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Olsson, P. A. T., Hyldgaard, P., Schroder, E., Jutemar, E. P., Andreasson, E. & Kroon, M. (2018). Ab initio investigation of monoclinic phase stability and martensitic transformation in crystalline polyethylene. PHYSICAL REVIEW MATERIALS, 2(7), Article ID 075602.
Öppna denna publikation i ny flik eller fönster >>Ab initio investigation of monoclinic phase stability and martensitic transformation in crystalline polyethylene
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2018 (Engelska)Ingår i: PHYSICAL REVIEW MATERIALS, ISSN 2475-9953, Vol. 2, nr 7, artikel-id 075602Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We study the phase stability and martensitic transformation of orthorhombic and monoclimic polyethylene by means of density functional theory using the nonempirical consistent-exchange vdW-DF-cx functional [Phys. Rev. B 89, 035412 (2014)]. The results show that the orthorhombic phase is the most stable of the two. Owing to the occurrence of soft librational phonon modes, the monoclimic phase is predicted not to be stable at zero pressure and temperature, but becomes stable when subjected to compressive transverse deformations that pin the chains and prevent them from wiggling freely. This theoretical characterization, or prediction, is consistent with the fact that the monoclimic phase is only observed experimentally when the material is subjected to mechanical loading. Also, the estimated threshold energy for the combination of lattice deformation associated with the T1 and T2 transformation paths (between the orthorhombic and monoclimic phases) and chain shuffling is found to be sufficiently low for thermally activated back transformations to occur. Thus, our prediction is that the crystalline part can transform back from the monoclimc to the orthorhombic phase upon unloading and/or annealing, which is consistent with experimental observations. Finally, we observe how a combination of such phase transformations can lead to a fold-plane reorientation from {110} to {100} type in a single orthorhombic crystal.

Ort, förlag, år, upplaga, sidor
AMER PHYSICAL SOC, 2018
Nationell ämneskategori
Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-16896 (URN)10.1103/PhysRevMaterials.2.075602 (DOI)000438044900003 ()
Tillgänglig från: 2018-08-20 Skapad: 2018-08-20 Senast uppdaterad: 2018-08-20Bibliografiskt granskad
Olsson, P., in ’t Veld, P. J., Andreasson, E., Bergvall, E., Persson Jutemar, E., Petersson, V., . . . Kroon, M. (2018). All-atomic and coarse-grained molecular dynamics investigation of deformation in semi-crystalline lamellar polyethylene. Polymer, 153, 305-316
Öppna denna publikation i ny flik eller fönster >>All-atomic and coarse-grained molecular dynamics investigation of deformation in semi-crystalline lamellar polyethylene
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2018 (Engelska)Ingår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 153, s. 305-316Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

In the present work we have performed classical molecular dynamics modelling to investigate the effects of different types of force-fields on the stress-strain and yielding behaviours in semi-crystalline lamellar stacked linear polyethylene. To this end, specifically the all-atomic optimized potential for liquid simulations (OPLS-AA) and the coarse-grained united-atom (UA) force-fields are used to simulate the yielding and tensile behaviour for the lamellar separation mode. Despite that the considered samples and their topologies are identical for both approaches, the results show that they predict widely different stress-strain and yielding behaviours. For all UA simulations we obtain oscillating stress-strain curves accompanied by repetitive chain transport to the amorphous region, along with substantial chain slip and crystal reorientation. For the OPLS-AA modelling primarily cavitation formation is observed, with small amounts of chain slip to reorient the crystal such that the chains align in the tensile direction. This force-field dependence is rooted in the lack of explicit H-H and C-H repulsion in the UA approach, which gives rise to underestimated ideal critical resolved shear stress. The computed critical resolved shear stress for the OPLS-AA approach is in good agreement with density functional theory calculations and the yielding mechanisms resemble those of the lamellar separation mode. The disparate energy and shear stress barriers for chain slip of the different models can be interpreted as differently predicted intrinsic activation rates for the mechanism, which ultimately are responsible for the observed diverse responses of the two modelling approaches. © 2018 Elsevier Ltd

Ort, förlag, år, upplaga, sidor
Elsevier Ltd, 2018
Nyckelord
Molecular dynamics, Plasticity, Semi-crystalline polyethylene, Atoms, Chains, Crystalline materials, Density functional theory, Polyethylenes, Shear stress, Classical molecular dynamics, Coarse-grained molecular dynamics, Critical resolved shear stress, Crystal reorientation, Linear polyethylene, Liquid simulations, Semicrystallines, Yielding mechanisms, Stress-strain curves
Nationell ämneskategori
Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-16976 (URN)10.1016/j.polymer.2018.07.075 (DOI)000445783300034 ()2-s2.0-85051682841 (Scopus ID)
Tillgänglig från: 2018-09-06 Skapad: 2018-09-06 Senast uppdaterad: 2018-10-18Bibliografiskt granskad
Kroon, M., Andreasson, E., Persson Jutemar, E., Petersson, V., Persson, L., Dorn, M. & Olsson, P. (2018). Anisotropic Elastic-Viscoplastic Properties at Finite Strains of Injection-Moulded Low-Density Polyethylene. Experimental mechanics, 58(1), 75-86
Öppna denna publikation i ny flik eller fönster >>Anisotropic Elastic-Viscoplastic Properties at Finite Strains of Injection-Moulded Low-Density Polyethylene
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2018 (Engelska)Ingår i: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 58, nr 1, s. 75-86Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters. © 2017 The Author(s)

Ort, förlag, år, upplaga, sidor
Springer New York LLC, 2018
Nyckelord
Anisotropic, Constitutive behaviour, Elasticity, Injection-moulding, LDPE, Polyethylene, Tensile, Viscoplasticity, Anisotropy, Low density polyethylenes, Mechanical properties, Molding, Plasticity, Plates (structural components), Polyethylenes, Polymers, Strain, Tensile testing, Thin walled structures, Anisotropic elastic, Compliance matrixes, Elastic-viscoplasticity, Manufacturing process, Monotonic and cyclic loading, Injection molding
Nationell ämneskategori
Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-15095 (URN)10.1007/s11340-017-0322-y (DOI)000418799700006 ()2-s2.0-85027718634 (Scopus ID)
Forskningsfinansiär
KK-stiftelsen, 20150165
Anmärkning

Open access

Tillgänglig från: 2017-09-01 Skapad: 2017-09-01 Senast uppdaterad: 2019-03-28Bibliografiskt granskad
Kroon, M., Andreasson, E., Petersson, V. & Olsson, P. (2018). Experimental and numerical assessment of the work of fracture in injection-moulded low-density polyethylene. Engineering Fracture Mechanics, 192, 1-11
Öppna denna publikation i ny flik eller fönster >>Experimental and numerical assessment of the work of fracture in injection-moulded low-density polyethylene
2018 (Engelska)Ingår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, ISSN 0013-7944, Vol. 192, s. 1-11Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The fracture mechanics properties of injection-moulded low-density polyethylene (LDPE) sheets were investigated both experimentally and numerically. The total work of fracture was determined experimentally, by means of fracture mechanics testing of sheets of injection-moulded LDPE with side cracks of different lengths. A multi-specimen method, proposed by Kim and Joe (1987), was employed. The total work of fracture was estimated to 13 kJ/m2. The experiments were simulated numerically using the finite element method. Crack growth was enabled by inclusion of a cohesive zone, and the constitutive response of this zone was governed by a traction-separation law. The local (or essential) work of fracture was estimated through numerical analyses, where the initiation of crack growth was simulated and the outcome was compared to the experimental results. The local (i.e. essential) work of fracture was estimated to 1.7 kJ/m2, which is consistent with previous experimental measurements for the material in question. The total work of fracture, retrieved from the present experiments, agreed well with the far field values of the J-integral in the numerical analyses. © 2018 The Authors

Ort, förlag, år, upplaga, sidor
Elsevier, 2018
Nyckelord
Abaqus, Cohesive Energy, FEM, Fracture, Injection-moulding, Low-density, Polyethylene
Nationell ämneskategori
Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-15972 (URN)10.1016/j.engfracmech.2018.02.004 (DOI)000427628100001 ()
Anmärkning

open access

Tillgänglig från: 2018-03-22 Skapad: 2018-03-22 Senast uppdaterad: 2018-04-06Bibliografiskt granskad
Tabourot, L., Charleux, L., Balland, P., Sène, N. A. & Andreasson, E. (2018). Experimental characterization and microstructure linked modeling of mechanical behavior of ultra-thin aluminum foils used in packaging. In: PROCEEDINGS OF 21ST INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING (ESAFORM 2018): . Paper presented at 21st International ESAFORM Conference on Material Forming, ESAFORM, Palermo. American Institute of Physics Inc., 1960, Article ID UNSP 170016.
Öppna denna publikation i ny flik eller fönster >>Experimental characterization and microstructure linked modeling of mechanical behavior of ultra-thin aluminum foils used in packaging
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2018 (Engelska)Ingår i: PROCEEDINGS OF 21ST INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING (ESAFORM 2018), American Institute of Physics Inc. , 2018, Vol. 1960, artikel-id UNSP 170016Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

This paper is based on the hypothesis that introducing distribution of mechanical properties is beneficial for modeling all kinds of mechanical behavior, even of ordinary metallic materials. To bring proof of its admissibility, it has to be first shown that modeling based on this assertion is able to efficiently describe standard mechanical behavior of materials. Searching for typical study case, it has been assessed that at a low scale, yield stresses could be strongly distributed in ultrathin aluminum foils used in packaging industry, offering opportunities to identifying their distribution and showing its role on the mechanical properties. Considering initially reduced modeling allow to establish a valuable connection between the hardening curve and the distribution of local yield stresses. This serves for finding initial value of distribution parameters in a more sophisticated identification procedure. With finally limited number of representative classes of local yield stresses, concretely 3 is enough, it is shown that a 3D finite element simulation involving limited numbers of elements returns realistic behavior of an ultrathin aluminum foil exerted to tensile test, in reference to experimental results. This gives way to large possibilities in modeling in order to give back complex experimental evidence. © 2018 Author(s).

Ort, förlag, år, upplaga, sidor
American Institute of Physics Inc., 2018
Serie
AIP Conference Proceedings, ISSN 0094-243X
Nationell ämneskategori
Metallurgi och metalliska material Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-16336 (URN)10.1063/1.5035073 (DOI)000432776900272 ()2-s2.0-85047347375 (Scopus ID)9780735416635 (ISBN)
Konferens
21st International ESAFORM Conference on Material Forming, ESAFORM, Palermo
Tillgänglig från: 2018-06-07 Skapad: 2018-06-07 Senast uppdaterad: 2018-06-18Bibliografiskt granskad
Olsson, P. A. .., Schröder, E., Hyldgaard, P., Kroon, M., Andreasson, E. & Bergvall, E. (2017). Ab initio and classical atomistic modelling of structure and defects in crystalline orthorhombic polyethylene: Twin boundaries, slip interfaces, and nature of barriers. Polymer, 121, 234-246
Öppna denna publikation i ny flik eller fönster >>Ab initio and classical atomistic modelling of structure and defects in crystalline orthorhombic polyethylene: Twin boundaries, slip interfaces, and nature of barriers
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2017 (Engelska)Ingår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 121, s. 234-246Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We study the stability of twin boundaries and slip in crystalline orthorhombic polyethylene by means of density functional theory (DFT), using a nonempirical, truly nonlocal density function, and by means of classical molecular dynamics (MD). The results show that, in accordance with experimental observations, there is a clear preference to chain slip over transverse slip for all considered slip planes. The activation energy for pure chain slip lies in the range 10–20 mJ/m2 while that for transverse slip corresponds to 40–280 mJ/m2. For the (11¯0)-slip plane the energy landscape is non-convex with multiple potential energy minima, indicating the presence of stable stacking faults. This suggests that dissociation of perfect dislocations into partials may occur. For the two low-energy twin boundaries considered in this work, {110} and {310}, we find that the former is more stable than the latter, with ground state energies corresponding to 8.9 and 28 mJ/m2, respectively. We have also evaluated how well the empirical MD simulations with the all-atom optimized potential for liquid MD simulations (OPLS-AA) and the coarse-grained united atom (UA) potential concur with the DFT results. It is found that an all-atom potential is necessary to partially capture the γ-surface energy landscapes obtained from the DFT calculations. The OPLS-AA predicts chain slip activation energies comparable with DFT data, while the transverse slip energy thresholds are low in comparison, which is attributed to weak close ranged monomer repulsion. Finally, we find that the H-H interaction dominates the slip activation. While not explicitly represented in the UA potential, its key role is revealed by correlating the DFT energy landscape with changes in the electron distributions and by MD simulations in which components of the OPLS-AA intermolecular potential are selectively silenced. © 2017 Elsevier Ltd

Ort, förlag, år, upplaga, sidor
Elsevier Ltd, 2017
Nyckelord
Atomistic modelling, Polyethylene, Slip, Atoms, Calculations, Chains, Chemical activation, Crystalline materials, Density functional theory, Molecular dynamics, Polyethylenes, Stacking faults, Classical molecular dynamics, Electron distributions, Ground-state energies, Intermolecular potentials, Nonlocal density-functions, Potential energy minima, Activation energy
Nationell ämneskategori
Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-14896 (URN)10.1016/j.polymer.2017.06.008 (DOI)000405747100026 ()2-s2.0-85021132061 (Scopus ID)
Tillgänglig från: 2017-07-06 Skapad: 2017-07-06 Senast uppdaterad: 2017-09-20Bibliografiskt granskad
Reheman, W., Ståhle, P., Andreasson, E. & Kao-Walter, S. (2017). NUMERICAL ANALYSIS OF ANISOTROPIC STIFFNESS OF THIN AL FOIL IN MULTIPLE MATERIAL DIRECTIONS BASED ON EXPERIMENTS. In: Jan Høgsberg and Niels L. Pedersen (Ed.), NSCM30 - the 30th Nordic Seminar on Computational Mechanics: Proceedings. Paper presented at 30th Nordic Seminar on Computational Mechanics (NSCM30), Copenhagen (pp. 175-178).
Öppna denna publikation i ny flik eller fönster >>NUMERICAL ANALYSIS OF ANISOTROPIC STIFFNESS OF THIN AL FOIL IN MULTIPLE MATERIAL DIRECTIONS BASED ON EXPERIMENTS
2017 (Engelska)Ingår i: NSCM30 - the 30th Nordic Seminar on Computational Mechanics: Proceedings / [ed] Jan Høgsberg and Niels L. Pedersen, 2017, s. 175-178Konferensbidrag, Publicerat paper (Refereegranskat)
Nyckelord
Thin foil, Aluminium alloy, Anisotropy, Symmetry plane, Young's modulus
Nationell ämneskategori
Annan maskinteknik
Identifikatorer
urn:nbn:se:bth-16371 (URN)
Konferens
30th Nordic Seminar on Computational Mechanics (NSCM30), Copenhagen
Tillgänglig från: 2018-06-08 Skapad: 2018-06-08 Senast uppdaterad: 2018-06-19Bibliografiskt granskad
Andreasson, E., Lindström, T., Käck, B., Malmberg, C. & Asp, A. M. (2017). Simulation of thin aluminium-foil in the packaging industry. In: Brabazon D.,Ul Ahad I.,Naher S. (Ed.), AIP Conference Proceedings: . Paper presented at 20th International ESAFORM Conference on Material Forming, ESAFORM,Dublin. American Institute of Physics Inc., 1896, Article ID 160014.
Öppna denna publikation i ny flik eller fönster >>Simulation of thin aluminium-foil in the packaging industry
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2017 (Engelska)Ingår i: AIP Conference Proceedings / [ed] Brabazon D.,Ul Ahad I.,Naher S., American Institute of Physics Inc. , 2017, Vol. 1896, artikel-id 160014Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

This work present an approach of how to account for the anisotropic mechanical material behaviour in the simulation models of the thin aluminium foil layer (≈10 μm) used in the Packaging Industry. Furthermore, the experimental results from uniaxial tensile tests are parameterised into an analytical expression and the slope of the hardening subsequently extended way beyond the experimental data points. This in order to accommodate the locally high stresses present in the experiments at the neck formation. An analytical expression, denominated Ramberg-Osgood, is used to describe the non-linear mechanical behaviour. Moreover it is possible with a direct method to translate the experimental uniaxial tensile test results into useful numerical material model parameters in Abaqus™. In addition to this the extended material behaviour including the plastic flow i.e. hardening, valid after onset of localisation, the described procedure can also capture the microscopic events, i.e. geometrical thinning, ongoing in the deformation of the aluminium foil. This method has earlier successfully been applied by Petri Mäkelä for paperboard material [1]. The engineering sound and parameterised description of the mechanical material behaviour facilitates an efficient categorisation of different aluminium foil alloys and aid the identification of the correct anisotropic (RD/TD/45°) mechanical material behaviour derived from the physical testing. © 2017 Author(s).

Ort, förlag, år, upplaga, sidor
American Institute of Physics Inc., 2017
Nationell ämneskategori
Annan maskinteknik Metallurgi och metalliska material
Identifikatorer
urn:nbn:se:bth-15679 (URN)10.1063/1.5008189 (DOI)000419825000232 ()2-s2.0-85037691878 (Scopus ID)9780735415805 (ISBN)
Konferens
20th International ESAFORM Conference on Material Forming, ESAFORM,Dublin
Tillgänglig från: 2017-12-21 Skapad: 2017-12-21 Senast uppdaterad: 2019-03-28Bibliografiskt granskad
Zhang, D., Mao, K., Islam, M. S. S., Andreasson, E. & Kao-Walter, S. (2016). Powerful Modelling Techniques in ABAQUS to Simulate Failure of Laminated composites. Karlskrona: Blekinge Tekniska Högskola
Öppna denna publikation i ny flik eller fönster >>Powerful Modelling Techniques in ABAQUS to Simulate Failure of Laminated composites
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2016 (Engelska)Rapport (Refereegranskat) [Forskning på konstnärlig grund]
Abstract [en]

In this study, laminated composites consisting of LDPE (Low Density Polyethylene), Al-foil (Aluminum foil)and an adhesive interface layer is focused. The defects like necking in LDPE, Al-foil layer and interfacial delaminationcan significantly impact the loading capacity of the laminated material. However, the influence mechanisms of thedefects are still unclear, and no appropriate research tool is available. Therefore, the FEM model based on alreadyavailable techniques in ABAQUS is developed in this work. The aim with the model is to create a robust numericalanalysis tool for further research work.In the modelling process, possibility of necking in substrates and interfacial delamination between material layers isconsidered. A coupled elasto-plasticity damage constitutive model, based on Hooke’s Law, the J2 yield criterion,isotropic hardening, associated flow-rule and ductile damage model, is formulated to demonstrate necking behaviorof substrates. In ABAQUS, three modelling techniques, namely VCCT, Cohesive Element, and XFEM, have been usedto simulate interfacial delamination. The simulation results are compared with the theoretical results.A uniaxial tension test consisting of a two material laminate is simulated by using these three modelling techniques.The special modelling skills for respective modelling techniques, element type, meshing technique of each model, arealso introduced. The comparison with the theoretical results shows necking in substrates and interfacial delaminationare also achieved in all three models as expected. Deformation results of the simulation are very close to that of thetheoretical analysis. Technique features of VCCT, Cohesive Element and XFEM in modelling of interfacialdelamination are analyzed and concluded. These three FEM models can all be utilized according to the requirementsof subsequent research.

Ort, förlag, år, upplaga, sidor
Karlskrona: Blekinge Tekniska Högskola, 2016. s. 9
Serie
Blekinge Institute of Technology Research report, ISSN 1103-1581 ; 2016:01
Nyckelord
Laminated Composites, Necking, Delamination, ABAQUS, Ductile Damage, VCCT, Cohesive Element, XFEM
Nationell ämneskategori
Teknisk mekanik
Identifikatorer
urn:nbn:se:bth-11934 (URN)
Projekt
KKs Profil MD3S
Forskningsfinansiär
KK-stiftelsen
Tillgänglig från: 2016-05-30 Skapad: 2016-05-30 Senast uppdaterad: 2016-08-17Bibliografiskt granskad
Zhang, D., Mao, K., Islam, M. S. S., Andreasson, E., Mehmood, N. & Kao-Walter, S. (2015). Powerful Modelling Techniques in Abaqus to Simulate Necking and Delamination of Laminated Composites.
Öppna denna publikation i ny flik eller fönster >>Powerful Modelling Techniques in Abaqus to Simulate Necking and Delamination of Laminated Composites
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2015 (Engelska)Övrigt (Övrigt vetenskapligt)
Abstract [en]

In this study, laminated composites consisting of LDPE (Low Density Polyethylene), Al-foil (Aluminum foil) and an adhesive interface layer is focused. The defects like necking in LDPE, Al-foil layer and interfacial delamination can significantly impact the loading capacity of the laminated material. However, the influence mechanisms of the defects are still unclear, and no appropriate research tool is available. Therefore, the FEM model based on already available techniques in ABAQUS is developed in this work. The aim with the model is to create a robust numerical analysis tool for further research work.

In the modeling process, possibility of necking in substrates and interfacial delamination between material layers is considered. The constitutive material behaviour is elastic-plastic complemented with progressive damage, based on Hooke’s Law, the J2 yield criterion, isotropic hardening, associated flow-rule and ductile damage model are formulated to demonstrate necking behavior of substrates. In ABAQUS, three modeling techniques, namely VCCT, Cohesive Element, and XFEM, have been used to simulate interfacial delamination. The simulation results are compared with the theoretical results.

A uniaxial tension test consisting of a two material laminate is simulated by using these three modeling techniques. The special modelling skills for respective modeling techniques, element type, meshing technique of each model, are also introduced. The comparison with the theoretical results shows necking in substrates and interfacial delamination are also achieved in all three models as expected. Deformation results of the simulation are very close to that of the theoretical analysis. Technique features of VCCT, Cohesive Element and XFEM in modelling of interfacial delamination are analyzed and concluded. These three FEM models can all be utilized according to the requirements of subsequent research.

Förlag
s. 21
Nyckelord
Laminated Composites, Necking, Delamination, ABAQUS, Ductile Damage, VCCT, Cohesive Element, XFEM
Nationell ämneskategori
Teknisk mekanik
Identifikatorer
urn:nbn:se:bth-11631 (URN)
Projekt
KKS profile MD3S
Anmärkning

This is a  presentation in SIMULIA 2015 Regional User Meeting, Copenhagen, Denmark, 12th October 2015

Tillgänglig från: 2016-02-12 Skapad: 2016-02-12 Senast uppdaterad: 2016-02-12Bibliografiskt granskad
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