Method for evaluating measured values for identifying a material fatigue
First Claim
1. A method for evaluation of measured values for the recognition of defect conditions due to material fatigue on aircraft parts, in which strain sensors (6) are applied on the critical locations of an aircraft (1) or its parts, whereby the measured values of the strain sensors are detected at different loading conditions through several measuring circuits, are amplified, and are stored, and from which an evaluating apparatus (9) derives, signals or indicates a material fatigue through comparison of current measured values with previous measured values, characterized in that the critical aircraft parts (1) are impinged on with a plurality of prescribed loading conditions by a plurality of externally acting loading elements (3), and in that the strain effect caused thereby is detected through a plurality of measuring circuits including strain gages as the strain sensors, and the evaluating apparatus (9) for at least each loading condition and each measuring circuit forms an allocated reference value and a permissible limit value range, whereby, according to the detected strain measured values (XM) for each loading condition, from at least the first existing current measured values for each measuring circuit these are evaluated as reference values (XR) and therefrom an absolute limit value range is calculated for each reference value (XR) through prescription of a permissible deviation (nGW %), which limit value range is subsequently coupled with the current measured values so that the exceeding of the limit value range by at least one current measured value represents occurrence of a material fatigue manifestation.
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Accused Products
Abstract
In a method of evaluating measured values for recognizing defect conditions due to material fatigue on aircraft parts, strain sensors (6) are applied on the critical locations of an aircraft (1) and measured values of outputs of the strain sensors are detected at different loading conditions, amplified and stored through several measuring circuits. An evaluating apparatus (9) derives, signals or indicates a material fatigue by comparison of current measured values with previous measured values. The critical aircraft parts (1) are impinged on with prescribed loading conditions by loading elements (3). The strain effect caused thereby is detected by measuring circuits. The evaluating apparatus (9) forms, for at least each loading condition and each measuring circuit, an allocated reference value and a permissible limit value range. If current measured values exceed the limit value range, this represents a material fatigue manifestation.
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Citations
15 Claims
- 1. A method for evaluation of measured values for the recognition of defect conditions due to material fatigue on aircraft parts, in which strain sensors (6) are applied on the critical locations of an aircraft (1) or its parts, whereby the measured values of the strain sensors are detected at different loading conditions through several measuring circuits, are amplified, and are stored, and from which an evaluating apparatus (9) derives, signals or indicates a material fatigue through comparison of current measured values with previous measured values, characterized in that the critical aircraft parts (1) are impinged on with a plurality of prescribed loading conditions by a plurality of externally acting loading elements (3), and in that the strain effect caused thereby is detected through a plurality of measuring circuits including strain gages as the strain sensors, and the evaluating apparatus (9) for at least each loading condition and each measuring circuit forms an allocated reference value and a permissible limit value range, whereby, according to the detected strain measured values (XM) for each loading condition, from at least the first existing current measured values for each measuring circuit these are evaluated as reference values (XR) and therefrom an absolute limit value range is calculated for each reference value (XR) through prescription of a permissible deviation (nGW %), which limit value range is subsequently coupled with the current measured values so that the exceeding of the limit value range by at least one current measured value represents occurrence of a material fatigue manifestation.
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15. A method of determining an occurrence of a material fatigue manifestation in at least one of plural aircraft components of an aircraft due to material fatigue during fatigue testing of said aircraft components, comprising the steps:
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a) by externally acting on said aircraft with a plurality of externally acting loading elements, imposing on said aircraft components a plurality of prescribed loading conditions in successive loading cycles, thereby causing strains in said aircraft components; b) detecting said strains with strain gages arranged on said aircraft components, and with said strain gages producing strain gage outputs representative of said strains; c) evaluating said strain gage outputs to determine therefrom measured strain values respectively successively in said successive loading cycles and respectively allocated to said strain gages; d) for each one of said loading conditions for each one of said strain gages, respectively establishing a reference value based on at least a first one of said measured strain values arising in a first one of said successive loading cycles; e) specifying a permissible deviation; f) for each said reference value, determining an absolute limit value range based on said permissible deviation relative to said reference value; g) comparing said measured strain values to said absolute limit value range, respectively for each one of said loading conditions for each one of said strain gages; and h) if said comparing in said step g) determines that at least one of said measured strain values falls outside of said absolute limit value range, then in response thereto determining, signaling or indicating that a material fatigue manifestation has occurred in at least one of said aircraft components.
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Specification