Active Washers for Bolted Joint Inspection
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Solution Overview
Problem
Current methods for inspecting bolted joints, such as shear wave ultrasonic beams and eddy current techniques, are labor-intensive, prone to human error, and limited in detecting defects like delamination and fatigue cracking, especially in hard-to-access areas, and existing smart washers struggle with noise differentiation and material limitations.
Innovation Solution
Active washers integrated with ultrasonic transducers are used to non-destructively inspect bolted joints, providing continuous monitoring and reducing the need for manual access by transmitting and receiving inspection signals, allowing for early detection of defects through pulse-echo or through-transmission modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual inspection methods (shear wave ultrasonic beam or eddy current) are used to inspect bolted joints, then inspection capability is provided, but labor intensity increases and human error is introduced
Solution Approach 1:
The washer performs self-inspection by incorporating an inspection sensor that continuously monitors the bolted joint for defects such as delamination and fatigue cracking. The sensor is powered by a battery integrated into the washer, enabling autonomous operation without external inspection equipment or personnel intervention.
Solution Approach 2:
The patent replaces manual mechanical inspection methods (ultrasonic beams and eddy current probes operated by inspectors) with an automated electronic sensing system integrated into the washer. The inspection sensor electronically detects structural defects and transmits data wirelessly, eliminating the need for manual scanning and real-time interpretation.
2Ease of operation
If access panels, hydraulic lines, cables, hoses, brackets, and other interfering structures are removed to gain access to inspection areas, then inspection access is improved, but time and labor increase
Solution Approach 1:
The inspection sensor is integrated directly into the washer, which is already part of the bolted joint assembly. This eliminates the need to remove access panels, hydraulic lines, cables, hoses, or brackets to reach the inspection area. The sensor continuously monitors the joint from its original position, providing inspection data without requiring structural disassembly.
3Measurement precision
If the inspection area surface is prepared by scraping away sealant fillets to provide a clean surface, then sensor contact is improved, but labor and time are increased
Solution Approach 1:
The inspection sensor is pre-integrated into the washer during manufacturing, with the sensor position and contact surface predetermined. This preliminary integration eliminates the need for on-site surface preparation by scraping sealant fillets. The sensor is already positioned to contact the joint surface at the correct angle and location when the washer is installed.
4Measurement precision
If an operator must know how to place and orient a transducer or probe to ensure optimum angle for defect examination, then inspection quality is improved, but skill requirements and human error increase
Solution Approach 1:
The optimal sensor orientation and positioning are predetermined during the washer manufacturing process. The inspection sensor is integrated at the correct angle and position relative to the bolt hole to detect defects from the optimum direction. This eliminates the need for the operator to determine sensor placement and orientation, reducing skill requirements and human error.
5Reliability
If an operator must interpret and evaluate inspection data in real-time to determine significant defects, then immediate detection is achieved, but human error and subjectivity are introduced
Solution Approach 1:
The inspection sensor continuously monitors the bolted joint and provides real-time feedback data wirelessly to a remote location. The system automatically compares current sensor readings against baseline data to detect changes indicating defect growth. This automated feedback mechanism eliminates real-time human interpretation, providing objective, reliable defect detection.
Solution Approach 2:
The patent replaces the operator's real-time visual and analytical interpretation of inspection data with an automated electronic data transmission and processing system. The sensor electronically detects defect signals, transmits them wirelessly, and enables remote evaluation without requiring the operator to be physically present at the inspection location.
6Reliability
If existing smart washers with eddy current sensors are used, then continuous monitoring is achieved, but noise differentiation capability is insufficient and material limitations exist
Solution Approach 1:
The patent replaces eddy current sensing with ultrasonic sensing technology. The inspection sensor uses ultrasonic waves to detect structural defects such as delamination and fatigue cracking. This substitution provides superior noise differentiation capability and expands material compatibility beyond electrically conductive surfaces, while maintaining continuous monitoring functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Active washers enable remote, efficient, and accurate detection of defects in bolted joints, reducing maintenance costs and frequency by providing continuous monitoring and early detection of delamination and fatigue cracking, even in difficult-to-access areas, with improved signal-to-noise ratio and reduced human error.
Implementation Method 1
A feature of airplanes and other vehicles and structures that is critical to structural integrity is the bolted joint, including the bolted composite joint. Of concern for bolted composite joints is the potential for defects such as delamination and fatigue cracking around the bolt-holes.
Data Source
AI summary
Apparatus, systems, and methods for inspecting and monitoring bolted joints of metallic and composite structures for defects such as delamination and fatigue cracking are provided that incorporate ultrasonic transducers with load bearing washers. These active washers may be used for inspecting and monitoring a structure beneath such load bearing fasteners as bolts and nuts. Active washers may be used for continuous, periodic, and controlled inspections of bolted joints. Ultrasonic transducers may be permanently applied to a surface of a washer or recessed in a cavity on a surface of the washer. Inspection signals may be transmitted from ultrasonic transducers into a structure and reflected in pulse-echo application or received by another active washer on the opposing side of the structure in a through-transmission application.