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| 2. |
- Ahlström, Johan, 1969, et al.
(författare)
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Modeling of Distortion during Casting and Machining of Aluminum Engine Blocks with Cast-in Gray Iron Liners
- 2012
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Ingår i: Materials Performance and Characterization. - 2165-3992. ; 9:5, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- A method for quantifying distortions arising in engine blocks of aluminium with liners of grey iron has been developed based on virtual finite element based simulation tools. The key processing steps comprise the convection cooling step, associated with shrinkage and residual stress build-up, and the machining step. The engine block has been modelled using the finite element method and machining has been simulated using the element-removal technique. The mechanical behaviour of aluminium has been characterised by tensile tests at different temperatures and strain rates. The results were used for calibration of material models capturing the viscoplastic behaviour at higher temperatures. Finally, following the key process steps, results from a complete process analysis are reported comprising the initial stress build-up based on the cooling associated with initial out-of-roundness and predictions of final residual stress state in the block and out-of-roundness of the liners after various machining operations.
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| 3. |
- Ahlström, Johan, 1969, et al.
(författare)
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Modelling of distortion during casting and machining
- 2010
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Ingår i: Conference proceedings ICTPMCS-2010, 31 May – 2 June 2010, Shanghai, China. ; , s. 8 pp-
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Konferensbidrag (refereegranskat)abstract
- A method for quantifying distortions arising in engine blocks of aluminium with liners of grey iron has been developed. The engine block has been modelled using the finite element method and machining has been simulated using the element-removal technique. The mechanical behaviour of aluminium has been characterised by tensile tests at different temperatures and strain rates. The results were used for calibration of material models capturing the viscoplastic behaviour at higher temperatures.
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| 4. |
- Ansin, Caroline, 1996, et al.
(författare)
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Fast simulation of 3D elastic response for wheel–rail contact loading using Proper Generalized Decomposition
- 2023
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825. ; 417
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Tidskriftsartikel (refereegranskat)abstract
- To increase computational efficiency, we adopt Proper Generalized Decomposition (PGD) to solve a reduced-order problem of the displacement field for a three-dimensional rail head exposed to different contact scenarios. The three-dimensional solid rail head is modeled as a two-dimensional cross-section, with the coordinate along the rail being treated as a parameter in the PGD approximation. A novel feature is that this allows us to solve the full three-dimensional model with a nearly two-dimensional computational effort. Additionally, we incorporate the distributed contact load predicted from dynamic vehicle-track simulations as extra coordinates in the PGD formulation, using a semi-Hertzian contact model. The problem is formulated in two ways; one general ansatz which considers the treatment of numerous parameters, some of which exhibit a linear influence, and a linear ansatz where multiple PGD solutions are solved for. In particular, situations where certain parameters become invariant are handled. We assess the accuracy and efficiency of the proposed strategy through a series of verification examples. It is shown that the PGD solution converges towards the FE solution with reduced computational cost. Furthermore, solving for the PGD approximation based on load parameterization in an offline stage allows expedient handling of the wheel-rail contact problem online.
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| 5. |
- Ansin, Caroline, 1996, et al.
(författare)
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Simulation and Field Measurements of the Long-term Rail Surface Damage due to Plasticity, Wear and Surface Rolling Contact Fatigue Cracks in a Curve
- 2022
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Ingår i: CM 2022 - 12th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Conference Proceedings. ; , s. 591-601
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Konferensbidrag (refereegranskat)abstract
- A methodology that simulates the long-term rail surface damage in a cross-section of a curve for a given traffic scenario is presented. The numerical model considers plastic deformation, wear, and initiation of rolling contact fatigue (RCF) surface cracks. The models and simulations are calibrated and validated, respectively, against field profile measurement data.
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| 6. |
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| 7. |
- Blinzler, Brina, 1987, et al.
(författare)
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A Mechanics Based Surface Image Interpretation Method for Multifunctional Nanocomposites
- 2019
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 9:11, s. 1578-
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Tidskriftsartikel (refereegranskat)abstract
- Graphene nanosheets and thicker graphite nanoplatelets are being used as reinforcement in polymeric materials to improve the material properties or induce new functional properties. By improving dispersion, de-agglomerating the particles, and ensuring the desired orientation of the nano-structures in the matrix, the microstructure can be tailored to obtain specific material properties. A novel surface image assisted modeling framework is proposed to understand functional properties of the graphene enhanced polymer. The effective thermal and mechanical responses are assessed based on computational homogenization. For the mechanical response, the 2-D nanoplatelets are modeled as internal interfaces that store energy for membrane actions. The effective thermal response is obtained similarly, where 2-D nanoplatelets are represented using regions of high conductivity. Using the homogenization simulation, macroscopic stiffness properties and thermal conductivity properties are modeled and then compared to the experimental data. The proposed surface image assisted modeling yields reasonable effective mechanical and thermal properties, where the Kapitza effect plays an important part in effective thermal properties.
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| 8. |
- de Oliveira, Sergio, et al.
(författare)
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Failure prediction in fiber-reinforced composites based on continuum damage mechanics
- 2019
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Ingår i: Proceedings - 7th ECCOMAS THEMATIC CONFERENCE ON THE MECHANICAL RESPONSE OF COMPOSITES.
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Konferensbidrag (refereegranskat)abstract
- The paper presents an approach to intra/inter-laminar failure modeling of fiber reinforced composites using continuum damage. The intra-laminar damage model is based on elastic damage, focusing propagation of damage for compression dominated loadings. A special feature is the study on ply elasticity, induced by graphene enhancement of the polymer matrix linked to the damage evolution. The results shows that the considered intra-laminar composite response is only slight affected by the graphene. The open hole compression test involves mechanisms of both intra- and interlaminar failure. The results show a fairly good correlation between the experiments and the proposed model.
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| 9. |
- Dutra, Thiago, 1985, et al.
(författare)
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Expanding Puck and Schürmann Inter Fiber Fracture Criterion for Fiber Reinforced Thermoplastic 3D-Printed Composite Materials
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:7
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Tidskriftsartikel (refereegranskat)abstract
- The present work expands the application of Puck and Schürmann Inter-Fiber Fracture criterion to fiber reinforced thermoplastic 3D-printed composite materials. The effect of the ratio between the transverse compressive strength and the in-plane shear strength is discussed and a new transition point between the fracture conditions under compressive loading is proposed. The recommended values of the inclination parameters, as well as their effects on the proposed method, are also discussed. Failure envelopes are presented for different 3D-printed materials and also for traditional composite materials. The failure envelopes obtained here are compared to those provided by the original Puck and Schürmann criterion and to those provided by Gu and Chen. The differences between them are analyzed with the support of geometrical techniques and also statistical tools. It is demonstrated that the Expanded Puck and Schürmann is capable of providing more suitable failure envelopes for fiber reinforced thermoplastic 3D-printed composite materials in addition to traditional semi-brittle, brittle and intrinsically brittle composite materials.
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| 10. |
- Ertürk, Ahmet Semih, 1991, et al.
(författare)
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A thermomechanically motivated approach for identification of flow stress properties in metal cutting
- 2020
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 111:3-4, s. 1055-1068
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a novel thermomechanically coupled distributed primary deformation zone model to assist the inverse identification of Johnson-Cook material parameters to be used for machining simulations. A special feature of the enhanced model is that the assumed stress field is temperature-dependent, where the thermomechanical coupling governs the stress and temperature distributions across the primary shear zone to describe the thermal softening effect. By using stress, strain, strain rate, and temperature distributions from the thermomechanically enhanced model, Johnson-Cook material parameters are calibrated for orthogonal cutting tests of C38, 42CrMo4, and AA6082 materials where continuous chip formation prevails. The performance of the parameters is compared with that of a wider set of cutting tests using finite element simulations. The results show that the thermomechanically motivated model yields closer results to experiments in terms of cutting force and chip thickness (9% and 34% difference, respectively) compared with the original thermally uncoupled model (47% and 92% difference, respectively). Identification of the material parameters by this method focuses directly on the orthogonal cutting test and it does not require many experiments or simulations. In fact, the proposed methodology is computationally robust and cost-efficient which makes it preferable compared with other methods which are more accurate but highly time-consuming.
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