Jentek Sensors, Incorporated

David C Grundy

Neil J Goldfine

Andrew P Washabaugh

Darrell E Schlicker

Vladimir A Zilberstein

Ian C Shay

Robert J Lyons

Yanko K Sheiretov

Vladimir B Tsukernik

Mark D Windoloski

Karen E Walrath

Volker Weiss

Christopher A Craven

Scott A Denenberg

Todd M Dunford

David A Jablonski

Floyd W Spencer

Christopher Root

J Timothy Lovett

Leandro M Lorilla

James M Fisher

Ian C Shav

Methods and apparatus for enhancing performance curve generation, damage monitoring, and improving non-destructive testing performance. Damage standards used for performance curve generation are monitored using a non-destructive testing (NDT) sensor during a damage evolution test performed with the standard. The evolution test may be intermittently paused to permit ground truth data to be collected in addition to the NDT sensor data. A damage evolution model may be used to estimate ground truth data during the intervening periods of the damage evolution test. The NDT sensor data and ground truth data are used to generate performance curves for the NDT system. Multiple sensors may be monitored at multiple locations on the damage standard and multiple damage evolution tests may be performed with multiple damage standards.

Performance curve generation for non-destructive testing sensors

A substantially planar eddy-current sensor having durability enhancing pillars in an active region is provided. The pillars are distributed and sized so as to have limited effect on the sensor's performance. When the sensor is mounted on a component such that the sensor experiences forces on a top and bottom surface, the pillars bear the load reducing the load bore by the active elements (e.g., drive winding, sense elements). A sensor with redundant drive windings and/or redundant sense elements is disclosed. The redundant elements may be connected to separate electronics. Another aspect relates to providing a reference transformer for calibration of a sensor. The secondary windings of the reference transformer are connected in series with the sense elements of the sensor to be calibrated. Transimpedance measurements are made when the drive winding of the reference transformer is excited. The measurements are used to correct transimpedance measurements made when the drive winding of the sensor is excited. A system having an impedance analyzer and a plurality of multiplexing units is disclosed for monitoring a plurality of sensor. Each multiplexing units directs an excitation signal to the drive winding of a respective sensor and returns, serially, the sense element responses back to the impedance analyzer. The system coordinates the excitation of each sensor and return of the sensor response to share a serial network. The multiplexing units may have a reference transformer for calibration of their respective sensors. Optical communication may be used.

Durability enhanced and redundant embedded sensors

The condition of internal or hidden material layers or interfaces is monitored and used for control of a process that changes a condition of a material system. The material system has multiple component materials, such as layers or embedded constituents, or can be represented with multiple layers to model spatial distributions in the material properties. The material condition changes as a result of a process performed on the material, such as by cold working, or from functional operation. Sensors placed proximate to the test material surface or embedded between material layers are used to monitor a material property using magnetic, electric, or thermal interrogation fields. The sensor responses are converted into states of the material condition, such as temperature or residual stress, typically with a precomputed database of sensor responses. The sensor responses can also be used to determine properties of the test material, such as electrical conductivity or magnetic permeability, prior to conversion to the material state. The states are used to support control decisions that control the process or operation causing the material condition to change.

Internal material condition monitoring for control

A framework for adaptively managing the life of components. A sensor provides non-destructive test data obtained from inspecting a component. The inspection data may be filtered using reference signatures and by subtracting a baseline. The filtered inspection data and other inspection data for the component is analyzed to locate flaws and estimate the current condition of the component. The current condition may then be used to predict the component's condition at a future time or to predict a future time at which the component's condition will have deteriorated to a certain level. A current condition may be input to a precomputed database to look up the future condition or time. The future condition or time is described by a probability distribution which may be used to assess the risk of component failure. The assessed risk may be used to determine whether the part should continue in service, be replaced or repaired. A hyperlattice database is used with a rapid searching method to estimate at least one material condition and one usage parameter, such as stress level for the component. The hyperlattice is also used to rapidly predict future condition, associated uncertainty and risk of failure.

Component adaptive life management

An apparatus for the nondestructive measurement of materials that includes at least two layers of electrical conductors. Within each layer, a meandering primary winding is used to create a magnetic field for interrogating a test material while sense elements or conducting loops within each meander provide a directional measurement of the test material condition. In successive layers extended portions of the meanders are rotated so that the sense elements provide material condition in different orientations without requiring movement of the test circuit or apparatus. Multidirectional permeability measurements are used to assess the stress or torque on a component. These measurements are combined in a manner that removes temperature effects and hysteresis on the property measurements. This can be accomplished through a correction factor that accounts for the temperature dependence.

Method for stress assessment that removes temperature effects and hysteresis on the material property measurements

Described are methods for monitoring of stresses and other material properties. These methods use measurements of effective electrical properties, such as magnetic permeability and electrical conductivity, to infer the state of the test material, such as the stress, temperature, or overload condition. The sensors, which can be single element sensors or sensor arrays, can be used to periodically inspect selected locations, mounted to the test material, or scanned over the test material to generate two-dimensional images of the material properties. Magnetic field or eddy current based inductive and giant magnetoresistive sensors may be used on magnetizable and/or conducting materials, while capacitive sensors can be used for dielectric materials. Methods are also described for the use of state-sensitive layers to determine the state of materials of interest. These methods allow the weight of articles, such as aircraft, to be determined.

Magnetic field characterization of stresses and properties in materials

An apparatus for the nondestructive measurement of materials that includes at least two layers of electrical conductors. Within each layer, a meandering primary winding is used to create a magnetic field for interrogating a test material while sense elements or conducting loops within each meander provide a directional measurement of the test material condition in different orientations without requiring movement of the test circuit or apparatus. In a bidirectional implementation the meanders are oriented 90&#xb0; apart while in a quadridirectional implementation the meanders are orientated at &#x2212;45, 0, 45, and 90&#xb0;. Multidirectional permeability measurements are used to assess the stress or torque on a component. These measurements are combined in a manner that removes temperature effects and hysteresis on the property measurements. This can be accomplished through a correction factor that accounts for the temperature dependence. After the correction, the permeability measurement is then used to assess the local stresses and strains in the material of interest.

Test circuit with sense elements having associated and unassociated primary windings

Eddy current sensors and sensor arrays are used for process quality and material condition assessment of conducting materials. In an embodiment, changes in spatially registered high resolution images taken before and after cold work processing reflect the quality of the process, such as intensity and coverage. These images also permit the suppression or removal of local outlier variations. Anisotropy in a material property, such as magnetic permeability or electrical conductivity, can be intentionally introduced and used to assess material condition resulting from an operation, such as a cold work or heat treatment. The anisotropy is determined by sensors that provide directional property measurements. The sensor directionality arises from constructs that use a linear conducting drive segment to impose the magnetic field in a test material. Maintaining the orientation of this drive segment, and associated sense elements, relative to a material edge provides enhanced sensitivity for crack detection at edges.

Material condition assessment with eddy current sensors

Methods and apparatus are described for absolute electrical property measurement of materials. This is accomplished with magnetic and electric field based sensors and sensor array geometries that can be modeled accurately and with impedance instrumentation that permits accurate measurements of the in-phase and quadrature phase signal components. A dithering calibration method is also described which allows the measurement to account for background material noise variations. Methods are also described for accounting for noise factors in sensor design and selection of the optimal operating conditions which can minimize the error bounds for material property estimates. Example application of these methods to automated engine disk slot inspection and assessment of the mechanical condition of dielectric materials are presented.

Absolute property measurements using electromagnetic sensors

Magnetic or electric field sensors are mounted against a material surface and used for stress, strain, and load monitoring of rotating components such as vehicle drive trains. The stationary sensors are mounted at multiple locations around the component and used assess the stress on the component at multiple rotational positions. The sensor response is typically converted into a material property, such as magnetic permeability or electrical conductivity, which accounts for any coating thickness that may be present between the sensor and mounting surface. The sensors are not in direct contact with the rotating component and are typically mounted on an annular material or ring that encircles the rotating component. Measurements of the annular material properties, such as the stress, are related to the stress on the rotating component and discrete features on the component. As a particular example, the rotating component is a planetary gear system, with sensors mounted on the ring gear and the discrete features are carrier plate posts. The sensors are preferably mounted at equal distances around the circumference of the component. The sensors and instrumentation may be removable and reusable for monitoring of additional components.

Quasistatic magnetic and electric field stress/strain gages

Methods are described for the use of conformable eddy-current sensors and sensor arrays for characterizing residual stresses and applied loads in materials. In addition, for magnetizable materials such as steels, these methods can be used to determine carbide content and to inspect for grinding burn damage. The sensor arrays can be mounted inside or scanned across the inner surface of test articles and hollow fasteners to monitor stress distributions. A technique for placing eddy-current coils around magnetizable fasteners for load distribution monitoring is also disclosed.

Applied and residual stress measurements using magnetic field sensors

Damage and usage conditions in the vicinity of fasteners in joined structures are nondestructively evaluated using the fasteners themselves. Sensors or sensor conductors are embedded in the fasteners or integrated within the fastener construct, either in the clearance gap between the fastener and the structure material or as an insert inside the shaft or pin of the fastener. The response of the material to an interrogating magnetic or electric field is then measured with drive and sense electrodes both incorporated into the fastener or with either drive or sense electrodes external to the fastener on the material surface. In another configuration, an electric current is applied to one or more fasteners and the electric potential is measured at locations typically between the driven electrodes applying the current. The potential is measured circumferentially around the fastener at locations on the material surface or across pairs of fasteners throughout or along the joint. The voltage or potential measurement electrodes may be collinear with the drive electrodes. State sensitive material layers can be added either to the fastener or the test material layers in order to enhance observability of the test material condition, such as the presence of a crack, mechanical stress, delamination, or disbond.

Fastener and fitting based sensing methods

Combined wound and micro-fabricated winding constructs are described for the inspection of materials and the detection and characterization of hidden features or flaws. These constructs can be configured as sensors or sensor arrays that are surface mounted or scanned over conducting and/or magnetizable test materials. The well-defined geometry obtained micro-fabricated windings and from carefully wound coils with known winding positions permits the use of model based inversions of sensed responses into material properties. In a preferred embodiment, the primary winding is a wound coil and the sense elements are etched or printed. The drive or sense windings can also be mounted under fasteners to improve sensitivity to hidden flaws. Ferrites and other means may be used to guide the magnetic flux and enhance the magnetic field in the test material.

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Reading, MA, United States of America

David C Grundy