Subharmonics and beating: A new approach to Local Defect Resonance for bonded single lap joints

2019 ◽  
Vol 456 ◽  
pp. 289-305 ◽  
Author(s):  
S. Carrino ◽  
F. Nicassio ◽  
G. Scarselli
Keyword(s):  
Lap Joints ◽  
Local Defect ◽  
New Approach ◽  
Single Lap Joints ◽  
Local Defect Resonance

A New Finite Fracture Mechanics Approach for Assessing the Strength of Bonded Lap Joints

2011 ◽  
Vol 471-472 ◽  
pp. 1075-1080 ◽  
Author(s):  
Philipp Weißgraeber ◽  
Wilfried Becker
Keyword(s):  
Fracture Mechanics ◽  
Energy Release ◽  
Optimization Problem ◽  
Strength Criterion ◽  
Lap Joints ◽  
Reliable Prediction ◽  
New Approach ◽  
Single Lap Joints ◽  
Finite Fracture Mechanics ◽  
Failure Loads

For the widespread use of adhesive joints an exact and reliable prediction of the strength is mandatory. In this work, a new approach to assess the strength of single lap joints is presented. The approach is based on the hybrid criterion as postulated by Leguillon in the framework of finite fracture mechanics. It strictly combines a consideration of an energy release balance and a fulfillment of a strength criterion. The present work is based on a simple model of the joint behavior and assumptions about crack initiation. From the stress distribution of the classical shear lag theory an incremental energy release rate is derived and is used to formulate the optimization problem of the failure load. The resulting predictions of critical failure loads are compared to experimental results of single lap joints. It is shown that the new approach is able to physically describe crack formation and the corresponding critical load within the framework and limitations of the underlying assumptions and simplifications. The work closes with a discussion of the limitations and an outlook on possible improvements of the underlying models and assumptions.

scholarly journals Experimental Study of the Influence of the Surface Preparation on the Fatigue Behavior of Polyamide Single Lap Joints

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1008
Author(s):  
Francesco Musiari ◽  
Fabrizio Moroni
Keyword(s):  
Experimental Study ◽  
Fatigue Behavior ◽  
Atmospheric Pressure Plasma ◽  
Surface Preparation ◽  
Lap Joints ◽  
Polymeric Surfaces ◽  
Adhesively Bonded Joints ◽  
Single Lap Joints ◽  
Number Of Cycles ◽  
Structural Adhesive

The low quality of adhesion performance on polymeric surfaces has forced the development of specific pretreatments able to toughen the interface between substrate and adhesive. Among these methods, atmospheric pressure plasma treatment (APPT) appears particularly suitable for its environmental compatibility and its effectiveness in altering the chemical state of the surface. In this work, an experimental study on adhesively bonded joints realized using polyamide as substrates and polyurethane as the structural adhesive was carried out with the intent to characterize their fatigue behavior, which represents a key issue of such joints during their working life. The single lap joint (SLJ) geometry was chosen and several surface pretreatments were compared with each other: degreasing, abrasion (alone and followed by APPT) and finally APPT. The results show that the abrasion combined with APPT presents the most promising behavior, which appears consistent with the higher percentage of life spent for crack propagation found by means of DIC on this class of joints with respect to the others. APPT alone confers a good fatigue resistance with respect to the simple abrasion, especially at a low number of cycles to failure.

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