Detection of fatigue cracks and torque loss in bolted joints

Clyde K. Coelho; Santanu Das; Aditi Chattopadhyay; Antonia Papandreou-Suppappola; Pedro Peralta

doi:10.1117/12.715984

11 April 2007 Detection of fatigue cracks and torque loss in bolted joints

Clyde K. Coelho, Santanu Das, Aditi Chattopadhyay, Antonia Papandreou-Suppappola, Pedro Peralta

Proceedings Volume 6532, Health Monitoring of Structural and Biological Systems 2007; 653204 (2007) https://doi.org/10.1117/12.715984
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2007, San Diego, California, United States

Abstract

Fatigue crack growth during the service life of aging aircraft is a critical issue and monitoring of such cracks in structural hotspots is the goal of this research. This paper presents a procedure for classification and detection of cracks generated in bolted joints which are used at numerous locations in aircraft structures. Single lap bolted joints were equipped with surface mounted piezoelectric (pzt) sensors and actuators and were subjected to cyclic loading. Crack length measurements and sensor data were collected at different number of cycles and with different torque levels. A classification algorithm based on Support Vector Machines (SVMs) was used to compare signals from a healthy and damaged joint to classify fatigue damage at the bolts. The algorithm was also used to classify the amount of torque in the bolt of interest and determine if the level of torque affected the quantification and localization of the crack emanating from the bolt hole. The results show that it is easier to detect the completely loose bolt but certain changes in torque, combined with damage, can produce some non-unique classifier solutions.

Citation Download Citation

Clyde K. Coelho, Santanu Das, Aditi Chattopadhyay, Antonia Papandreou-Suppappola, and Pedro Peralta "Detection of fatigue cracks and torque loss in bolted joints", Proc. SPIE 6532, Health Monitoring of Structural and Biological Systems 2007, 653204 (11 April 2007); https://doi.org/10.1117/12.715984

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