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- Al-Ramahi, Nawres J., 1980-, et al.
(författare)
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Numerical stress analysis for single-lap adhesive joint under thermo-mechanical load using non-linear material
- 2020
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Ingår i: The 3rd International Conference on Sustainable Engineering Techniques (ICSET20). - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- A comprehensive stress analysis by means of Finite Element Method (FEM) for single-lap joint subjected to thermal and mechanical loads is presented in this paper. Simulation is used to predict the effect of residual thermal stresses (caused by difference of temperature of use and elevated temperature during the assembly of the joint) on stress distribution within adhesive layer. The residual thermal stresses are assigned to joint members as initial condition before the mechanical load is applied. The FEM model employs linear and nonlinear material model and accounts for geometrical nonlinearity. It is confirmed that the difference between the manufacturing and the ambient temperature results in high residual thermal stresses, especially in axial and lateral directions of the joint. The calculation of total stress as superposition of thermal and mechanical stresses works only for linear materials. Moreover, simultaneous application of temperature and mechanical load (applied strain in case of displacement controlled test) in FEM produces inaccurate results, since in real situation the strain is applied to already thermally loaded structure. It is also found that the residual thermal stresses may reduce the peel and shear stress concentration in the adhesive at the ends of overlap and the shear stress within the overlap.
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| 2. |
- Andersons, J., et al.
(författare)
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Prediction of crack onset strain in composite laminates at mixed mode cracking
- 2009
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Ingår i: 5th International EEIGM/AMASE/FORGEMAT Conference on Advanced Materials Research. - Bristol : IOP Publishing Ltd.
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Konferensbidrag (refereegranskat)abstract
- Failure process of continuous fiber reinforced composite laminates in tension usually starts with appearance of intralaminar cracks. In composite laminates with complex lay-ups and/or under combined loading, intralaminar cracks may develop in plies with different reinforcement directions. A necessary part of mixed mode cracking models is the criterion of failure. For propagation-controlled fracture it is usually formulated in terms of energy release rates and their critical values of the particular composite material. Intralaminar fracture toughness of unidirectionally reinforced glass/epoxy composite was experimentally determined at several mode I and mode II ratios. It is found that the crack propagation criterion, linear in terms of the energy release rates, reasonably well approximates the test results. The determined mixed mode cracking criterion was applied to predict intralaminar crack onset in cross-ply glass/epoxy composite under tensile loading. The predicted crack onset strain values agree with test results at small off-axes angles of the cracking ply (on-axis and 15° off-axis loading), but underestimate crack onset at larger reinforcement angles with respect to the loading direction. The discrepancy is likely to be caused by the deviation of linearity in laminate response before cracking onset in these laminates, related to non-linear shear characteristics of unidirectional plies. The applicability of strength-based fracture criterion for initiation-controlled cracking is discussed.
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