Formulation method of ball indentation process for ultra-thin elastic body with mechanics poisson effect

A new theoretical method for determining the mechanics properties of ultra-thin elastic materials is proposed in this paper. This method is based on a full contact model and Poisson’s effect. This study consisted of three steps. First, FE model of indentation problem for ultra-thin specimen is developed by elastic constitutive relationship for precise analysis of problem. Second, the simplified model is used to evaluate the result of FEM, and its availability is discussed by comparison with extended Hertzian theory. Third, an equation is proposed after comparing the results of FEM, extended Hertzian theory and full contact model

Numerical evaluation of wearing pressure and cloth stiffness on vibration of human skeletal muscle during athletic movement

In the design of sportswear which is expected to modify the performance of athletes, it is important to clarify the effects of the wear's rigidity and wearing pressure on the vibrations during exercise because they have been considered to reduce the vibrations of muscles. Therefore, in this study, the relationship between the vibration generated in cyclic movement of thigh with cloth and the physical properties of the wearing cloth is discussed by using a simple FE model of thigh [1, 2]. In the analysis, the FE model consisted of three parts of the thigh muscle, the femur, and the wear in the cross section of thigh. The thigh muscle is fixed to the femur but it is in contact with the wear cloth ignoring friction. The condition of the thigh cyclical movement is set assuming the athlete's 100 m run. Numerical analysis is performed under these conditions, and the variations of vibration behavior due to changing values of muscle, wear and pressure are evaluated by mechanical consideration. In the results of this FE analysis, it is quantitatively confirmed that more flexible cloth has the effect of restraining vibration, and also its effect can also be observed by applying wearing pressure to thigh

The elastoplasticity behavior of wire in inhomogeneous woven metal mesh

This paper discusses the plastic behavior of wires in metal mesh for discussing the structure of woven warp and weft with their inhomogeneous and homogeneous by using finite element method (FEM). In the FEM, an isotropic plasticity is adopted as constitutive model of woven wire, but inhomogeneous between warp and weft is discussed to evaluate the mechanical characteristic of the mesh as an industrial products. Here, fundamental relation of power law hardening rule is adopted to represent the plasticity, but physical parameters of it will be controlled for the discussion of plasticity on mesh weaving. The inhomogeneous of mesh structure is one of key technology to control the product quality of metal mesh, and the mechanics of plasticity of metal mesh should be discussed to develop the product. In this report, the difference of material parameters and tension during weaving process is targeted on the discussion. Some conditions on the wires of warp and weft are examined in weaving process by FE

Compression behaviors of low-density porous materials under multiaxial stress conditions

In this study, uniaxial and multiaxial compression tests are conducted for studying the nonlinear deformation behaviors of a porous material during compression. In the results of uniaxial compression tests, the stress level in the plateau region is varied by the difference of direction but it is shown that this material has the character of transverse isotropicity. The multiaxial behavior of the material is also observed in this study. Equibiaxial pre-strained compression tests are adopted for the observation of the characteristics of the material. The results of these tests show that the pre-strain causes the porous material to harden, and the extent of the hardening depends on the difference of the amount of pre-strain

Highly accurate spatial mode generation using spatial cross modulation method for mode division multiplexing

We propose a spatial mode generation technology using spatial cross modulation (SCM) for mode division multiplexing (MDM). The most well-known method for generating arbitrary complex amplitude fields is to display an off-axis computer-generated hologram (CGH) on a spatial light modulator (SLM). However, in this method, a desired complex amplitude field is obtained with first order diffraction light. This critically lowers the light utilization efficiency. On the other hand, in the SCM, the desired complex field is provided with zeroth order diffraction light. For this reason, our technology can generate spatial modes with large light utilization efficiency in addition to high accuracy. In this study, first, a numerical simulation was performed to verify that the SCM is applicable for spatial mode generation. Next, we made a comparison from two view points of the coupling efficiency and the light utilization between our technology and the technology using an off-axis amplitude hologram as a representative complex amplitude generation method. The simulation results showed that our technology can achieve considerably high light utilization efficiency while maintaining the enough coupling efficiency comparable to the technology using an off-axis amplitude hologram. Finally, we performed an experiment on spatial modes generation using the SCM. Experimental results showed that our technology has the great potential to realize the spatial mode generation with high accuracy

BEHAVIOR EVALUATION OF DEFORMATION, DAMAGE AND FRACTURE OF BIOLOGICAL SOFT TISSUE BY USING INDENTATION TEST

ABSTRACT In this study, two types of indentation tests were used for the observation of deformation behavior of biological soft tissue, because indentation testing is an easy method to manage observation and control of the condition of complex tissue specimens. First, a fundamental indentation test was used to evaluate quasi-static deformation behavior of soft tissue. In the evaluation of the quasi-static behavior, elasticity, damage, and fracture of the tissue were analyzed from the profile of reaction force during the indentation. Ball-impact testing with subsonic indentation velocity was used for the evaluation of dynamic behaviors of soft tissue. In the impact test, the viscoelastic characteristics of specimens were evaluated by analyzing stress response, using extended Hertzian contact theory and wave equations, at the moment when a simple ball bullet shot from an airsoft gun strikes the specimen. In the experimental results of the test, an obvious relationship between quasi-static and impact responses of the specimen were observed subjectively. The results are evaluated to analyze the damage and the fracture of the soft tissue for the objective formulation of tissue mechanics. The plateau behavior of reaction force in relation to stress response was also reviewed, in order to quantify the beginning of tissue fracture

Two Cases of Severe Degeneration of the Macula Following Vitrectomy with Indocyanine Green-Assisted Internal Limiting Membrane Peeling for Idiopathic Macular Hole

We describe three eyes of two cases of severe degeneration of the macula following vitrectomy with indocyanine green-assisted internal limiting membrane peeling for idiopathic macular hole. We need to remember the possibility of these complications and have to select the procedures that are safest to use for macular hole surgery

Radiative recombination of excitons in disk-shaped InAs/InP quantum dots

Recombination dynamics of excitons confined in disk-shaped InAs/InP quantum dots is studied by time-resolved photoluminescence measurements. By comparing the result with that in a homologous ultrathin quantum well, it is revealed that the lateral confinement of excitons suppresses the thermal variation of the radiative recombination lifetime. The oscillator strength of the radiative transition is reduced with the decrease of the disk height, which is attributed to the increasing tunneling into the InP barrier of the exciton wave function

Theoretical and Experimental Studies on Thermal Properties of Polyester Nonwoven Fibrous Material

Polyester nonwoven fibrous material is widely used in construction and automobile industries for thermal insulation purposes. It is worthy and meaningful to understand the effect of structural parameters on the thermal property. Fiber orientation, as one of the most vital parameters, has a significant effect on thermal property. However, there has been little quantitative analysis focusing on this aspect. This paper theoretically and experimentally analyzes the thermal conductivity of samples with varying fiber orientation. Existing models were selected to predict the thermal conductivity of polyester nonwoven samples. Two different apparatus were applied to carry out the experimental measurements. The relative differences between the predicted and measured results were compared. One commonly used model was modified for accurate prediction. It was shown that some existing models under- or overestimate the thermal conductivity compared to the measured values. The results indicate that the modified model can accurately predict the thermal conductivity of polyester nonwoven materials within a 0.2% relative difference