Blar i Institutt for konstruksjonsteknikk på forfatter "Ren, Xiaobo"
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A method for determining material's equivalent stress-strain curve with any axisymmetric notched tensile specimens without Bridgman correction
Tu, Shengwen; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article, 2017)Large deformation analyses of problems such as plastic forming, ductile fracture with finite element method need a full range of material's equivalent stress-strain curve or flow stress-strain curve. The equivalent ... -
A new method to estimate the residual stresses in additive manufacturing characterized by point heat source
Sun, Li; Ren, Xiaobo; He, Jianying; Olsen, Jim Stian; Pallaspuro, Sakari; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)Residual stress in additive manufacturing (AM) is one of the key challenges in terms of structural integrity and finish quality of printed components. Estimating the residual stress distribution on additively manufactured ... -
A special notched tensile specimen to determine the flow stress-strain curve of hardening materials without applying the Bridgman correction
Tu, Shengwen; Ren, Xiaobo; Nyhus, Bård; Akselsen, Odd Magne; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2017)Structural integrity assessment of weldments requires the input of flow stress-strain curve of each individual material zone. To cope with these challenges, a cylindrical cross weld tensile specimen with a notch located ... -
A bead sequence-driven deposition pattern evaluation criterion for lowering residual stresses in additive manufacturing
Sun, Li; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Peer reviewed; Journal article, 2021)Deposition patterns can significantly influence the distribution and magnitude of residual stress in additively manufactured parts. Time-consuming thermal-mechanical simulations and costly experimental studies are often ... -
CAFE based Multi-scale Modelling of Ductile-to-Brittle Transition of Steel with a Temperature Dependent Effective Surface Energy
Li, Yang; Shterenlikht, Anton; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)It is still a challenge to numerically achieve the interactive competition between ductile damage and brittle fracture in ductile-to-brittle transition (DBT) region. In addition, since two types of fracture occur at two ... -
Constraint effect on the brittle-to-ductile transition of single-crystal iron induced by dislocation mobility
Li, Yang; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article, 2018)The brittle-to-ductile transition (BDT), no matter what the dominated mechanism is, dislocation nucleation or dislocation motion, is not an intrinsic phenomenon of material, and depends not only on the strain rate but also ... -
Determining critical CTOA from energy-load curves with DWTT specimen
Shuai, Jian; Tu, Shengwen; Wang, Junqiang; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2017)Running ductile fracture is one of the most catastrophic accidents of pipelines for natural gas transportation. Crack arrest toughness is important for preventing crack extension to a long distance along pipeline. Critical ... -
Determining the tensile properties of Arctic materials and modelling their effects on fracture
Tu, Shengwen (Doctoral theses at NTNU;2018:269, Doctoral thesis, 2018)The fracture behavior of metallic materials at low temperatures arise great attention among the petroleum industries, due to the potential considerable amount of petroleum and gas resources to be found there. Deep understanding ... -
Effect of heat input on nanomechanical properties of wire-arc additive manufactured Al 4047 alloys
Liu, Siqi; Wan, Di; Peng, Ding; Lu, Xu; Ren, Xiaobo; Fu, Yuequn; Wang, Feng; Li, Yanjun; Zhang, Zhiliang; He, Jianying (Peer reviewed; Journal article, 2022)Heat input is one of the most important process parameters during additive manufacturing (AM). It is of great significance to understand the effect of heat input on the microstructure and nanomechanical properties, as well ... -
Effect of low temperature tensile properties on crack driving force for Arctic applications
Dahl, Bjørn Augdal; Ren, Xiaobo; Akselsen, Odd Magne; Nyhus, Bård; Zhang, Zhiliang (Journal article; Peer reviewed, 2017)Many petroleum companies expand their activities further north towards the Arctic region, resulting in design temperatures down to −60 °C, which is much lower than what is usual for most current petroleum installations. ... -
The Effect of Thermal Residual Stresses on Ductile-to-Brittle Transition of a Welded TMCR Steel by Using CAFE Method
Li, Yang; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Peer reviewed; Journal article, 2019)The effect of residual stress on fracture of materials or structures has been widely studied. However, its influence on ductile-to-brittle transition (DBT), a crucial phenomenon of structural materials, has rarely been ... -
Effect of welding residual stresson fracture
Ren, Xiaobo (Doktoravhandlinger ved NTNU, 1503-8181; 2010:77, Doctoral thesis, 2010)Residual stresses are unavoidable in welded constructions. How to correctly predict residual stresses and assess their effect on structural integrity is a fundamental issue. One of the most difficult aspects in structural ... -
Experimental measurement of temperature-dependent equivalent stress-strain curves of a 420 MPa structural steel with axisymmetric notched tensile specimens
Tu, Shengwen; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2019)Recently, the authors in this paper proposed a correction function to determine material’s equivalent stress-strain curve with axisymmetric-notched tensile specimens. In this study, tensile tests were performed at room ... -
A framework for predicting the local stress-strain behaviors of additively manufactured multiphase alloys in the sequential layers
Liu, Siqi; Lin, Meichao; Wang, Xu; Fu, Yuequn; Ren, Xiaobo; Zhang, Zhiliang; He, Jianying (Peer reviewed; Journal article, 2022)The additive manufacturing (AM) process often results in non-uniform microstructure and different mechanical properties in sequential layers, impacting the overall performance of the AM-ed component. However, it is extremely ... -
Melting cell based compensated design method for improving dimensional accuracy of additively manufactured thin channels
Sun, Li; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Peer reviewed; Journal article, 2020)Powder-bed fusion additive manufacturing technology makes it possible to produce parts with complicated geometry and high accuracy. However, dimensional deviation caused by powder overmelting and dross formation is still ... -
Microstructure and nanomechanical behavior of an additively manufactured (CrCoNiFe)94Ti2Al4 high-entropy alloy
Liu, Siqi; Wan, Di; Guan, Shuai; Fu, Yuequn; Ren, Xiaobo; Zhang, Zhiliang; He, Jianying (Peer reviewed; Journal article, 2021)Recent substantial studies indicate that high-entropy alloys (HEAs) possess superior mechanical performance, including exceptional strength, high creep resistance, etc. However, additive manufacturing (AM), a burgeoning ... -
A multi-barrier model assisted CAFE method for predicting ductile-to-brittle transition with application to a low-carbon ultrahigh-strength steel
Li, Yang; Pallaspuro, Sakari; Ren, Xiaobo; He, Jianying; Kömi, Jukka; Zhang, Zhiliang (Peer reviewed; Journal article, 2020)The conventional micromechanical approaches today are still not able to properly predict the ductile-to-brittle transition (DBT) of steels because of their inability to consider the co-operating ductile fracture and cleavage ... -
Nanoscale creep behavior and its size dependency of a Zr-based bulk metallic glass manufactured by selective laser melting
Liu, Siqi; Chang, Zexin; Fu, Yuequn; liu, yuyu; Lin, Meichao; Ren, Xiaobo; Wang, Wenxian; Zhang, Zhiliang; He, Jianying (Journal article; Peer reviewed, 2022)Nanoscale creep behaviors of metallic glasses (MGs) have gathered considerable interests in recent years, owing to their distinct atomistic mechanisms of plasticity. Additive manufacturing (AM) is a burgeoning technique ... -
Numerical investigation of a novel pattern for reducing residual stress in additive manufacturing
Sun, Li; Ren, Xiaobo; He, Jianying; Zhang, Zhiliang (Journal article; Peer reviewed, 2020)Deposition patterns can significantly affect residual stress distribution in additive manufacturing processes. In this paper, a novel deposition pattern, the S-pattern, is proposed for the additive manufacturing process. ... -
Numerical Study on Ductile-to-Brittle Transition of Steel and its Behavior under Residual Stresses
Li, Yang (Doctoral theses at NTNU;2019: 227, Doctoral thesis, 2019)The transition of fracture mode from ductile to brittle (DBT) is a crucial phenomenon of structural materials, e.g. body centered cubic (BCC) metals, which are normally brittle at low temperatures or high loading rates, ...