Effect of process parameters on stress and strain of hybrid deposition and micro-rolling

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xushan Zhao ◽  
Yuanxun Wang ◽  
Guilan Wang ◽  
Runsheng Li ◽  
Haiou Zhang
Keyword(s):  
Residual Stress ◽  
Plastic Strain ◽  
Three Dimensional ◽  
Substantial Effect ◽  
Weld Bead ◽  
Stress And Strain ◽  
Residual Tensile Stress ◽  
Content Type ◽  
Orthogonal Optimization ◽  
Selection Of

Purpose This paper aims to summarize the influence law of hybrid deposited and micro-rolling (HDMR) technology on the shaping strain and residual stress. And the rolling parameters combination was further optimized to guide the actual production. Design/methodology/approach This paper proposed a three-dimensional coupled thermo-mechanical model of the HDMR process. The validated model is used to investigate the influences of rolling parameters on stress and plastic strain (the distance between the energy source and roller [De–r], the rolling compression [cr] and the friction coefficient [fr]). The orthogonal optimization of three factors and three levels was carried out. The influence of rolling parameters on the plastic strain and residual stress is analyzed. Findings The simulation results show that HDMR technology can effectively increase the shaping strain of the weld bead and reduce the residual tensile stress on the weld bead surface. Furthermore, the influence of rolling parameters on stress and strain is obtained by orthogonal analysis, and the corresponding optimal combination is proposed. Also, the rolling temperature significantly affects the residual stress, and the rolling reduction has a substantial effect on the plastic deformation. Research limitations/implications Owing to the choice of research methods, this paper failed to study microstructure evolution. Originality/value This paper provides a reference principle for the optimal selection of rolling parameters in HDMR.

scholarly journals Elasto-plastic analysis of the contact region between a rigid ellipsoid and a semi-flat surface

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879739 ◽  
Author(s):  
Pengyang Li ◽  
Lingxia Zhou ◽  
Fangyuan Cui ◽  
Quandai Wang ◽  
Meiling Guo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Plastic Strain ◽  
Contact Pressure ◽  
Contact Region ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Effective Plastic Strain ◽  
Normal Forces ◽  
Von Mises

When the load acting on a mechanical structure is greater than the yield strength of the material, the contact surface will undergo plastic deformation. Cumulative plastic deformation has an important influence on the lifespan of mechanical parts. This article presents a three-dimensional semi-analytical model based on the conjugate gradient method and fast Fourier transform algorithm, with the aim of studying the characteristic parameters of the contact region between a rigid ellipsoid and elasto-plastic half-space. Moreover, normal forces and tangential traction were considered, as well as the contact pressure resulting from various sliding speeds and friction coefficients. The contact pressure, effective plastic strain, von Mises stress, and residual stress were measured and shown to increase with increasing sliding velocity. Finally, when the friction coefficient, contact pressure, and effective plastic strain are increased, the von Mises stress is also shown to increase, whereas the residual stress decreases.

Residual Stress Measurements Revealing Weld Bead Start and Stop Effects in Single and Multi-Pass Weld-Runs

2005 ◽  
Author(s):  
Peter J. Bouchard ◽  
Javier R. Santisteban ◽  
Lyndon Edwards ◽  
Mark Turski ◽  
Jon James ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Weld Bead ◽  
Contour Method ◽  
Stress And Strain ◽  
Outer Diameter ◽  
End Effects ◽  
Stress Measurements ◽  
Stress Variations ◽  
Welding Direction

This paper describes transverse residual stress and strain measurements aimed at quantifying end effects in single and multi-pass weld-runs. Two test specimens are examined: a 60 mm long weld bead deposited on the surface of a 180 mm × 120 mm × 17 mm thick stainless steel plate, and a 62° arc-length multi-pass repair weld in a 432 mm outer diameter, 19.6 mm thick stainless steel pipe girth weld. The residual stress measurements were made by employing the relatively new Contour method and by neutron diffraction using ENGIN-X, the engineering spectrometer at the ISIS facility of the Rutherford Appleton Laboratory (UK). The measured underlying transverse residual stress levels are observed to be essentially uniform directly beneath the weld bead in the plate specimen and in the heat affected zone beneath the capping passes moving from mid-length towards the stop-end of the pipe repair. However, results from both test components demonstrate the existence of short-range concentrations of transverse residual stress along the welding direction owing to individual weld capping bead start and stop effects. Such short length-scale stress variations must be allowed for when interpreting residual stress measurements from line-scans. The experimental work also demonstrates the importance of knowing the expected stress or strain distribution prior to choosing measurement lines for detailed study. The Contour measurement method and neutron strain scanning are powerful tools for mapping residual stress and strain fields.

Basics and applications of rapid prototyping medical models

2014 ◽  
Vol 20 (3) ◽  
pp. 256-267 ◽  
Author(s):  
Sushant Negi ◽  
Suresh Dhiman ◽  
Rajesh Kumar Sharma
Keyword(s):  
Rapid Prototyping ◽  
Case Studies ◽  
Three Dimensional ◽  
Medical Model ◽  
Content Type ◽  
Prosthetic Implants ◽  
Medical Sector ◽  
Near Future ◽  
Selection Of

Purpose – This study aims to provide an overview of rapid prototyping (RP) and shows the potential of this technology in the field of medicine as reported in various journals and proceedings. This review article also reports three case studies from open literature where RP and associated technology have been successfully implemented in the medical field. Design/methodology/approach – Key publications from the past two decades have been reviewed. Findings – This study concludes that use of RP-built medical model facilitates the three-dimensional visualization of anatomical part, improves the quality of preoperative planning and assists in the selection of optimal surgical approach and prosthetic implants. Additionally, this technology makes the previously manual operations much faster, accurate and cheaper. The outcome based on literature review and three case studies strongly suggests that RP technology might become part of a standard protocol in the medical sector in the near future. Originality/value – The article is beneficial to study the influence of RP and associated technology in the field of medicine.

Influence of Drawing Straining Path on Hydrogen Damage of Prestressing Steel Wires

2011 ◽  
Vol 488-489 ◽  
pp. 775-778 ◽  
Author(s):  
Jesús Toribio ◽  
Miguel Lorenzo ◽  
Diego Vergara
Keyword(s):  
Residual Stress ◽  
Hydrogen Embrittlement ◽  
Plastic Strain ◽  
Strain Distribution ◽  
Cold Drawing ◽  
Stress And Strain ◽  
Prestressing Steel ◽  
Hydrogen Damage ◽  
Steel Wires ◽  
Hydrogen Accumulation

Residual stress and strain states, produced during cold drawing, play a key role in hydrogen embrittlement (HE) of prestressing steel wires, because of hydrogen accumulation in certain places of the material is affected by stress and strains fields. Taking into account that thedrawingstraining path directly affectsbothresidual stress and plastic strain distribution, the aim of the present paper is to clarify the influence of drawing straining path in the residual state and, consequently, its influence on the HE process of prestressing steel wires.

Analysis of Stress and Strain in the Equal Channel Angular Drawing Process

2006 ◽  
Vol 526 ◽  
pp. 19-24 ◽  
Author(s):  
Javier León ◽  
C.J. Luis-Pérez
Keyword(s):  
Plastic Strain ◽  
Cross Section ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
Wire Drawing ◽  
Stress And Strain ◽  
Drawing Process ◽  
The Cross ◽  
High Plastic Strain ◽  
High Plastic

The equal channel angular drawing (ECAD) process is an innovative method to obtain materials with high plastic strain in a continuous way. This deformation is higher than the deformation achieved by a conventional wire drawing process, for the same reduction of the cross section, so if an adequate thermal treatment is employed later, it could be possible to obtain an initial material with high value that could be useful in conventional manufacturing processes. This process consists in drawing a material through a die where two circular channels intersect at an angle between 90º and 135º. In this work a study using finite element of the plastic strain and the stresses that appear for one aluminium alloy AA-1370 has been carried out. Two ECAD passes have been made, where for the second pass the billet has been rotated 180º along the longitudinal axis. Finally, a calibrated pass has been carried out in order to obtain the billet with homogeneous dimensions in all the cross section. All the simulations have been calculated at room temperature and by using good conditions of lubrication. In order to perform the FEM simulations, a three dimensional geometry has been used. To analyze by FEM the second ECAD pass and the calibration pass, the deformations and stresses achieved in the previous passes have been taken into consideration. This has been done with the aim of achieving higher accuracy. Moreover, a comparative analysis with experimental results has been carried out.

Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate

2000 ◽  
Vol 93 (supplement_3) ◽  
pp. 90-92 ◽  
Author(s):  
Mark E. Linskey
Keyword(s):  
Gamma Knife ◽  
Stereotactic Radiotherapy ◽  
Three Dimensional ◽  
Late Recurrence ◽  
Vestibular Schwannomas ◽  
Tumor Control ◽  
Complication Rates ◽  
Content Type ◽  
Single Fraction ◽  
Fine Print

✓ By definition, the term “radiosurgery” refers to the delivery of a therapeutic radiation dose in a single fraction, not simply the use of stereotaxy. Multiple-fraction delivery is better termed “stereotactic radiotherapy.” There are compelling radiobiological principles supporting the biological superiority of single-fraction radiation for achieving an optimal therapeutic response for the slowly proliferating, late-responding, tissue of a schwannoma. It is axiomatic that complication avoidance requires precise three-dimensional conformality between treatment and tumor volumes. This degree of conformality can only be achieved through complex multiisocenter planning. Alternative radiosurgery devices are generally limited to delivering one to four isocenters in a single treatment session. Although they can reproduce dose plans similar in conformality to early gamma knife dose plans by using a similar number of isocenters, they cannot reproduce the conformality of modern gamma knife plans based on magnetic resonance image—targeted localization and five to 30 isocenters. A disturbing trend is developing in which institutions without nongamma knife radiosurgery (GKS) centers are championing and/or shifting to hypofractionated stereotactic radiotherapy for vestibular schwannomas. This trend appears to be driven by a desire to reduce complication rates to compete with modern GKS results by using complex multiisocenter planning. Aggressive advertising and marketing from some of these centers even paradoxically suggests biological superiority of hypofractionation approaches over single-dose radiosurgery for vestibular schwannomas. At the same time these centers continue to use the term radiosurgery to describe their hypofractionated radiotherapy approach in an apparent effort to benefit from a GKS “halo effect.” It must be reemphasized that as neurosurgeons our primary duty is to achieve permanent tumor control for our patients and not to eliminate complications at the expense of potential late recurrence. The answer to minimizing complications while maintaining maximum tumor control is improved conformality of radiosurgery dose planning and not resorting to homeopathic radiosurgery doses or hypofractionation radiotherapy schemes.

PROMETHEE-based ranking of project managers based on the five personality traits

Kybernetes ◽  
2019 ◽  
Vol 49 (4) ◽  
pp. 1083-1102
Author(s):  
Georgios N. Aretoulis ◽  
Jason Papathanasiou ◽  
Fani Antoniou
Keyword(s):  
Personality Traits ◽  
Questionnaire Survey ◽  
Multicriteria Decision Making ◽  
Project Managers ◽  
Preference Ranking ◽  
Infrastructure Projects ◽  
Public Infrastructure ◽  
Content Type ◽  
The One ◽  
Selection Of

Purpose This paper aims to rank and identify the most efficient project managers (PMs) based on personality traits, using Preference Ranking Organization METHod for Enrichment Evaluations (PROMETHEE) methodology. Design/methodology/approach The proposed methodology relies on the five personality traits. These were used as the selection criteria. A questionnaire survey among 82 experienced engineers was used to estimate the required weights per personality trait. A second two-part questionnaire survey aimed at recording the PMs profile and assess the performance of personality traits per PM. PMs with the most years of experience are selected to be ranked through Visual PROMETHEE. Findings The findings suggest that a competent PM is the one that scores low on the “Neuroticism” trait and high especially on the “Conscientiousness” trait. Research limitations/implications The research applied a psychometric test specifically designed for Greek people. Furthermore, the proposed methodology is based on the personality characteristics to rank the PMs and does not consider the technical skills. Furthermore, the type of project is not considered in the process of ranking PMs. Practical implications The findings could contribute in the selection of the best PM that maximizes the project team’s performance. Social implications Improved project team communication and collaboration leading to improved project performance through better communication and collaboration. This is an additional benefit for the society, especially in the delivery of public infrastructure projects. A lot of public infrastructure projects deviate largely as far as cost and schedule is concerned and this is an additional burden for public and society. Proper project management through efficient PMs would save people’s money and time. Originality/value Identification of the best PMbased on a combination of multicriteria decision-making and psychometric tests, which focus on personality traits.

Influence of the Welded Joint on the Mechanical Behavior of Steel Piles during Static and Dynamic Deformation

2007 ◽  
Vol 345-346 ◽  
pp. 1469-1472
Author(s):  
Gab Chul Jang ◽  
Kyong Ho Chang ◽  
Chin Hyung Lee
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Welded Joint ◽  
Dynamic Deformation ◽  
Three Dimensional ◽  
Steel Structures ◽  
Residual Stress Distribution ◽  
Dynamic Mechanical Behavior ◽  
Steel Piles

During manufacturing the welded joint of steel structures, residual stress is produced and weld metal is used inevitably. And residual stress and weld metal influence on the static and dynamic mechanical behavior of steel structures. Therefore, to predict the mechanical behavior of steel pile with a welded joint during static and dynamic deformation, the research on the influence of the welded joints on the static and dynamic behavior of steel pile is clarified. In this paper, the residual stress distribution in a welded joint of steel piles was investigated by using three-dimensional welding analysis. The static and dynamic mechanical behavior of steel piles with a welded joint is investigated by three-dimensional elastic-plastic finite element analysis using a proposed dynamic hysteresis model. Numerical analyses of the steel pile with a welded joint were compared to that without a welded joint with respect to load carrying capacity and residual stress distribution. The influence of the welded joint on the mechanical behavior of steel piles during static and dynamic deformation was clarified by comparing analytical results

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