Equivalent Elastic Strain Research Articles

Research on High Temperature Low Cycle Fatigue Crack Propagation of 2.25Cr-lMo Steel under Complex Stress State

The crack propagation law of 2.25Cr-1Mo steel with notched cylinder was researched under high temperature low cycle fatigue. The crack propagation life was viewed by fatigue experiment and the equivalent stress-strain on the crack tip was calculated by the ANSYS. The equivalent J-integral range which was computed by equivalent elastic and plastic strain ranges were employed to denote the fatigue crack propagation rate. The results showed that crack propagation law of this material under complex stress state can be characterized by equivalent J-integral ranges and the relation between da/dN and ΔJf is not influenced by the type of notch and the load strain range.

Stress and Strain Analysis of First Stage Rotating Blades of Flue Gas Turbine Blades

Flue gas turbine is the key equipment of the refinery catalytic cracking unit and blades are important component parts. However, blades faults are accounted for a large proportion of various failures in the flue gas turbine. According to it, ANSYS finite element software is applied to analysis Level 1 dynamic blade stress and strain and obtained the stress and strain distribution of the gas turbine, the greatest stress is at the root of the blade suction side and pressure on both sides of the Ministry basin, the maximum stress intensity value is 169.698MPa and the maximum equivalent elastic strain is 0.194×10-3.Then at the basic of the stress analysis to strength check of blade’s body and at last proved that it meet the design stress intensity. Through theoretic analysis and the result of stress and strain analysis is proved that ANSYS software is acceptable and efficient. At the same time it provides a theoretical basis for engineering.

Prediction of long-term settlement on soft clay using shear wave velocity and damping characteristics

This paper presents a method of calculating long-term settlement of a loaded pad on soft clay at Klang, Selangor, Malaysia where the soil model is treated as an anelastic material of viscoelastic property. Initially, an elastic shear modulus ( G) value from shear wave velocity profiles of the seismic tests from spectral analysis of surface wave (SASW) and continuous surface wave (CSW) tests was obtained. A value of damping ( D) at an equivalent elastic strain is then calculated from the hysteresis of the plate load tests corrected to equivalent strain using the Damping–Strain formula. The calculated elastic settlement and its equivalent damping are then used to calculate the long-term settlement by applying the generalised viscoelastic formula. Comparisons to traditional methods of settlement predictions were made and the viscoelastic formula has shown better agreement to the observed settlement. Further modification of the settlement formula is introduced to improve the settlement accuracy to 10%.

The Lightweight Design and Improvement of Aluminum Alloy Automobile Wheel

This paper models the auto wheel by UG, and made analysis through ANSYS Workbench software. The result of finite element analysis shows that the maximum stress is much less than the allowable stress of aluminum alloy wheels. So auto wheels can be optimized further. Then structural optimization is made to minimize the weight of the wheel. The static analysis and fatigue analysis to the optimized wheel is made then. The results of equivalent stress, equivalent elastic strain and total deformation are similar with the results that before optimize, but its weight is decreased. It gains the goal of lighting weight, decreasing fuel consumption and reducing pollution.

Finite element modeling of high-pressure deformation and phase transformation of silicon beneath a sharp indenter

Modeling of the mechanical response of single crystalline silicon to a sharp indenter is an essential step for the optimization of wafer manufacturing processes. In this paper, deformation of silicon during indenter loading and unloading was analyzed by the finite element method, and the changes of stress field and high-pressure phase distribution were dynamically simulated. We found that the deformation of silicon in nanoindentation can be simply characterized by two factors: one is the elastic strain of each high-pressure phase and the other is the equivalent elastic strain of each phase transformation. In loading, indentation energy is absorbed mostly by phase transformation, and accumulated as the elastic strain of the high-pressure phases. The distribution pattern of the high-pressure phases beneath the indenter is independent of the indentation load, and the depth of the phase-transformed region is approximately twice the indentation depth. In unloading, high-pressure phases except the β-Sn phase undergo reverse phase transformations. The β-Sn phase does not transform back to the diamond phase but changes to other non-equilibrium phases, which becomes the dominant reason for residual strain. During unloading, the non-equilibrium phase expands from the diamond phase region toward the indenter tip, while the boundary between the non-equilibrium phase and the diamond phase remains unchanged. The unloading mechanism is independent of the change in the maximum indentation load and the presence/absence of pop-out events.

A Study of Residual Elastic Strain Distribution in an AZ91 Mg Alloy Bar Loaded in Four Point Bending

This paper presents a study of the residual strain field within a high pressure die cast (HPDC) AZ91 Mg alloy bar subjected to four point bending. The technique employed for this purpose is high energy synchrotron X-ray diffraction. Strain scanning using polychromatic X-ray beam allows the collection of multiple peak diffraction patterns and monitoring of small peak shifts as a function of beam position. These shifts allow collective interpretation in terms of the equivalent macroscopic residual elastic strain. Residual elastic strain distributions were studied in the sections subjected to pure bending and also in sections of contact between the sample and the rollers. These experimental results are compared with the predictions from a finite element analysis of contact and deformation. Good agreement is found between the modelled and measured results. It is hoped that these results help improved understanding of complex deformation behaviour of thin-walled HPDC AZ91 components and provide useful background information for lifing assessment of such structures.

デンタルインプラントと下顎骨の力学的相互作用に及ぼす固定式補綴装置の材質の影響

The purpose of this study is to develop a detailed 3-Dimension mandibular model with dental implants on the basis of CT data and to conduct stress analysis to characterize the effects of the material type of prosthesis on stress/strain distribution in the mandibular bone. Three types of materials, a polymer and two metals, with different elastic properties were chosen as the prosthesis materials. The analytical results showed that the Mises equivalent stress and equivalent elastic strain along the circumference of the implant at distal side were much higher than in the anterior region. It was also shown that the stress/strain concentration at the bone increased with decreasing the prosthesis stiffness. The stress/strain concentration observed in the circumference of the implants could be the driving force for loosening and fracture of the implants.

The determination of a continuum mechanics equivalent elastic strain from the analysis of multiple diffraction peaks

Stress measurement by neutron or synchrotron x-ray diffraction is a nondestructive technique that provides insights into strain and/or stress fields deep within engineering components and structures. The technique is seeing increased use for the validation of finite element process models, however, present FE models predict a continuum elastic strain rather than diffraction strains. An expression is therefore derived for a physically realistic weighting of strains obtained from multiple single peak diffraction measurements of internal elastic strain in order to determine a macroscopic equivalent elastic strain, and hence stress. A practical approach to the use of the expression is suggested. A similar expression is derived for the equivalent weighting used in Rietveld refinements, for both polychromatic and monochromatic sources, which is applicable to both neutron and x-ray diffraction. The use of these expressions is illustrated for both textured and untextured, cubic (steel) and hexagonal (titanium) symmetry polycrystals. The physically realistic weighting is different from that used in the Rietveld refinement however both provide good estimates of the macroscopic equivalent elastic strain.

Design Improvement of the Jellyfish Valve for Long-term Use in Artificial Hearts

In a previous communication, we reported a leaflet fracture in a Jellyfish valve that was incorporated into a blood pump, after a 312-day animal implant duration. Subsequent finite element analysis revealed that the fracture location was consistent with an area of maximum strain concentration. Therefore, the aim of this study was to improve the durability in the light of these findings. Based on the engineering analysis results, a new valve seat having a concentric ring of 0.5-mm width, located at a radius of 7.0 mm, was designed and fabricated. Accelerated fatigue tests, conducted under the conditions recommended by ISO 5840, demonstrated that the durability of this new prototype was extended by a factor of 10, as compared to the original valve. Moreover, further finite element analysis indicated that the maximum equivalent elastic strain of the proposed new valve was reduced by 52.3% as compared to the original valve. Accordingly, it has been confirmed that the modified Jellyfish valve is suitable for use in long-term artificial hearts.

710 強靭化DP鋼板の形状凍結性に及ぼす複合組織の影響(オーガナイズドセッション : 超成形・超塑性と材料)

This study was carried out for the purpose of evaluating product reliability (the shape freezing property ) in plastic working of high-tensile DP steel plate, from both viewpoints of analytical and experimental procedure. As a result of the simple V-bending test, DP steel had excellent shape freezing property further than high-tensile steel having single phase microstructure and same tensile strength as DP steel. The basic V-bending test in this study gives us accurate evaluation of shape freezing property in various kinds of commercial steel. The total of the equivalent elastic strain energy is effective parameter for unified evaluation guideline of the shape freezing property of steel after plastic working. It is possible that the shape freezing property (springback) in plastic working (bending) of DP steel is predicted by considering the microstructure and macrostructure.

Second-order continuity tensor and stiffness degradation of aluminum alloy 2024T3 under large strain at room temperature

A symmetric second-order continuity tensor is proposed to characterize anisotropic damage of anisotropic materials based on the hypothesis of equivalent elastic strain energy. On the basis of the equivalent elastic strain energy hypothesis, the relation between the effective elastic properties and the continuity tensor has been formulated. The current formulation does not require the assumption that the principal coordinate system of damage must coincide with that of the material. In a two-dimensional damage analysis, the state of damage can be represented by a Mohr’s circle of continuity. The proposed damage characterization technique has been successfully applied to an example case, where aluminum alloy 2024T3 specimens were strain-damaged by uni-axial tension. The experimental results show that the effects of strain damage can cause degradation of the material stiffness. On the other hand, the overall elastic orthotropy of the material does not increase with the degree of damage. The proposed continuity tensor has been found to be capable of describing this phenomenon. The principal values and the principal directions of the continuity tensor have been determined. The mean value of the principal values can represent the magnitude of the damage, while the principal direction of the continuity tensor may provide information about the damage mechanism.

A squeeze film flow processibility tester

AbstractThe applicability of the squeeze film flow geometry in a processibility tester is investigated in this study. A prototype processibility tester has been built by retrofitting it to a servohydraulic load frame. Several processibility parameters such as viscosity and the elastic component in the melt have been investigated. With the concept of equivalent elastic strain, the extrudate swell can be semi‐quantitatively predicted from the squeeze film flow experiment. © 1994 John Wiley & Sons, Inc.

On the Transmission of Plane Waves through Layered Linear Viscoelastic Media

The propagation of two-dimensional time harmonic waves through a plane layered viscoelastic medium is considered in terms of the equivalent elastic plane strain problem with modified Lamé constants that are complex and frequency dependent. The problem is formulated directly in terms of stresses and displacements rather than potentials and is solved by matrix methods. If the incident wave is not attenuated in the direction parallel to the layering, as would occur if the incident wave were to travel through a semi-infinite elastic half-space before striking the viscoelastic layers, interface waves could be generated only if one of the layers is “pseudoelastic,” i.e., has at least one real wave speed. In this case, interface waves may be generated in the same manner as in the purely elastic case. If the incident wave is attenuated in this direction, however, interface waves could be generated for specific angles of incidence and material properties.