In this paper, a methodology, for calculating the stress level of monotonic plastically pre-hardened materials, using the instrumented indentation technique (IIT) coupled to the inverse analysis technique (IAT) is presented. In this methodology, the Voce work-hardening law is always considered as the work hardening law of the studied material. This methodology has shown a very good efficiency in determining the stress levels and the plastic strains undergone by two pre-hardened pseudo-materials. That was encouraging for applying this methodology on real metal sheets. Three metal sheets were studied (DC01 and DP600 steels and aluminum alloy 2017). In the case of the as-received sheets, the identified laws show precise results for plastic strains between 3% and 6% which correspond approximately to the representative strain in the case of spherical indentation. Tensile samples were then pre-hardened by imposing a monotonic plastic strain. Three levels of plastic pre-strains were imposed. Concerning low pre-hardening levels, very satisfying results were obtained where this methodology showed a great efficiency in determining the stress level and the plastic pre-strain undergone by the pre-hardened sheet. For high pre-hardening levels, a small underestimation of the stress level and the plastic pre-strain was obtained. In this latter case, work is being carried out to improve the results by enriching the experimental data provided for the inverse analysis computations.

BackgroundThe progress in information and communication technology (ICT) led to the development of a new rehabilitation technique called “serious game for functional rehabilitation.” Previous works have shown that serious games can be used for general health and specific disease management. However, there is still lack of consensus on development and evaluation guidelines. It is important to note that the game performance depends on the designed scenario.ObjectiveThe objective of this work was to develop specific game scenarios and evaluate them with a panel of musculoskeletal patients to propose game development and evaluation guidelines.MethodsA two-stage workflow was proposed using determinant framework. The development guideline includes the selection of three-dimensional (3D) computer graphics technologies and tools, the modeling of physical aspects, the design of rehabilitation scenarios, and the implementation of the proposed scenarios. The evaluation guideline consists of the definition of evaluation metrics, the execution of the evaluation campaign, the analysis of user results and feedbacks, and the improvement of the designed game.ResultsThe case study for musculoskeletal disorders on the healthy control and patient groups showed the usefulness of these guidelines and associated games. All participants enjoyed the 2 developed games (football and object manipulation), and found them challenging and amusing. In particular, some healthy subjects increased their score when enhancing the level of difficulty. Furthermore, there were no risks and accidents associated with the execution of these games.ConclusionsIt is expected that with the proven effectiveness of the proposed guidelines and associated games, this new rehabilitation game may be translated into clinical routine practice for the benefit of patients with musculoskeletal disorders.

International audienceElastic modulus of a large variety of materials: low-carbon steel, rolled and rapid prototyping stainless steels, aluminum, brass, beta tricalcium phosphate (β-TCP) bioceramic and the TiB2–60% B4C composite ceramic were determined by Vickers instrumented indentation tests. A relationship the ratio of elastic recovery energy to total work-of-indentation and the product of the maximum applied load and the square of the contact stiffness is proposed to assess the elastic modulus of materials. A proportionality factor κ defining pile-up or sink-in behavior has been validated by both the Finite Element (FE) analysis and inverse method for a material presenting an intermediate mechanical behavior. Values obtained for elastic modulus agree satisfactorily with theoretical values found in literature. The main advantage of the proposed relationship in the determination of the elastic modulus is that it does not require the computation of the contact area between the indenter and the material which is often at the origin of uncertainties

This paper is a phenomenological study representing the influence of the hardening type on the instrumented indentation F-h curve. Spherical instrumented indentation and inverse analysis techniques (IAT) are used and two metallic materials (DP600 and AA2017) are investigated. Pure isotropic (Voce) and combined (Chaboche 1986) hardening laws are adopted for describing the plastic behavior of the studied materials. The influence of the hardening type on the indentation loading curve is studied first. Kinematic hardening results in softening the indentation loading curve. This is due to some regions in the indented zone that undergo different loading paths during loading. Hardenin g types (kinematic & isotropic) should be considered to accurately characterize the mechanical behaviour of different metallic materials using indentation curves. The influence of the hardening type on the indentation unloadingreloading curve (hysteresis loop) is then studied. Kinematic hardening has an important influence on the hysteresis loop. This influence has been investigated closely and a methodology is proposed for estimating the contribution of each hardening type in the overall hardening behavio r. This methodology is based on geometrical parameters directly influenced by the hardening type and presents great potential if considered in future works aiming to identify parameters of relatively complex hardening laws using the instrumented indentation technique (IIT).

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