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  • Open Access


    A Methodology to Reduce Thermal Gradients Due to the Exothermic Reactions in Resin Transfer Molding Applications

    Aouatif Saad1,*, Mohammed EL Ganaoui2

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 95-103, 2023, DOI:10.32604/fdmp.2023.022014

    Abstract Resin transfer molding (RTM) is among the most used manufacturing processes for composite parts. Initially, the resin cure is initiated by heat supply to the mold. The supplementary heat generated during the reaction can cause thermal gradients in the composite, potentially leading to undesired residual stresses which can cause shrinkage and warpage. In the present numerical study of these processes, a one-dimensional finite difference method is used to predict the temperature evolution and the degree of cure in the course of the resin polymerization; the effect of some parameters on the thermal gradient is then analyzed, namely: the fiber nature,… More >

  • Open Access


    Fatigue Crack Propagation Analysis of Orthotropic Steel Bridge with Crack Tip Elastoplastic Consideration

    Ying Wang1,*, Zheng Yan1, Zhen Wang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.2, pp. 549-574, 2021, DOI:10.32604/cmes.2021.014727

    Abstract Due to the complex structure and dense weld of the orthotropic steel bridge deck (OSBD), fatigue cracks are prone to occur in the typical welding details. Welding residual stress (WRS) will cause a plastic zone at the crack tip. In this paper, an elastoplastic constitutive model based on the Chaboche kinematic hardening model was introduced, and the extended finite element method (XFEM) was used to study the influence of material elastoplasticity and crack tip plastic zone on the law of fatigue crack propagation. By judging the stress state of the residual stress field at the crack tip and selecting different… More >

  • Open Access


    Prediction of Melt Pool Dimension and Residual Stress Evolution with Thermodynamically-Consistent Phase Field and Consolidation Models during Re-Melting Process of SLM

    Kang-Hyun Lee1, Gun Jin Yun1,2,*

    CMC-Computers, Materials & Continua, Vol.66, No.1, pp. 87-112, 2021, DOI:10.32604/cmc.2020.012688

    Abstract Re-melting process has been utilized to mitigate the residual stress level in the selective laser melting (SLM) process in recent years. However, the complex consolidation mechanism of powder and the different material behavior after the first laser melting hinder the direct implementation of the re-melting process. In this work, the effects of re-melting on the temperature and residual stress evolution in the SLM process are investigated using a thermo-mechanically coupled finite element model. The degree of consolidation is incorporated in the energy balance equation based on the thermodynamically-consistent phase-field approach. The drastic change of material properties due to the variation… More >

  • Open Access


    Review on the Prediction of Residual Stress in Welded Steel Components

    Junyan Ni1, Xincun Zhuang2, 3, Magd Abdel Wahab4, 5, *

    CMC-Computers, Materials & Continua, Vol.62, No.2, pp. 495-523, 2020, DOI:10.32604/cmc.2020.08448

    Abstract Residual stress after welding has negative effects on the service life of welded steel components or structures. This work reviews three most commonly used methods for predicting residual stress, namely, empirical, semi-empirical and process simulation methods. Basic principles adopted by these methods are introduced. The features and limitations of each method are discussed as well. The empirical method is the most practical but its accuracy relies heavily on experiments. Mechanical theories are employed in the semi-empirical method, while other aspects, such as temperature variation and phase transformation, are simply ignored. The process simulation method has been widely used due to… More >

  • Open Access

    Study on Residual Stresses in Unidirectional Flax Fiber/ Vinyl Ester Composites by XRD Technique

    Shanshan Huo, Chad A. Ulven*

    Journal of Renewable Materials, Vol.5, Suppl.1, pp. 106-116, 2017, DOI:10.7569/JRM.2017.634136

    Abstract The development of flax fiber reinforced polymer composites with improved properties has been increasingly studied by many researchers because of their sustainability. However, the effects of thermal residual stresses on the interfacial properties of flax composites have not been evaluated or very well understood. In this study, the thermal properties of flax, vinyl ester matrices and their composites were accessed by different techniques, including thermomechanical analyzer, dynamic mechanical analyzer, and X-ray diffraction combined with aluminum particles. The effects of thermal properties of flax fibers and vinyl ester resin systems on the mechanical properties of their biocomposites were studied. The theory… More >

  • Open Access


    Relaxation of Residual Stress under Fatigue Load Described in Terms of Cyclic-Plastic Deformation Model

    S. Kwofie1

    Structural Durability & Health Monitoring, Vol.8, No.4, pp. 295-306, 2012, DOI:10.32604/sdhm.2012.008.295

    Abstract Fatigue life of components may be enhanced by mechanical surface treatments, such as shot penning, which induce compressive residual stresses in the component's surface. Under cyclic/fatigue loads, however, relaxation of the residual stress may occur thus, reducing the optimum benefit of the surface treatment. For health monitoring / life prediction under such conditions it is important to be able to assess stress relaxation in real-time. However, the phenomenon of cyclic relaxation of residual stress is not well understood and its tracking during component operation is a technical challenge. By means of cyclic plastic deformation model and the Matlab/Simulink Program cyclic… More >

  • Open Access


    Fatigue Assessment of Notched Steel Including Residual Stresses Obtained by the Rolling Process

    G. Nicoletto1, A. Saletti2

    Structural Durability & Health Monitoring, Vol.8, No.2, pp. 131-148, 2012, DOI:10.3970/sdhm.2012.008.131

    Abstract Fatigue strengthening of fillets by deep rolling is finding increased application for example in engine crankshaft production for functional and economical reasons. A fatigue design method aimed at exploiting the residual stresses that develop at a notched part following the rolling process is proposed. It is based on the superposition of residual stresses obtained by elastic-plastic FE simulation of the rolling process and the cyclic elastic stresses within a Haigh diagram framework. The fatigue design method is assessed using the experimental evidence obtained by testing notched specimens made of 30NiCrMo12 steel subjected to different rolling process parameters. More >

  • Open Access


    Crack Growth Simulation in Integrally Stiffened Structures Including Residual Stress Effects from Manufacturing. Part II: Modelling and Experiments Comparison

    S.M.O. Tavares1, S.M. Häusler2, P.M. Baiz3, P.M.S.T. de Castro1, P. Horst2 , M.H. Aliabadi3

    Structural Durability & Health Monitoring, Vol.7, No.3, pp. 191-210, 2011, DOI:10.3970/sdhm.2011.007.191

    Abstract This article is the second part of a two parts paper which presents, compares and discusses the different crack growth simulation models which were introduced for fatigue crack growth assessment during the DaToN project. In the first part, different simulation approaches were applied to determine a calibration of the stress intensity factors as a function of the crack length for a two stiffeners panel with a central crack. Due to the residual stress field promoted by the different manufacturing processes, its influence was included in the numerical models to determine the stress intensity factors. In this second part, the stress… More >

  • Open Access


    Crack Growth Simulation in Integrally Stiffened Structures Including Residual Stress Effects from Manufacturing. Part I: Model Overview

    S.M. Häusler1, P.M. Baiz2, S.M.O. Tavares3, A. Brot4, P. Horst1, M.H. Aliabadi2, P.M.S.T. de Castro3, Y. Peleg-Wolfin4

    Structural Durability & Health Monitoring, Vol.7, No.3, pp. 163-190, 2011, DOI:10.3970/sdhm.2011.007.163

    Abstract This article represents the first part of a two-part article which presents, compares and discusses the different crack growth simulation models which were introduced for fatigue crack growth assessment during the DaToN project. The project was funded by the EC within the 6th framework program and was specifically devoted to investigate innovative manufacturing techniques for metallic structures with special focus on the effects of residual stresses on the fatigue crack growth and residual strength behaviour. Within this first part the different simulation approaches, including the residual stress modelling approaches will be introduced and stress intensity factor results will be presented… More >

  • Open Access


    Influence of Structural Defects on the Beneficial Effect of Autofrettage

    S. Hadidi-Moud1,2, H. Makari1

    Structural Durability & Health Monitoring, Vol.6, No.2, pp. 113-122, 2010, DOI:10.3970/sdhm.2010.006.113

    Abstract A comprehensive numerical study has been carried out to investigate and to explore the impact of the presence of part through surface cracks of various size and orientation in a thick welded ferritic steel cylindrical vessel, on the beneficial effect of autofrettage loading. It is well known that autofrettage loading enhances the load carrying capacity of defect free pressure vessels. The results of this study suggest that in presence of cracks, the localised near crack tip residual stress fields interact with in service stresses and influence the enhancement in load carrying capacity of autofrettaged vessel. Furthermore it is concluded that… More >

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