Crack growth in adhesively bonded joints subjected to variable frequency fatigue loading

2003 ◽  
Vol 79 (12) ◽  
pp. 1161-1182 ◽  
Author(s):  
A. H. Al-Ghamdi ◽  
I. A. Ashcroft ◽  
A. D. Crocombe ◽  
M. M. Abdel-Wahab
Keyword(s):  
Crack Growth ◽  
Fatigue Loading ◽  
Variable Frequency ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints

Integrity monitoring of adhesively bonded joints via an electromechanical impedance-based approach

2017 ◽  
Vol 17 (5) ◽  
pp. 1031-1045 ◽  
Author(s):  
Yitao Zhuang ◽  
Fotis Kopsaftopoulos ◽  
Roberto Dugnani ◽  
Fu-Kuo Chang
Keyword(s):  
Fatigue Loading ◽  
Mechanical Tests ◽  
Lap Joints ◽  
Piezoelectric Sensors ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Monitoring Method ◽  
Integrity Monitoring ◽  
Adhesively Bonded Joints ◽  
Electromechanical Impedance

Monitoring the bondline integrity of adhesively bonded joints is one of the most critical concerns in the design of aircraft structures to date. Due to the lack of confidence on the integrity of the bondline both during fabrication and service, the industry standards and regulations require assembling the primary airframe structure using the inefficient “black-aluminum” approach, that is, drill holes and use fasteners. Furthermore, state-of-the-art non-destructive evaluation and structural health monitoring approaches are not yet able to provide mature solutions on the issue of bondline integrity monitoring. Therefore, the objective of this work is the introduction and feasibility investigation of a novel bondline integrity monitoring method that is based on the use of piezoelectric sensors embedded inside adhesively bonded joints in order to provide an early detection of bondline degradation. The proposed approach incorporates (1) micro-sensors embedded inside the adhesive layer leaving a minimal footprint on the material, (2) numerical and analytical modeling of the electromechanical impedance of the adhesive bondline, and (3) electromechanical impedance–based diagnostic algorithms for monitoring and assessing the bondline integrity. The experimental validation and assessment of the proposed approach is achieved via the design and fabrication of prototype adhesively bonded lap joints with embedded piezoelectric sensors and a series of mechanical tests under various static and dynamic (fatigue) loading conditions. The obtained results demonstrate the potential of the proposed approach in providing increased confidence on the use of adhesively bonded joints for aerospace structures.

scholarly journals Impact Fatigue of Adhesive Joints

2008 ◽  
Vol 399 ◽  
pp. 71-78 ◽  
Author(s):  
Vadim V. Silberschmidt ◽  
Juan Pablo Casas-Rodriguez ◽  
Ian A. Ashcroft
Keyword(s):  
Crack Growth ◽  
Growth Process ◽  
Bonded Joints ◽  
Impact Fatigue ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Tensile Fatigue ◽  
Damage Processes ◽  
Microstructural Studies ◽  
Loading Type

The paper presents results of studies into the effect of repetitive low-energy impacting (known as impact fatigue) on reliability and crack growth in adhesively bonded joints. This type of loading is compared to the standard tensile fatigue in order to assess severity of such loading regime. Another loading type studied is a combination of a small portion of repetitive impacts with tensile fatigue. Crack propagation in a joint exposed to these types of loading is studied experimentally and numerically (with finite elements). This analysis is accompanied by microstructural studies of various damage processes, active at different stages of the crack growth process.

Experimental Characterization of Crack Growth Behavior in Adhesive Interface under Impact Loading

2016 ◽  
Vol 715 ◽  
pp. 116-121 ◽  
Author(s):  
Sota Oshima ◽  
Hisayoshi Ishida ◽  
Ryota Tanegashima ◽  
Takayuki Kusaka ◽  
Tomo Takeda
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Growth Behavior ◽  
Image Correlation ◽  
Crack Growth Behavior ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints

A novel experimental method has been developed to evaluate the mode I crack growth behavior of adhesively bonded joints under impact loading. The split Hopkinson pressure bar (SHPB) technique and the digital image correlation (DIC) technique was employed to evaluate the crack growth behavior. To reduce the dynamic effects by controlling loading input of the SHPB apparatus, the fracture toughness was determined precisely based on static evaluation formula. To contrive the testing set-up, high loading rate was kept until the arrest of crack. The fracture toughness of titanium alloy/epoxy adhesively bonded joints during crack propagation was obtained successfully by using present method.

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