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This paper aims to first apply more advanced anisotropic yield criterions as Yld91 and Yld2004 to spherical indentation simulations, and investigate plastic anisotropy identified from indentation simulations following different yield criterions (Hill48, Yld91, Yld2004) to discover laws. It also aims to compare the difference in plastic anisotropy identified from indentation on three yield criterions and evaluate the applicability of plastic anisotropy.

This paper uses indentation simulations on different yield criterions to identify plastic anisotropy. First, the trust-region techniques based on the nonlinear least-squares method are used to determine anisotropy coefficients of Yld91 and Yld2004. Then, Yld91 and Yld2004 are implemented into ABAQUS software using user-defined material (UMAT) subroutines with the proposed universal structure. Finally, through considering comprehensively the key factors, the locations of the optimal data acquisition points in indentation simulations on different yield criterions are determined. And, the identified stress–strain curves are compared with experimental data.

This paper discovers that indentation on Yld2004 is able to fully identify difference in equivalent plastic strain between 0° and 90° directions when indentation depth h_t is relatively smaller. And, this research demonstrates conclusively that plastic anisotropy identified from indentation on Yld2004 and Yld91 is more applicable at larger strains than that on Hill48, and that on Yld2004 is more applicable than that on Yld91, overall. In addition, the method on the determination of the locations of the optimal data acquisition points is demonstrated to be also valid for anisotropic material.

This paper first investigates plastic anisotropic properties and laws identified from indentation simulations following more advanced anisotropic yield criterions and provides reference for later research.

The purpose of this paper is to investigate the use of nanoindentation with a Berkovich indenter as a method of extracting equivalent stress‐strain curves for the base metal and the welded zone of a friction stir welded aluminum alloy.

Friction stir welding is a solid‐state joining process, which emerged as an alternative technique to be used in high strength alloys that were difficult to join with conventional joining techniques. This technique has a significant effect on the local microstructure and residual stresses combined with deformation. Nano‐ and micro‐indentation are the most commonly used techniques to obtain local mechanical properties of engineering materials. In order to test the reliability of nanoindentation technique and to connect nanoscale with macroscale, the indentation hardness‐depth relation established by Nix and Gao was applied on the experimental values.

The predictions of this model were found to be in good agreement with classical hardness measurements on AA 6082‐T6 aluminum alloy. Also, finite element method provides a numerical tool to calculate complex nanoindentation problems and in correlation with gradients theories forms a well‐seried tool in order to take into account size effects.

By studying this alloy, the paper reviews fundamental principles such as stress‐strain distribution, size effects rise during nanoindentation and the applicability of finite element method, in order to take into account these issues.

This paper gives a bibliographical review of the finite element modelling and simulation of indentation testing from the theoretical as well as practical points of view. The bibliography lists references to papers, conference proceedings and theses/dissertations that were published between 1990 and 2002. At the end of this paper, 509 references are listed dealing with subjects such as, fundamental relations and modelling in indentation testing, identification of mechanical properties for specific materials, fracture mechanics problems in indentation, scaling relationship for indentation, indenter geometry and indentation testing.

Indentation tests performed in creep damage materials show that slopes of initial portions of unloading curves which are often used to calculate indented modulus can characterize creep damage. To evaluate the influence of different indenters in determining creep damage, conical, spherical and cylindrical indenters which are all self‐similar in shape were considered by using the Finite Element Method (FEM). Indentation load (P)‐displacement (h) curves and equivalent elastic modulus ( E * )‐creep damage (ω) curves were given. Results show that the cylindrical indenter is appropriate for “soft” materials, the conical indenter is suitable for small creep damage materials, and the spherical indenter can be used in many other materials.

Sliding wear is a common phenomenon in the iron ore handling industry. Large-scale handling of iron ore bulk-solids causes a high amount of volume loss from the surfaces of bulk-solids-handling equipment. Predicting the sliding wear volume from equipment surfaces is beneficial for efficient maintenance of worn equipment. Recently, the discrete element method (DEM) simulations have been utilised to predict the wear by bulk-solids. However, the sensitivity of wear prediction subjected to DEM parameters has not been systemically investigated at single particle level. To ensure the wear predictions by DEM are accurate and stable, this study aims to conduct the sensitivity analysis at the single particle level.

In this research, pin-on-disc wear tests are modelled to predict the sliding wear by individual iron ore particles. The Hertz–Mindlin (no slip) contact model is implemented to simulate interactions between particle (pin) and geometry (disc). To quantify the wear from geometry surface, a sliding wear equation derived from Archard’s wear model is adopted in the DEM simulations. The accuracy of the pin-on-disc wear test simulation is assessed by comparing the predicted wear volume with that of the theoretical calculation. The stability is evaluated by repetitive tests of a reference case. At the steady-state wear, the sensitivity analysis is done by predicting sliding wear volumes using the parameter values determined by iron ore-handling conditions. This research is carried out using the software EDEM^® 2.7.1.

Numerical errors occur when a particle passes a joint side of geometry meshes. However, this influence is negligible compared to total wear volume of a wear revolution. A reference case study demonstrates that accurate and stable results of sliding wear volume can be achieved. For the sliding wear at steady state, increasing particle density or radius causes more wear, whereas, by contrast, particle Poisson’s ratio, particle shear modulus, geometry mesh size, rotating speed, coefficient of restitution and time step have no impact on wear volume. As expected, increasing indentation force results in a proportional increase. For maintaining wear characteristic and reducing simulation time, the geometry mesh size is recommended. To further reduce simulation time, it is inappropriate using lower particle shear modulus. However, the maximum time step can be increased to 187% T_R without compromising simulation accuracy.

The applied coefficient of sliding wear is determined based on theoretical and experimental studies of a spherical head of iron ore particle. To predict realistic volume loss in the iron ore-handling industry, this coefficient should be experimentally determined by taking into account the non-spherical shapes of iron ore particles.

The effects of DEM parameters on sliding wear are revealed, enabling the selections of adequate values to predict sliding wear in the iron ore-handling industry.

The accuracy and stability to predict sliding wear by using EDEM^® 2.7.1 are verified. Besides, this research accelerates the calibration of sliding wear prediction by DEM.

Diamond‐like carbon coatings (DLC) combine high wear resistance with low friction coefficients. Both properties enable the protective layers to sustain wide ranges of loading and environmental conditions. At present, low friction coatings are commonly used on an empirical basis but not as a design element. The reason for the empirical approach is the lack of tools for a description of the interaction between the coatings and the substrate. Furthermore it is difficult to obtain information on the fracture properties of the coating substrate system (e.g. fracture toughness, adhesion, residual stresses). A spherical indentation provides a simple technique to measure quantitatively the fracture toughness and the adhesion of brittle coatings on a ductile substrate with standard laboratory equipment. DLC coatings on a 100 Cr 6 steel substrate are indented by silicon nitride balls with different diameters and different loads. Fracture patterns (circular and radial cracks, delamination) are analyzed by finite element calculation and the fracture toughness of the coating itself along with the interface toughness are estimated.

The purpose of this paper is to establish a law on the durability of thick aluminium wire bonds in low cycle fatigue for different geometries and wire diameters under a purely mechanical load.

Bond wires with different geometries were tested with various loads and a mechanical test bench, and their endurance was determined. The same load situation was modelled with finite element analysis and then compared against the experimental results.

A correlation was found between the plastic strain per cycle and the determined lifespan. Therefore, the lifespan can be calculated by mechanical‐plastic simulation for various loop geometries and loading cases.

The loop height strongly influences the durability of the wire bond, whereas other parameters, such as the loop angle, have a weaker influence on the bond heel lifetime.

The mechanical simulation is able to replace the time‐consuming lifetime experiments.

This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1977‐1998. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, ferrites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

The purpose of this paper is to determine if the nanoindentation technique is a reliable method and whether it can be used to measure the surface hardness (H) in friction stir welded aluminum alloys. In order to test the reliability of nanoindentation technique, nanohardness values for friction stir welded aluminum alloys were compared to microhardness values. Additionally, the onset of plasticity (yielding) is investigated.

Nanoindentation experiments were performed for the determination of onset on plasticity (yielding) and comparison of local mechanical properties of both welded alloys. In order to test the reliability of nanoindentation technique, nanohardness values for friction stir welded AA6082 were compared to microhardness values. The specimen was tested using two different instruments – a Vickers microhardness tester and a nanoindenter tester for fine scale evaluation of H.

The results of this study indicate that nanohardness values with a Berkovich indenter reliably correlate with Vickers microhardness values. Nanoindentation technique can provide reliable results for analyzing friction stir welded aluminum alloys. The welding process definitely affects the material mechanical properties.

Microhardness and nanohardness obtained values can be correlated carefully, regarding the similarities and the differences of the two above mentioned techniques.

The indentation behaviour of sandwich panels is significant to incipient damage and is known to be affected by a number of dominant parameters. However, it is challenging not only to demonstrate how those few dominant parameters influence the indentation behaviour but also to ascertain that such influence was coupled to the variation of the other dominant parameters. The paper aims to discuss these issues.

In this work, the authors adopted a controllable quasi-static testing to carry out a diagnostic interrogation on the nature of incipient damage in laminate-skinned sandwich panels using hemispherical indenter and used photographs taken from the cross-sections of all the cut-up tested specimens, which were stopped both just before and after the initial critical loads, respectively, to confirm the mechanism of the incipient damage. Sandwich panels with aluminium honeycomb core had carbon/epoxy skins of two different thicknesses and lay-ups and hemispherical nosed indenter had three different diameters.

The authors found that: the incipient damage mechanism in all the panels was combined delamination in the skin and core crushing without debonding; doubling the skin thickness had the significant enhancement on critical load and indentation and this enhancement became greater for the larger indenter diameters; the indenter diameter had the moderate effect on critical load in the thick panels from 8 to 14 mm but had the negligible effect on thin panels and no effect on the thick panels from 14 to 20 mm; varying the skin lay-up or support had little effect on the indentation behaviour.

These findings were limited to the constant core density and core thickness. Varying the former significantly could alter the findings accordingly.

The results of this work should be tremendously useful to design and analysis in industrial applications of sandwich structures in aircraft, vehicles, marine vessels and transport carriages for situations involving localised loading and deformation.

The results of this research work is one of the very few that demonstrated a systematic understanding of the indentation behaviour characteristics of sandwich construction, which is vital to the establishment of indentation law for sandwich structures in future.