scholarly journals MATERIAL PROPERTIES AND RESIDUAL STRESSES OF ROLLED THICK PLATES AND THEIR EFFECTS ON STATIC STRENGTH

2010 ◽  
Vol 66 (2) ◽  
pp. 253-263 ◽  
Author(s):  
Katashi FUJII ◽  
Shinsuke ISHIKAWA ◽  
Yasunori NAKAMO ◽  
Masato TANAKA
Keyword(s):  
Residual Stresses ◽  
Material Properties ◽  
Static Strength ◽  
Thick Plates

PREDICTION OF PEEK RESIN PROPERTIES FOR PROCESSING MODELING USING MOLECULAR DYNAMICS

2021 ◽  
Author(s):  
KHATEREH KASHMARI ◽  
PRATHAMESH DESHPANDE ◽  
SAGAR PATIL ◽  
SAGAR SHAH ◽  
MARIANNA MAIARU ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Residual Stresses ◽  
Crystallization Kinetics ◽  
Material Properties ◽  
Elevated Temperatures ◽  
Processing Parameters ◽  
Thermomechanical Properties ◽  
Volumetric Shrinkage ◽  
Processing Temperature ◽  
Wide Range

Polymer Matrix Composites (PMCs) have been the subject of many recent studies due to their outstanding characteristics. For the processing of PMCs, a wide range of elevated temperatures is typically applied to the material, leading to the development of internal residual stresses during the final cool-down step. These residual stresses may lead to net shape deformations or internal damage. Also, volumetric shrinkage, and thus additional residual stresses, could be created during crystallization of the semi-crystalline thermoplastic matrix. Furthermore, the thermomechanical properties of semi-crystalline polymers are susceptible to the crystallinity content, which is tightly controlled by the processing parameters (processing temperature, temperature holding time) and material properties (melting and crystallization temperatures). Hence, it is vital to have a precise understanding of crystallization kinetics and its impact on the final component's performance to accurately predict induced residual stresses during the processing of these materials. To enable multi-scale process modeling of thermoplastic composites, molecular-level material properties must be determined for a wide range of crystallinity levels. In this study, the thermomechanical properties and volumetric shrinkage of the thermoplastic Poly Ether Ether Ketone (PEEK) resin are predicted as a function of crystallinity content and temperature using molecular dynamics (MD) modeling. Using crystallization-kinetics models, the thermo-mechanical properties are directly related to processing time and temperature. This research can ultimately predict the residual stress evolution in PEEK composites as a function of processing parameters.

scholarly journals Longitudinal Residual Stress Analysis in AA2024-T3 Friction Stir Welding

2013 ◽  
Vol 7 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Pierpaolo Carlone ◽  
Gaetano S. Palazzo
Keyword(s):  
Friction Stir Welding ◽  
Residual Stresses ◽  
Process Parameters ◽  
Material Properties ◽  
Stress Measurement ◽  
Dynamic Performance ◽  
Contour Method ◽  
Influence Of Process Parameters ◽  
Friction Stir ◽  
Longitudinal Residual Stress

Friction Stir Welding (FSW) is an innovative solid-state joining process, which is gaining a great deal of attention in several applicative sectors. The opportune definition of process parameters, i.e. minimizing residual stresses, is crucial to improve joint reliability in terms of static and dynamic performance. Longitudinal residual stresses, induced by FSW in AA2024-T3 butt joints, have been inferred by means of a recently developed technique, namely the contour method. Two approaches to stress measurement have been adopted; the former is based on the assumption of uniform material properties, the latter takes into account microstructural effects and material properties variations in the welding zones. The influence of process parameters, namely rotating and welding speeds, on stress distribution is also discussed.

Influence of Forming Residual Stresses on the Welding Distortions of Two Thick Plates

2009 ◽  
Vol 83-86 ◽  
pp. 125-132 ◽  
Author(s):  
Sebastien Gallée ◽  
Antoine Martin ◽  
Vincent Robin ◽  
Daniel Nelias
Keyword(s):  
Numerical Simulation ◽  
Electron Beam ◽  
Heat Source ◽  
Residual Stresses ◽  
Electron Beam Welding ◽  
Initial Conditions ◽  
Rolling Process ◽  
Vacuum Vessel ◽  
Thick Plates ◽  
Simulation Results

The manufacturing of the ITER (International Thermonuclear Experimental Reactor) vacuum vessel involves the welding of thick deformed plates. The aim of this study is to investigate the influence of forming residual stresses on the welding distortions of two thick plates. The plates are deformed using a three point rolling process. A first numerical simulation is performed to investigate the residual stresses induced by this process. The forming residual stresses are taken into account as initial conditions to perform the electron beam welding simulation of a deformed plate. This simulation first requires calibrating the heat source. Two welding simulations are then performed: the first one with residual stresses and the second one without. The comparison of the simulation results points out a low effect of the residual stresses on the electron beam welding distortions. As a result, in the next electron beam welding simulations of the vacuum vessel, no forming residual stresses will be taken into account.

Analysis and Prediction of Surface Integrity in Machining: A Review

2014 ◽  
Vol 610 ◽  
pp. 1002-1020 ◽  
Author(s):  
Yuan Gao ◽  
Xin Huang ◽  
Ming Jie Lin ◽  
Zheng Guo Wang ◽  
Rong Lei Sun
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Material Properties ◽  
Cutting Parameters ◽  
Mechanical Parameters ◽  
Factors Affecting ◽  
Grain Size And Shape

Surface integrity is widely used for evaluating the quality of machined components. It has a set of various parameters which can be grouped as: (a) topography parameters such as surface roughness, textures and waviness (b) mechanical parameters such as residual stresses and hardness, and (c) metallurgical state such as microstructure, phase transformation, grain size and shape, inclusions etc. Surface roughness and residual stresses are among the most significant parameters of surface integrity, so that it is worth investigating them particularly. Many factors affect the surface integrity of machined components, including cutting parameters, tool parameters, material properties and vibrations. We can make prediction and optimization for surface integrity by taking advantage of these factors. This paper reviews previous studies and gives a comprehensive summary of surface integrity in the following order: introduction of surface integrity, main parameters of surface integrity, factors affecting surface integrity, prediction and optimization for surface integrity.

Prediction of Residual Stresses in Welded T- and I-Joints Using Inherent Strains

1996 ◽  
Vol 118 (2) ◽  
pp. 229-234 ◽  
Author(s):  
M. G. Yuan ◽  
Y. Ueda
Keyword(s):  
Residual Stresses ◽  
Material Properties ◽  
Strain Distribution ◽  
Elastic Analysis ◽  
Fillet Weld ◽  
Average Temperature ◽  
Input Material ◽  
Geometric Ratio ◽  
Inherent Strain ◽  
Good Agreement

In order to develop a predicting method of residual stresses in fillet welded T- and I-joints, a concept of inherent strain, being regarded as a source of the residual stresses, was introduced. With the proposed method, the residual stress of an interested weldment may be predicted by performing an elastic analysis, in which the inherent strain is replaced to equivalent distributed loads. The inherent strain distributions in various welded T- and I-joints were investigated by numerical simulations. The results showed that the inherent strains distributing in flange side and in web side of the several joints are almost the same. The inherent strains vary not only with the average temperature rise due to welding, but with the geometric ratio of the joints. Being simplified by a trapezoid curve, the inherent strain distribution in a fillet weld was expressed by formulas, in which heat input, material properties, and geometric dimensions were taken into account. Welding residual stresses in T- and I-joints, predicted by the proposed method employing the derived formulas, were compared with those obtained by thermal elasto-plastic analysis, and good agreement was recognized. The validity of the proposed method was also confirmed by experiments.

Fundamentals of Residual Stresses in Joints Between Dissimilar Materials

MRS Bulletin ◽  
1995 ◽  
Vol 20 (1) ◽  
pp. 37-39 ◽  
Author(s):  
B.H. Rabin ◽  
R.L. Williamson ◽  
S. Suresh
Keyword(s):  
Residual Stresses ◽  
Material Properties ◽  
Critical Stress ◽  
Failure Mechanisms ◽  
Dissimilar Materials ◽  
Free Edge ◽  
Structural Components ◽  
Failure Characteristics ◽  
Stress Components ◽  
Metal Joint

When a discontinuity in material properties exists across a bonded interface, stresses are generated as a result of any thermal or mechanical loading. These stresses significantly affect strength and failure characteristics and may be large enough to prevent successful fabrication of a reliable joint. The use of an interlayer material to successfully reduce mismatch stresses, thereby preventing joint failure or improving joint strength and reliability, requires knowledge of failure mechanisms and of the effects of interlayer properties on the critical stress components.The origin of residual stresses developed during cooling of a ceramic-metal joint from an elevated fabrication temperature is illustrated qualitatively in Figure 1. Away from edges, the in-plane (parallel to interface) stresses are typically compressive in the ceramic and tensile in the metal. These stresses can cause cracking perpendicular to the interface, leading to spalling or delamination failures. Such failures are frequently observed in thin-film and coating geometries. Where the interface intersects a free edge, large shear and axial (perpendicular to the interface) stresses are generated. The edge stresses are typically tensile within the ceramic and tend to promote crack propagation within the ceramic parallel and adjacent to the interface. This is the most commonly observed failure mode in bonded structural components.

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