scholarly journals Impact fatigue in adhesive joints

2008 ◽  
Vol 222 (10) ◽  
pp. 1981-1994 ◽  
Author(s):  
V V Silberschmidt ◽  
J P Casas-Rodriguez ◽  
I A Ashcroft
Keyword(s):  
Structural Integrity ◽  
High Energy ◽  
Epoxy Adhesive ◽  
Bonded Joints ◽  
Impact Fatigue ◽  
Adhesively Bonded ◽  
Low Velocity ◽  
Adhesively Bonded Joints ◽  
Aerospace Applications ◽  
Fatigue Crack Development

One of the forms of a vibro-impact effect in engineering components is impact fatigue (IF) caused by a cyclic repetition of low energy, low-velocity impacts, for instance, in aerospace structures. It can have a highly detrimental impact on performance and reliability of such components, exacerbated by the fact that in many cases it is disguised in loading histories by non-impact loading cycles with higher amplitudes. Since the latter are traditionally considered as most dangerous in standard fatigue, IF has not yet received deserved attention; it is less studied and practically unknown to specialists in structural integrity. Though there is a broad understanding of the danger of high-energy single impacts, repetitive impacting of components has been predominantly studied for very short series. This paper aims at the analysis of IF of adhesively bonded joints, which are becoming more broadly used in aerospace applications. The study is implemented for two types of typical adherends — an aluminium alloy and a carbon-fibre reinforced composite — and an industry-relevant epoxy adhesive. Various stages of fatigue crack development in adhesively bonded joints are studied for the conditions of standard and IF. The results obtained — in terms of crack growth rates, fatigue lives, and microstructures of fracture surfaces — are compared for the two regimes in order to find similarities and specific features.

Effect of Impact-Fatigue on Damage in Adhesive Joints

2007 ◽  
Vol 347 ◽  
pp. 653-658 ◽  
Author(s):  
Juan Pablo Casas-Rodriguez ◽  
Ian A. Ashcroft ◽  
Vadim V. Silberschmidt
Keyword(s):  
Damage Evolution ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Loading ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Bonded Joints ◽  
Impact Fatigue ◽  
Adhesively Bonded ◽  
Low Velocity

In recent decades the use of structural adhesive joints in the aerospace industry has increased considerably thanks to their high strength-to-weight ratio, low stress concentration and capacity to join different adherends. There is increasing interest in damage due to low-velocity impacts produced in adhesively bonded components and structures by vibrating loads. This type of loading is known as impact fatigue. The main aim of this paper is to investigate damage evolution in adhesive joints subjected to impact-fatigue and to compare this with damage evolution in standard fatigue (i.e. non-impacting, constant amplitude, sinusoidal fatigue). In this work, adhesively bonded lap joints were subjected to multiple tensile impacts tensile and it was seen that this type of loading was extremely damaging compared to standard fatigue. A number of methods of studying damage evolution in bonded joints subjected to fatigue and impact fatigue loading have been investigated and various parameters have been used to characterise these processes. Two modifications of the accumulated time-stress model [1-4] are proposed and it is shown that both models provide a suitable characterization of impact-fatigue in bonded joints.

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.

Fatigue Life Estimation of Adhesively Bonded Scarf Joints Based on a Continuum Damage Mechanics Model

2005 ◽  
Vol 13 (4) ◽  
pp. 359-370 ◽  
Author(s):  
Makoto Imanaka ◽  
Makoto Taniguchi ◽  
Tatuyuki Hamano ◽  
Masaki Kimoto
Keyword(s):  
Fatigue Strength ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Estimation Method ◽  
Adhesive Layer ◽  
Epoxy Adhesive ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Scarf Joints

An estimation method of fatigue strength of adhesively bonded joints with various stress triaxialities in the adhesive layer has been proposed based on a damage evolution model for high cycle fatigue. To realize various triaxial stress states, fatigue test was conducted for adhesively bonded butt and scarf joints with various scarf angles bonded by a rubber-modified epoxy adhesive. An equation for estimating the damage evolution in the adhesive layer of the butt and scarf joints was derived from the damage model, where undefined parameters in the equation were determined by comparing the experimentally obtained damage evolution curves of the butt joints with the estimated damage evolution curves. Furthermore, an equation for the estimation of fatigue strength was derived under the assumption that fatigue failure occurs when the damage variable reaches to a critical value. When compared the experimental S-N data of scarf joints with the estimated ones, the estimated fatigue strengths agree well with the experimental data with various scarf angles. This finding suggests that the CDM model is applicable for estimating fatigue strength of adhesively bonded joints with different stress triaxialities.

Temperature Effect on the Shear Strength of Adhesively Bonded Joints

2013 ◽  
Vol 758 ◽  
pp. 119-124 ◽  
Author(s):  
Kenji R. Osanai ◽  
João M.L. Reis
Keyword(s):  
Shear Strength ◽  
Strength Loss ◽  
Work Conditions ◽  
Epoxy Adhesive ◽  
Lap Joints ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Single Lap Joints ◽  
Made In

The purpose of this paper is to study some of the factors that affect the shear strength of Single Lap Joints (SLJ). Based in work conditions for different applications, tests were made in order to define the influence of geometry and temperature on the strength of SLJ under shear load. The adhesive used to make the joints was the epoxy adhesive ARC858 and it was tested under temperatures ranging between 21°C and 70°C and overlap length of 12.5mm and 18.75mm. Results of those tests showed that shear strength increased due to geometry with an overlap of 18.75mm and a great shear strength loss ranging from 30°C to 50°C. The failure mechanism was adhesive failure.

Study on Response of Adhesively Bonded Joints under Transverse Impact

2012 ◽  
Vol 251 ◽  
pp. 450-454
Author(s):  
Jian Guang Zhang ◽  
Krishan K. Chawla ◽  
Uday K. Vaidya
Keyword(s):  
Impact Strength ◽  
Lap Joints ◽  
Bonded Joints ◽  
Transverse Impact ◽  
Adhesively Bonded ◽  
Low Velocity ◽  
Adhesively Bonded Joints ◽  
Glass Fiber Reinforced ◽  
The Impact ◽  
Good Agreement

The response of adhesively bonded joints subjected to a transverse impact was investigated. The joints were bonded by two-part acrylic adhesive DP8005 with using two types of adherents, polypropylene and glass fiber reinforced polypropylene. The lap joints were impacted by a drop weight with hemisphere tip at a low velocity. An energy model was applied to evaluate the effect of the properties and thickness of adherents on the impact strength of the joints. The results from model showed good agreement with those from experiments.

Nonlinear Viscoelastic Finite Element Analysis of Adhesive Joints

1988 ◽  
Vol 16 (3) ◽  
pp. 146-170 ◽  
Author(s):  
S. Roy ◽  
J. N. Reddy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Viscoelastic Behavior ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Element Analysis ◽  
Adhesively Bonded Joints ◽  
Nonlinear Viscoelastic ◽  
Structural Failures ◽  
Updated Lagrangian

Abstract A good understanding of the process of adhesion from the mechanics viewpoint and the predictive capability for structural failures associated with adhesively bonded joints require a realistic modeling (both constitutive and kinematic) of the constituent materials. The present investigation deals with the development of an Updated Lagrangian formulation and the associated finite element analysis of adhesively bonded joints. The formulation accounts for the geometric nonlinearity of the adherends and the nonlinear viscoelastic behavior of the adhesive. Sample numerical problems are presented to show the stress and strain distributions in bonded joints.

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