M. Grujicic, G. Arakere, V. Sellappan, J.C. Ziegert and D. Schmueser
Among various efforts pursued to produce fuel efficient vehicles, light weight engineering (i.e. the use of low‐density structurally‐efficient materials, the application of…
Abstract
Among various efforts pursued to produce fuel efficient vehicles, light weight engineering (i.e. the use of low‐density structurally‐efficient materials, the application of advanced manufacturing and joining technologies and the design of highly‐integrated, multi‐functional components/sub‐assemblies) plays a prominent role. In the present work, a multi‐disciplinary design optimization methodology has been presented and subsequently applied to the development of a light composite vehicle door (more specifically, to an inner door panel). The door design has been optimized with respect to its weight while meeting the requirements /constraints pertaining to the structural and NVH performances, crashworthiness, durability and manufacturability. In the optimization procedure, the number and orientation of the composite plies, the local laminate thickness and the shape of different door panel segments (each characterized by a given composite‐lay‐up architecture and uniform ply thicknesses) are used as design variables. The methodology developed in the present work is subsequently used to carry out weight optimization of the front door on Ford Taurus, model year 2001. The emphasis in the present work is placed on highlighting the scientific and engineering issues accompanying multidisciplinary design optimization and less on the outcome of the optimization analysis and the computational resources/architecture needed to support such activity.
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Lokamanya Chikmath, M.N. Ramanath, Syed Imtiaz and H. Murthy
This paper aims to study the benefits of use of bi-adhesive (combination of two different adhesives) over conventional single adhesive in bonded lap joints. Characterise damage…
Abstract
Purpose
This paper aims to study the benefits of use of bi-adhesive (combination of two different adhesives) over conventional single adhesive in bonded lap joints. Characterise damage severity due to cohesive and adherent failure as feedback for operating load levels that assist in developing damage tolerance design of the adhesively bonded joints.
Design/methodology/approach
Single lap joint where the adherent plate is made up of aluminium alloy joined together with bi-adhesives is analysed. The nature of adhesives ranges from brittle, elastic-plastic, moderately ductile to largely ductile. Numerical analysis is performed considering the material and geometric non-linear behaviour of the joint. The optimum bond ratio of bi-adhesives and the effect of the location of adhesive on the stress distribution are studied. The cohesive zone modelling (CZM) is adopted to account for the cohesive failure of the joint. The adherent plate failure is also addressed by modelling and studying the behaviour of the crack at different locations in the plate using modified virtual crack closure integral (MVCCI).
Findings
The results obtained from the stress analysis show some important characteristic behaviour of the bi-adhesive joint. Although bi-adhesive is expected to result in improved joint strength, the purpose gets defeated if a brittle adhesive is used at the corners and ductile adhesive at the middle. The joint strength based on CZM, evaluated for a single adhesive, is in good comparison with the experimental results from the literature. Also, the location of the crack in the adherent plate plays a significant role in the failure of the joint.
Originality/value
Estimating joint strength for the bi-adhesive model using CZM and evaluating damage severity in the presence of de-bond and crack in the bi-adhesive lap joint model assists in developing robust damage tolerance design models of such joints.
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Leslie Banks‐Sills, Natalie Konovalov and Adi Fliesher
Fracture tests carried out on bimaterial Brazilian disk specimens have been reported elsewhere. Two material pairs are tested in which each of the constituents is linearly…
Abstract
Purpose
Fracture tests carried out on bimaterial Brazilian disk specimens have been reported elsewhere. Two material pairs are tested in which each of the constituents is linearly elastic, isotropic, and homogeneous. For this material type, the crack fields decouple into in‐plane and out‐of‐plane deformation. Hence, a two‐dimensional approach is taken to analyse the tests. The purpose of this paper is to examine the necessity of using a three‐dimensional approach to predict interface fracture when in‐plane loading is applied.
Design/methodology/approach
To this end, the specimens are analysed by means of two‐ and three‐dimensional finite elements. The interaction energy or M‐integral is used to calculate the stress intensity factors.
Findings
The paper shows that the Mode III stress intensity factor KIII is not negligible near the specimen outer surfaces. Nevertheless, a two‐dimensional analysis will be seen to be sufficient to analyse these tests. This has implications for the practical engineer.
Originality/value
The paper offers a comparison between two‐ and three‐dimensional fracture criteria for a crack along the interface between two homogeneous, isotropic, linear elastic materials when in‐plane loading is applied to the body, and assesses the importance of the out‐of‐plane deformation.
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The purpose of this paper is to improve the framework of classical collaborative optimization (CCO) so as to solve the multi-disciplinary optimization problems with parametric and…
Abstract
Purpose
The purpose of this paper is to improve the framework of classical collaborative optimization (CCO) so as to solve the multi-disciplinary optimization problems with parametric and parameter-free variables, and therefore an improved collaborative optimization (ICO) is proposed.
Design/methodology/approach
To clarify the relation of design variables, the optimization problem is classified into three general case. For each case, the respective treatment is suggested for coupled or uncoupled variables in the framework of the ICO.
Findings
The decoupling treatment suggested in the ICO framework not only avoids the iteration divergence and thus optimization failure, but increases the optimal design space to some extent. The method is validated by optimizing an aircraft assembly and a high-speed train assembly.
Originality/value
The two practical examples proves that the present ICO succeeds in solving the problem that the CCO failed to, also gives the optimal results better than those from the sequential optimization method.