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Larsson, Per-LennartORCID iD iconorcid.org/0000-0001-6232-8819
Alternative names
Publications (10 of 104) Show all publications
Staf, H., Olsson, E., Lindskog, P. & Larsson, P.-L. (2018). Determination of the Frictional Behavior at Compaction of Powder Materials Consisting of Spray-Dried Granules. Journal of materials engineering and performance (Print), 27(3), 1308-1317
Open this publication in new window or tab >>Determination of the Frictional Behavior at Compaction of Powder Materials Consisting of Spray-Dried Granules
2018 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 27, no 3, p. 1308-1317Article in journal (Refereed) Published
Abstract [en]

The frictional behavior during powder compaction and ejection is studied using an instrumented die with eight radial sensors. The average friction over the total powder pillar is used to determine a local friction coefficient at each sensor. By comparing forces at compaction with forces at ejection, it can be shown that the Coulomb's friction coefficient can be described as a function of normal pressure. Also stick phenomena has been investigated in order to assess its influence on the determination of the local friction coefficient.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Coulomb friction, cutting inserts, die friction, FEM, finite element simulations, granular powder, powder compaction, reverse engineering, stick, wall friction, WC-Co powder
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-224684 (URN)10.1007/s11665-018-3205-1 (DOI)000426701000041 ()2-s2.0-85042867461 (Scopus ID)
Note

QC 20180326

Available from: 2018-03-26 Created: 2018-03-26 Last updated: 2018-03-26Bibliographically approved
Fadil, H., Jelagin, D. & Larsson, P.-L. (2018). On the Measurement of two Independent Viscoelastic Functions with Instrumented Indentation Tests. Experimental mechanics, 58(2), 301-314
Open this publication in new window or tab >>On the Measurement of two Independent Viscoelastic Functions with Instrumented Indentation Tests
2018 (English)In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 58, no 2, p. 301-314Article in journal (Refereed) Published
Abstract [en]

In the present paper, a methodology for complete characterization of linear isotropic viscoelastic material with spherical instrumented indentation test is proposed. The developed method allows for measuring two independent viscoelastic functions, shear relaxation modulus and time-dependent Poisson's ratio, from the indentation test data obtained at non-decreasing loading, but otherwise arbitrary. Finite element modelling (FEM) is relied upon for validating the proposed methodology and for quantifying the influence of experimental variables on the measurements accuracy. Spherical indentation experiments are performed on several viscoelastic materials: polyoxymethylene, bitumen and bitumen-filler mastics. The viscoelastic material functions obtained with the indentation tests are compared with the corresponding results from the standard mechanical tests. Numerical and experimental results presented indicate that the methodology proposed allows mitigating the machine compliance and loading rate effects on the accuracy of the viscoelastic indentation tests.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Indentation, Viscoelasticity, Mechanics of materials, FEM, Bitumen, Bitumen-filler mastics
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-222406 (URN)10.1007/s11340-017-0342-7 (DOI)000423584800008 ()2-s2.0-85030833837 (Scopus ID)
Note

QC 20180228

Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2018-05-24Bibliographically approved
Larsson, P.-L. (2018). On the Variation of Hardness Due to Uniaxial and Equi-Biaxial Residual Surface Stresses at Elastic-Plastic Indentation. Paper presented at International Conference on Emerging Trends in Nanoscience and Nanotechnology (ICETINN), MAR 16-18, 2017, Sikkim Manipal Inst Technol, Majitar, INDIA. Journal of materials engineering and performance (Print), 27(6), 3168-3173
Open this publication in new window or tab >>On the Variation of Hardness Due to Uniaxial and Equi-Biaxial Residual Surface Stresses at Elastic-Plastic Indentation
2018 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 27, no 6, p. 3168-3173Article in journal (Refereed) Published
Abstract [en]

It is established long since that the material hardness is independent of residual stresses at predominantly plastic deformation close to the contact region at indentation. Recently though, it has been shown that when elastic and plastic deformations are of equal magnitude this invariance is lost. For materials such as ceramics and polymers, this will complicate residual stress determination but can also, if properly understood, provide additional important information for performing such a task. Indeed, when the residual stresses are equi-biaxial, the situation is quite well understood, but additional efforts have to be made to understand the mechanical behavior in other loading states. Presently therefore, the variation of hardness, due to residual stresses, is examined at a uniaxial stress state. Correlation with global indentation quantities is analyzed, discussed and compared to corresponding equi-biaxial results. Cone indentation of elastic-perfectly plastic materials is considered.

Place, publisher, year, edition, pages
SPRINGER, 2018
Keywords
correlation, equi-biaxial stresses, residual stresses, sharp indentation, uniaxial stresses
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-231719 (URN)10.1007/s11665-018-3393-8 (DOI)000435416000065 ()2-s2.0-85046654118 (Scopus ID)
Conference
International Conference on Emerging Trends in Nanoscience and Nanotechnology (ICETINN), MAR 16-18, 2017, Sikkim Manipal Inst Technol, Majitar, INDIA
Note

QC 20180817

Available from: 2018-08-17 Created: 2018-08-17 Last updated: 2018-11-13Bibliographically approved
Staf, H., Olsson, E., Lindskog, P. & Larsson, P.-L. (2017). On rate-dependence of hardmetal powder pressing of cutting inserts. Powder Metallurgy, 60(1), 7-14
Open this publication in new window or tab >>On rate-dependence of hardmetal powder pressing of cutting inserts
2017 (English)In: Powder Metallurgy, ISSN 0032-5899, E-ISSN 1743-2901, Vol. 60, no 1, p. 7-14Article in journal (Refereed) Published
Abstract [en]

The rate-dependence of hardmetal powder pressing in cutting insert production is investigated experimentally and numerically. In the latter case, the finite element method is relied upon using a continuum mechanics approach. In particular, possible rate-dependency due to creep deformation and rate-dependent friction is discussed with the experimental investigation focusing mainly on dimensional changes during sintering but also pressing forces. The results indicate that rate-dependent frictional effects are the dominating feature and accordingly, it can be argued that for the metal powders investigated here, creep deformations do not have to be accounted for in the constitutive description at the timescales relevant for powder pressing and when the shape after sintering is concerned. For the present powder, the apparent frictional effect decreases at higher pressing rates. Additional details of the friction behavior are studied comparing finite element simulations with experiments.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2017
Keywords
Rate-dependence, powder compaction, friction, creep, WC-Co powder, cutting inserts, material model, finite element simulations
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-205172 (URN)10.1080/00325899.2016.1260904 (DOI)000396619000003 ()2-s2.0-85007143910 (Scopus ID)
Note

QC 20170411

Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2017-06-29Bibliographically approved
Larsson, P.-L. (2017). On the Influence of Elastic Deformation for Residual Stress Determination by Sharp Indentation Testing. Journal of materials engineering and performance (Print), 26(8), 3854-3860
Open this publication in new window or tab >>On the Influence of Elastic Deformation for Residual Stress Determination by Sharp Indentation Testing
2017 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 26, no 8, p. 3854-3860Article in journal (Refereed) Published
Abstract [en]

The determination of residual stresses in engineering materials using sharp indentation testing is studied analytically and numerically. The numerical part of the investigation is based on the finite element method. In particular, the effect from elastic deformations on global indentation properties is discussed in detail. This effect is essential when residual stresses are to be determined based on the change of the contact area due to such stresses. However, standard relations for this purpose are founded on the fact that the material hardness is invariant as regards residual (applied) stresses. Presently, this assumption is scrutinized and it is shown that it is only valid at dominating plastic deformation around the contact region. The hardness dependence of residual stresses can, however, be correlated in the same way as in the case of stress-free materials, indicating that the wealth of characterization formulas pertinent to indentation hardness is available also for the purpose of residual field determination. Only cone indentation of elastic-perfectly plastic materials is considered, but the generality of the results is discussed in some detail.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
elastic deformations, hardness values, residual stresses, sharp indentation
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-214345 (URN)10.1007/s11665-017-2816-2 (DOI)000407994400024 ()2-s2.0-85021998112 (Scopus ID)
Note

QC 20170912

Available from: 2017-09-12 Created: 2017-09-12 Last updated: 2017-11-10Bibliographically approved
Weddfelt, K., Saadati, M. & Larsson, P.-L. (2017). On the load capacity and fracture mechanism of hard rocks at indentation loading. International Journal of Rock Mechanics And Mining Sciences, 100, 170-176
Open this publication in new window or tab >>On the load capacity and fracture mechanism of hard rocks at indentation loading
2017 (English)In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 100, p. 170-176Article in journal (Refereed) Published
Abstract [en]

The load capacity of selected hard rocks subjected to circular flat punch indentation is investigated. The compacted zone underneath the indenter is assumed to be limited and only responsible for the load transition to the rest of the material. Therefore, the theory of elasticity is used to define the stress state in a semi-infinite medium loaded by a flat punch indenter. The final load capacity is related to the formation of a sub-surface median crack that initiates due to tensile hoop (circumferential) stresses. Therefore the final failure should occur at a force level in which the hoop stress is greater than the tensile strength of the rock. Since the tensile stress is distributed over a volume of material, tensile crack failure can occur at different locations with tensile hoop stress depending on where the most critical flaw is located. Therefore, the initiation of the median crack that should be responsible for the final load capacity is treated as a probabilistic phenomenon. This process is described by Weibull theory which will be used as a failure criterion. It is assumed here that the opening of median crack triggers a final violent rupture, therefore the assumption in Weibull theory, that the final failure occurs as soon as a macroscopic fracture initiates from a microcrack is fulfilled. The effective volume is calculated for a semiinfinite medium loaded by a flat punch indenter. The material properties of Bohus granite obtained from three point bending tests are used as reference values in describing the Weibull size effect. The experimental results for the stamp load capacity of three selected hard rocks are taken from the literature. They are considered similar rocks to the reference material in this paper, which is Bohus granite. The model describes the observed load capacity with a very good accuracy for all three rocks. It is likely that the presently proposed methodology is applicable for other types of semi-brittle materials and indenter shapes.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-220606 (URN)10.1016/j.ijrmms.2017.10.001 (DOI)000418009400017 ()2-s2.0-85033561320 (Scopus ID)
Note

QC 20180115

Available from: 2018-01-15 Created: 2018-01-15 Last updated: 2018-01-15Bibliographically approved
Larsson, P.-L. & Olsson, E. (2017). Plastic zone size at sharp indentation contact of classical elastic-plastic materials: Behavior at linear strain hardening. Journal of Testing and Evaluation, 45(5)
Open this publication in new window or tab >>Plastic zone size at sharp indentation contact of classical elastic-plastic materials: Behavior at linear strain hardening
2017 (English)In: Journal of Testing and Evaluation, ISSN 0090-3973, E-ISSN 1945-7553, Vol. 45, no 5Article in journal (Refereed) Published
Abstract [en]

The present analysis concerns a finite-element study of sharp (cone) indentation of classical elastic-plastic materials with linear strain hardening and, especially, the details of the behavior of the size of the plastic zone are at issue. It is shown that the plastic zone size parameters are dependent on two parameters: the well-known Johnson parameter and the level of plastic hardening. This dependence includes both geometrical and material properties. The details of the influence from the hardening level have not been explicitly studied previously. The results are compared with previous findings for elastic-ideally plastic materials.

Place, publisher, year, edition, pages
ASTM International, 2017
Keywords
Correlation, Hardness, Indentation testing, Plastic zone, Correlation methods, Finite element method, Hardening, Plastics, Strain hardening, Thermoelectricity, Elastic ideally plastic materials, Elastic-plastic Material, Finite-element study, Plastic hardening, Plastic zone size, Plastic zones, Sharp indentation, Elastoplasticity
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-216562 (URN)10.1520/JTE20160140 (DOI)000419815300033 ()2-s2.0-85029157162 (Scopus ID)
Note

QC 20171108

Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2018-01-29Bibliographically approved
Olsson, E. & Larsson, P.-L. (2016). A unified model for the contact behaviour between equal and dissimilar elastic-plastic spherical bodies. International Journal of Solids and Structures, 81, 23-32
Open this publication in new window or tab >>A unified model for the contact behaviour between equal and dissimilar elastic-plastic spherical bodies
2016 (English)In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 81, p. 23-32Article in journal (Refereed) Published
Abstract [en]

A unified method for calculating the contact force and the contact area between two dissimilar elastic-plastic spheres is presented with the aim of simulating granular materials using particle methods. Explicit equations are presented for the case when the plastic behaviour of the spheres is described with three material parameters. This makes the analysis applicable for a wide range of materials. The model is partly based on dimensionless quantities emerging from the Brinell hardness test. Large deformation of the contact is accounted for in the analysis, which allows for accurate contact relations up to indentation depths relevant for powder compaction. The presented model shows excellent agreement with finite element simulations of two spheres in contact and the results found in literature. An implementation of the contact model in Python is provided together with the online version of this paper.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Contact mechanics, Force-displacement relations, Elastic-plastic material, Large deformations, Discrete element method
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-183306 (URN)10.1016/j.ijsolstr.2015.10.004 (DOI)000370089200003 ()2-s2.0-84956688028 (Scopus ID)
Note

QC 20160309

Available from: 2016-03-09 Created: 2016-03-07 Last updated: 2017-11-30Bibliographically approved
Larsson, P.-L. (2016). Correlation of global quantities for material characterization by sharp indentation testing of elastoplastic materials. Journal of Testing and Evaluation, 44(6), 2293-2301
Open this publication in new window or tab >>Correlation of global quantities for material characterization by sharp indentation testing of elastoplastic materials
2016 (English)In: Journal of Testing and Evaluation, ISSN 0090-3973, E-ISSN 1945-7553, Vol. 44, no 6, p. 2293-2301Article in journal (Refereed) Published
Abstract [en]

Indentation problems pertinent to sharp indenters were examined. The analysis concerned classical elastic-plastic materials and, especially so, the details of the behavior of global contact quantities, such as mean contact pressure and the size of the contact area, in the transition region where elastic and plastic effects are of equal magnitude. The global contact quantities were correlated accurately using a single parameter, comprising both geometrical and mechanical properties, and presented using closed form expressions directly applicable to material characterization or measurements of residual mechanical fields by sharp indentation tests, but also for situations such as contact in gears or in electronic devices. The derived relations were based on highly accurate previous results from finite element studies of sharp indentation problems.

Place, publisher, year, edition, pages
ASTM International, 2016
Keywords
Elastoplastic materials, Hardness, Indentation correlation, Level II indentation, Relative contact area, Elastoplasticity, Materials testing, Closed-form expression, Contact areas, Elastic-plastic Material, Finite-element study, Material characterizations, Mean contact pressure, Transition regions, Characterization
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-201994 (URN)10.1520/JTE20150011 (DOI)000402374600023 ()2-s2.0-85002252464 (Scopus ID)
Note

QC 20170303

Available from: 2017-03-03 Created: 2017-03-03 Last updated: 2017-06-15Bibliographically approved
Larsson, P. L. & Olsson, E. (2016). Elastic-plastic contact between hard metal particles. In: Key Engineering Materials: (pp. 86-99).
Open this publication in new window or tab >>Elastic-plastic contact between hard metal particles
2016 (English)In: Key Engineering Materials, 2016, p. 86-99Conference paper, Published paper (Refereed)
Abstract [en]

In the present study contact between elastic-plastic dissimilar spherical particles are investigated. The investigation is based on analytical and numerical methods and in the latter case in particular the finite element method. The results presented are pertinent to force-displacement relations at contact when elastic and plastic deformations are of equal magnitude. Especially, hard metal particles are considered with a typical application area being analysis of powder compaction.

Keywords
Contact mechanics, Elastic-plastic deformation, Force-displacement relations, Hard metals, Spherical particles
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-186764 (URN)10.4028/www.scientific.net/KEM.681.86 (DOI)2-s2.0-84959543060 (Scopus ID)
Note

QC 20160530

Available from: 2016-05-30 Created: 2016-05-13 Last updated: 2016-05-30Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6232-8819

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