements parallel to the neutral axis of the beam. The pairs of strain gauges are adhered to the beam parallel to the sensing elements of the single strain gauge on opposite sides and equidistant from the neutral axis. The single strain gauge senses the tensile stress in the beam.

The pairs of gauges sense the bending strain in the beam. A difference in the sum of the strains measured by each of the pair of strain gauges indicates a shift in the location of the neutral axis of the beam, indicating a potential structural health issue with the beam.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

