Papers by Keyword: Strain Analysis

Abstract: Previous studies have demonstrated that crack geometry influences strain generation in cracked shafts under excitation loading. The behavior of strain generation varies notably under transverse loading suggesting that the crack orientation could have a significant effect on strain behavior under excitation. This computational study aims to investigate the influence of different crack orientations on strain behavior. The analysis examines the strain at crack tips and the effects of loading on crack alignment under transverse excitation. Crack-controlled parameters, such as shape factor, characteristic length, and orientation parameter, are found to be significant factors governing strain behavior. Specifically, cracks with greater circularity and larger characteristic lengths exhibit higher strain levels under excitation. Crack orientation becomes particularly significant in conveying the strain from the affected area of excitation loading through the crack front, especially in the case of a straight crack, resulting in high strain levels at both tips and distinct strain generation behavior. The findings highlight the significant impact of excitation-affected areas near the excitation location on strain generation over crack geometry. This underscores the potential risk of existing cracks in the shaft and the importance of these factors on strain generation behavior. This study enhances understanding of how crack orientation impacts strain behavior, offering valuable insights for structural integrity assessment and design optimization in engineering applications.

Abstract: The main objects of this paper are to deal with the new technology of metal sheet forming using the incremental single-point tool to form the sheet metal. However, due to the needed long time to form the metal in incremental so that we used punching and then incremental forming to geometry the final shape of the product. By measuring the thickness and longitudinal strain and evaluating the hoop strain, it was noticed that the less depth in punching with less step size in incremental forming have a better strain effect in metal sheet forming. Keywords: Single point, incremental forming, Strain analysis, step size.

Abstract: A strain-based elastic constant identification method is proposed to determine the elastic constants of fiber-reinforced composite rectangular laminates using three measured strains of the plates subjected to uniaxial load testing. In the proposed method, the measured normal strains in 0°, and 45°, and 90° directions, respectively, of the plate made of one composite material subjected to uniaxial tensile testing are used to identify four elastic constants of the constituent composite material via a two-level optimization approach. The objective function used for constructing the two-level optimization problem consists of the sum of the differences between the experimental and theoretical predictions of the three strain components and a strain restraining function, which is used to help even up the effects of the measured strains on the identified elastic constants. The accuracy of the proposed method has been verified via an experimental approach.

Abstract: Evaluation of surface damage layers formed by mechanical grinding processes is indispensable in epi-ready SiC wafer preparation. As well as microstructure, the analysis of local strain distribution in the damage layers gives a clue on control of the wafer quality. Advanced electron backscatter diffraction (EBSD) technique is applied to evaluate the strain distribution of the damage layers. It is revealed that the elastic strain distribution can be classified into a hierarchy of three regions with respect to depth from the surface. Combining EBSD analysis with TEM observation, large compressive elastic strain and misorientation are introduced in the highly-defective region underneath the ground wafer surface. In addition, the gradient distribution of the strain is observed clearly below the highly-defective region. The knowledge of correlating between strain distribution and microstructure is promising to control the damage layer for the wafer preparation.

Abstract: The paper presents the results of mechanical properties testing of thin sheet metal of INCONEL 625 and 718 alloys. These studies are a continuation of experience in the preparation of the technological characteristics of metal strips plasticity necessary for carrying out numerical simulations [1]. In order to process sheets now become necessary to design the process using software such as thermo-mechanical simulation e.g. Eta/DYNAFORM. On the road of numerical simulation are sought optimal conditions for processing sheets. It brings reducing the cost of industrial tests. However, becomes strictly necessary characteristics of mechanical and technological properties describing the characteristics of the charges for forming. Here the problem is solved if we forming limit curves (FLCs) designated and technological tests conducted. Using the FLCs is comprehensively defined stamping sheet metal press formability and technological tests allow the mapping of the actual operating conditions selected stamping operations. In the presented study used modern digital analyzer AutoGrid of local deformations and the method of image analysis of deformed mesh subdivision. The use of mesh analyzer and vision systems method significantly speeds up the possibility of producing FLCs. Also measurement accuracy is very high. Selected Inconel alloys are evaluated quantitatively and qualitatively by preparing their properties characterization. The acquired data entered into the database material properties of sheet metal and used in the numerical simulation of stamping process of Inconel 625 cone drawpiece. The legitimacy of the use of modern strain analyzer AutoGrid has been confirmed.

Abstract: The work presents the aproach of the finite element investigation of the cardan transmission joint. We treat the problem of structural behaviour, such as analyses that target the strength-related behaviour. It is thus sought to determine certain parameters (nodal displacements, stresses, strains) in the conditions of applying various types of loads - forces, pressures or moments. For this, we used a software for finite element analysis – Cosmos - a product integrated in the Solidworks package. We insisted on calculation of the cardan transmission for Dacia 1307 but they can be easily transposed also to other typodimensions of cars, machines or medical devices from the same category.

Abstract: An experimental study is conducted to explore a new method to calculate the strain in axisymmetric workpiece forming. When designing deep drawing die for an axisymmetric workpiece, the principal strain during the forming is needed to estimate formability and to decide whether the forming is finished in one pass. Strain calculation is a difficult task, so an ideal same area method used to calculate the strain for an axisymmetric workpiece along with a correction same area method considered thickness reduction rate is proposed here. The deep drawing test for an axisymmetric workpiece is used to obtain the strain along circumference and generatrix direction. The strain along the two directions calculated by the ideal same area method and correction same area method is compared with experimental results. The results show that ideal same area method can be used to calculate the strain during the forming process for an axisymmetric workpiece and the result from correction same area method is close to the experiment.

Abstract: The Chengzigou hydropower station of composite geomembrane rockfill dam as an example of the dam body and the composite geotechnical membrane stress and deformation characteristics are used nonlinear elastic model - Duncan EB model establish three-dimensional finite element model of rockfill,by using the large finite element softwareFLAC^3D,whice provided geogrid element to simulate lexible geomembrane shear interaction with soil.The stress and deformation of the dam and the composite geomembrane is calculated under two conditionscompletion period and impoundment period.And analyze the change of the stress and strain distribution rule,whice will provide the basis for the design of the geomembrane.

Abstract: The length of crack extension under stable crack extension is measured by digital image correlation technology and based on mixed-mode I/II fracture test. Quantitative analyses of the fracture properties are provided for thin sheet metals at stable crack extension under mode I, mode II and mixed-mode I/II loading conditions. The strain field of the crack tip at crack initiation is calculated by VIC-2D. It is suggested that the location of crack initiation is not at the crack tip. The fracture of recycled thin sheet metals is tough due to the large plastic deformation; mode I crack is the most difficult to extend; the load-carrying capacity is the minimum in 45° loading.

Abstract: Through the comparative analysis of theoretical and experiment results, this paper proved that the formulas for solving the strain of composite beams are correct, and the strain is consistent with the plane cross-section assumption. In order to reduce the influence of friction, resin membranes were placed in steel-steel composite beams and aluminum-steel composite beams. The strain measurements were performed on composite beams with and without adding resin, the influence of friction between the composite beams is analyzed by the comparison of strain data,.