Wavelet Spectral Finite Element Modeling for Health Monitoring of Adhesively Bonded Joints

2016 ◽  
Author(s):  
Nimesh Jayakody ◽  
Ratneshwar Jha ◽  
Dulip Samaratunga
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Health Monitoring ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Element Modeling ◽  
Spectral Finite Element

Finite Element Modeling of Adhesively Bonded Joints

2006 ◽  
Vol 1 (1) ◽  
pp. 25-40 ◽  
Author(s):  
K.G. Muthurajan . ◽  
K. Sankaranarayanasamy . ◽  
S.B. Tiwari . ◽  
B. Nageswara Rao .
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Element Modeling

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.

Control of Void Formation in Adhesively Bonded Joints in the Presence of Filler

2020 ◽  
Vol 2020 (1) ◽  
pp. 000246-000258
Author(s):  
Nina S. Dytiuk ◽  
Thomas F. Marinis ◽  
Joseph W. Soucy
Keyword(s):  
Finite Element ◽  
Open Source ◽  
Void Formation ◽  
Adhesive Joints ◽  
Bonded Joints ◽  
Volatile Species ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Open Source Program ◽  
Source Program

Abstract Adhesively bonded joints are ubiquitous in electronic assemblies that are used in a wide range of applications, which include automotive, medical, military, space and communications. The steady drive to reduce the size of assemblies in all of these applications, while providing increased functionality, generates a need for adhesive joints of higher strength, improved thermal and electrical conductivity and better dielectric isolation. All of these attributes of adhesive joints are degraded by the presence of voids in them. The quest to minimize voids in bonded structures motivated a previous study of their formation in a solvent cast, die bond epoxy film, which undergoes a liquid phase transition during cure. That work is extended in this study by including the effects of various filler morphologies in the adhesive. Fillers are added to adhesives to facilitate handling of thin sheet formats, control bond line thickness and reduce coefficient of thermal expansion. As such, fillers are selected to be inert with respect to the adhesive chemistry, while being readily wetted by it in the liquid state. Common filler morphologies include woven and molded open meshes, fibers chopped to uniform length, and spheres of uniform or distributed diameters. Void formation is influenced by a number factors, which include wettability of the bonded surfaces, adsorbed water, amount of solvent retained in the film, volume of entrapped air, thermal profile of the cure schedule, and clamping pressure during cure. The presence of fillers in the adhesive adds the additional factors of constrained diffusion paths and increased area for void nucleation. We have changed our approach to modeling the diffusion of volatile species in adhesive joints from a finite difference calculation in a uniform adhesive medium used previously, to a finite element model of a complex diffusion space. The open source program Gmsh is used to generate the diffusion space from a set of input parameters. The calculations of concentration profiles and diffusion fluxes of volatile species at the void interface are made using the open source finite element program elmer. As done previously, the position of the void interface is updated by integrating the product of time and flux of diffusing species over the area of the interface. The internal pressure of the void is determined by application of the Young-Laplace equation, while Henry’s law is used to estimate the concentration of diffusing species adjacent to the void interface. The calculation proceeds for a time equivalent to the integral of the time temperature product required to achieve a 70% cure state of the adhesive, at which point the void interface is immobile. The experimental approach is the same as used previously, with the filled adhesive sandwiched between glass slides and cured on a hot plate while imaged through a microscope. Images are automatically captured and analyzed by using the open source program imageJ, which allows us to track the evolution of individual voids as well as the time dependent distribution of the void population. We are working to correlate these experimental results with the predictions of our finite element calculations to allow us to make insightful choices of adhesives and optimize our bonding processes.

Rate-Dependent Material Properties of Adhesively Bonded Joints - Must Have or Nice to Have?

2020 ◽  
Vol 858 ◽  
pp. 14-19
Author(s):  
Michael May
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Material Properties ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Crash Simulation ◽  
Adhesively Bonded Joints ◽  
Rate Dependent ◽  
Element Simulation ◽  
Good Agreement

In the context of automotive crash simulation, rate-dependent properties are sought for all materials undergoing deformation. Measuring rate-dependent properties of adhesively bonded joints is a challenging and associated with additional cost. This article assesses the need for having rate-dependent properties of adhesively bonded joints for the example of a typical automotive structure, an adhesively bonded metallic T-joint. Using Finite Element simulation it could be shown that good agreement between experiment and simulation was only achieved if rate-dependent properties were considered for the adhesive.

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