Measurement Of Elastic Deformation Research Articles

Validation of an electro-hydraulic press for dynamic measurement of elastic deformations in agricultural tires

Tests with agricultural tires and wheelsets allow for mitigating the machinery traffic limitations to crop productivity, as it shows the tire-surface interaction under different suitability conditions, optimizing farming processes with the use of technology. Thus, this paper aims to develop an electro-hydraulic press for dynamically measuring elastic deformations occurring in agricultural tires. The experiment used a completely randomized design, evaluating two pneumatic wheelsets, bias-ply and radial, and six vertical loads, 4.9033, 9.8066, 14.71, 19.6133, 24.5166, and 29.4199 kN, on the tire, totalizing 12 treatments with five repetitions. The analyzed parameters are contact area, horizontal and vertical deflection. The collected data underwent an analysis of variance F-test and a polynomial regression analysis. The results showed continuous replicability of the data obtained with the electro-hydraulic press. That demonstrates the efficiency of the developed device for evaluating agricultural tires in a controlled environment. The bias-ply tire presented a smaller contact area than the radial with the increase of incident loads, and the 14.71 kN load achieved a higher amplitude, generating a difference of 40 %. The maximum load resulted in 27 % more horizontal deflections for the radial tire. However, the vertical deflection values were 8 % higher with the bias-ply tires.

An elastic–viscoplastic model with non-affine deformation and rotation of a distribution of embedded fibres

A large deformation continuum model for an elastically isotropic visco-plastic matrix reinforced by a distribution of fibres has been formulated. The fibre distribution is a symmetric positive-definite tensor with unit trace that is determined by an evolution equation. This evolution equation includes a competition between tendencies for affine evolution of the distribution and non-affine evolution causing the distribution to align with the elastic distortional deformation tensor or to become isotropic. Two elastic deformation measures are introduced associated with the fibre distribution. Specifically, non-affine measures of elastic distribution stretch and non-coaxiality of the distribution cause anisotropic stress response. The resulting model describes a number of effects relevant to growth and remodelling of biological tissues as well as to additive manufacturing of artificial materials. For example, the equations model the smooth transition from isotropic to anisotropic response seen in many biological tissues.

Geomechanical analysis of location and conditions for mining-induced tremors in LGOM copper mines

This paper presents the results of the statistical analyses of rock mass seismicity associated with O/ZG Rudna exploitation and geomechanical analyses concerning the location and conditions of tremor occurrences in LGOM conditions, illustrated by the example of O/ZG Rudna. As part of the statistical analyses, the assessment of rock mass seismicity formation in O/ZG Rudna throughout the whole mine area in the years 2006–2015 is presented, the results of which were the basis for subsequent geo-mechanical analyses. Within the parameters of seismic activity, the analysis covered the number of recorded events, the total value of energy emission and the index of individual energy expenditure. The presented analyses also refer to the locations of tremor source epicentres in relation to the exploitation front, distinguished into low energy and high energy tremors located ahead of the exploitation front, in the area of opening-up works and gobs. These recent results were the starting point for research and calculations on geo-mechanical analyses. These numerical calculations using the finite element method (FEM) carried out the energy density distribution of elastic deformation in the vicinity of the exploitation front. FEM calculations were designed to establish the factors and conditions that determine the location of tremor sources and the mechanism of rock destruction. Both of these factors are directly related to the magnitude of the energy emitted during the tremor. Appropriate energy measurements of elastic deformation have been adopted to determine rock mass areas which are potentially threatened by tremor occurrences of varying energy. Measures of the energy density of shear and volumetric strain enable the determination of the nature of rock mass destruction in the vicinity of mine workings, which in turn gives the basis for linking these measurements with tremor energy and location relative to the exploitation front. The results of numerical computations were compared with the results of statistical analyses on the locations of tremor sources with different energies in relation to the exploitation front in O/ZG Rudna.

Significant differences in the mechanical modeling of confined growth predicted by the Lagrangian and Eulerian formulations

This paper presents an Eulerian formulation of growth for general elastic anisotropic response. The constitutive equations model homeostasis, which is the inelastic process causing the elastic deformation measures to tend towards their homeostatic values. The numerical implementation into ABAQUS using robust, strongly objective integration algorithms for the evolution equations is discussed. Differences between the Eulerian and the Lagrangian multiplicative formulations of growth are examined using examples modeling partially unconfined and confined growth.

Quantitative stress measurement of elastic deformation using mechanoluminescent sensor: An intensity ratio model.

The mechanoluminescent (ML) sensor is a newly developed non-invasive technique for stress/strain measurement. However, its application has been mostly restricted to qualitative measurement due to the lack of a well-defined relationship between ML intensity and stress. To achieve accurate stress measurement, an intensity ratio model was proposed in this study to establish a quantitative relationship between the stress condition and its ML intensity in elastic deformation. To verify the proposed model, experiments were carried out on a ML measurement system using resin samples mixed with the sensor material SrAl2O4:Eu2+, Dy3+. The ML intensity ratio was found to be dependent on the applied stress and strain rate, and the relationship acquired from the experimental results agreed well with the proposed model. The current study provided a physical explanation for the relationship between ML intensity and its stress condition. The proposed model was applicable in various SrAl2O4:Eu2+, Dy3+-based ML measurement in elastic deformation, and could provide a useful reference for quantitative stress measurement using the ML sensor in general.

A new approach to modeling early cardiac morphogenesis during c-looping

The objective of this paper is to formulate a theoretical structure for modeling early cardiac morphogenesis based on a recently developed Eulerian formulation of growth of soft tissues which is insensitive to unphysical arbitrary specifications of total deformation, growth deformation, a reference configuration and an intermediate stress-free configuration. In this theory, Eulerian evolution equations are proposed for an elastic dilatation Je and a second order elastic distortional deformation tensor Be′. These evolution equations depend on the velocity gradient and they include homeostasis, which is the inelastic rate process that causes a tendency for Je and Be′ to approach their homeostatic values. Specific new expressions are proposed for scalar measures of elastic strains of material line elements, the elastic shear strain between a pair of material fibers and an elastic measure of area strain, which model different stages of c-looping associated with a simplified heart tube model of cardiac morphogenesis. The strain energy function and stress depend on these elastic deformation measures. Also, robust strongly objective numerical algorithms are developed for integrating the evolution equations. Future work is planned to implement the model into a finite element code for calculations of more realistic heart geometry and for study of constitutive models of homeostasis and the homeostatic state.

Geomechanical analysis of location and conditions for mining-induced tremors in LGOM copper mines

Abstract This paper presents the results of the statistical analyses of rock mass seismicity associated with O/ZG Rudna exploitation and geomechanical analyses concerning the location and conditions of tremor occurrences in LGOM conditions, illustrated by the example of O/ZG Rudna. As part of the statistical analyses, the assessment of rock mass seismicity formation in O/ZG Rudna throughout the whole mine area in the years 2006–2015 is presented, the results of which were the basis for subsequent geo-mechanical analyses. Within the parameters of seismic activity, the analysis covered the number of recorded events, the total value of energy emission and the index of individual energy expenditure. The presented analyses also refer to the locations of tremor source epicentres in relation to the exploitation front, distinguished into low energy and high energy tremors located ahead of the exploitation front, in the area of opening-up works and gobs. These recent results were the starting point for research and calculations on geo-mechanical analyses. These numerical calculations using the finite element method (FEM) carried out the energy density distribution of elastic deformation in the vicinity of the exploitation front. FEM calculations were designed to establish the factors and conditions that determine the location of tremor sources and the mechanism of rock destruction. Both of these factors are directly related to the magnitude of the energy emitted during the tremor. Appropriate energy measurements of elastic deformation have been adopted to determine rock mass areas which are potentially threatened by tremor occurrences of varying energy. Measures of the energy density of shear and volumetric strain enable the determination of the nature of rock mass destruction in the vicinity of mine workings, which in turn gives the basis for linking these measurements with tremor energy and location relative to the exploitation front. The results of numerical computations were compared with the results of statistical analyses on the locations of tremor sources with different energies in relation to the exploitation front in O/ZG Rudna.

Computer Aided Measurement of Elastic Deformations of a Work Piece in the Turning Process

In the turning processes, one of the causes which generate processing errors is represented by the elastic deformation of the work piece. This leads to modifications along the entire length of the considered work piece.In this study, the authors have searched for possibilities to analyze and establish values of elastic deformations corresponding to the machine parts obtained in the turning process. This involves the measurement and interpretation of the signal which describes how far or how close the measuring device is from the work piece. This action was performed with an optical transducer.In this way, we have measured the elastic deformation by exploring the work piece length with an optical sensor; also, we have developed a processing method of a signal generated by the optical sensor which was tested, both experimentally and in real work conditions and it lead to a validated procedure for measuring-processing data.The result of this study creates the prospects to analyze step by step the relation between the cutting force and the elastic deformation of the processed work piece. As a solution for solving the problem we have to mention the creation of a device which can make corrections by means of trough transversal displacement of the cutting tool.

On finite strain micromorphic elastoplasticity

In the micromorphic continuum theory of Eringen, it was proposed that microstructure of materials could be represented in a continuum framework using a micro-deformation tensor governing micro-element deformation, in addition to the deformation gradient governing macro-element deformation. The paper formulates finite strain micromorphic elastoplasticity based on micromorphic continuum mechanics in the sense of Eringen. Multiplicative decomposition into elastic and plastic parts of the deformation gradient and micro-deformation are assumed, and the Clausius–Duhem inequality is formulated in the intermediate configuration B ¯ to analyze what stresses, elastic deformation measures, and plastic deformation rates are used/defined in the constitutive equations. The resulting forms of plastic and internal state variable evolution equations can be viewed as phenomenological at their various scales (i.e., micro-continuum and macro-continuum). The phenomenology of inelastic mechanical material response at the various scales can be different, but for demonstration purposes, J 2 flow plasticity is assumed for each of three levels of plastic evolution equations identified, with different stress, internal state variables, and material parameters. All evolution equations and a semi-implicit time integration scheme are formulated in the intermediate configuration for future coupled Lagrangian finite element implementation. A simpler two-dimensional model for anti-plane shear kinematics is formulated to demonstrate more clearly how such model equations simplify for future finite element implementation.

In-Process Measurement of Elastic Deformation of a Large Deep-Drawing-Die with Fusion of Experiment and Numerical Analysis

We measured elastic deformation of a large deep drawing die in-process and visualized it with a fusion technique of numerical analysis and experiments with multipoint die support. We found that displacement by elastically deforming a press machine bolster is up to 0.15 mm when measured directly by displacement sensors. Lower die profile displacement for a half size fender is estimated at 0.25 mm. We numerically analyzed elastic die deformation using multipoint die support to measure and visualize deformation indirectly. We calculated reactive force distribution on the cavity surface and to know it differs with according to distribution pattern of support points, and visualized elastic deformation die patterns.

Stress relaxation in CdHgTe/CdTe heterostructures

Based on our analysis of the results of measurements of elastic deformation in CdxHg1−xTe/CdTe heterostructures it is shown that the degree of relaxation of the crystal lattice for Cd0.2Hg0.8Te films 1 µm thick with a working temperature of 273 K is 0.8766, which supports the idea of almost full relaxation of the mismatch stress for such thicknesses of A2B6 films.

Mechanical Behavior of Coke as a Material with Randomly Distributed Pores

A miniature bending test method was developed for measuring mechanical properties of coke with better accuracy. Mechanical properties of formed and conventional cokes at room temperature were measured by this method and the effects of pore on them were investigated, taking statistics into consideration. Deformation of a porous body was analyzed by the finite element method combined with Monte Carlo method and an attempt was made to develop a method to estimate Young's modulus of coke matrix.The results are as follows.(1) Linear correlation was found between Young's moduli of cokes and maximum bending stress, and a possibility of estimating the strength from the measurements of elastic deformation was shown.(2) Young's modulus of coke decreased with increasing porosity. The decreasing rate of formed coke was different from that of conventional cokes.(3) Young's modulus of coke matrix was estimated by the method presented here from apparent Young's moduli including the effects of pores.(4) From a new viewpoint a comparison was made between the mechanical properties of formed coke and that of conventional one, using the Young's moduli of coke matrix obtained as above.

Measurement of elastic deformation of rotating objects by using holographic interferometry

Double-exposure holographic interferometry is applied to measure the elastic deformation of rotating objects. The first exposure is made in the rotating state and the second in the static state. The precise positioning of the object between the two exposures is obtained by using holographically produced Haidinger's fringes.