13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Finite element analysis of erosive wear for offshore structure Z.G. Liu1*, S. Wan1, V.B. Nguyen1, Y.W. Zhang1 1 Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, 138632, Singapore * Corresponding author: liuzh@ihpc.a-star.edu.sg Abstract Erosive wear, which is a complex material damage process caused by particle impacting on the surface of equipments, has been a major concern in oil & gas industry. In this work, we employ three-dimensional finite element (FE) method to investigate the erosion process under multiple particle impacts with both spherical and irregular non-spherical particles. We take into account both elastic-plastic material behaviors, which is described by Johnson-Cook visco-plastic model, and material removal, which is governed by the Johnson-Cook failure model. The relationships between the erosion rate and the particle velocity and impact angle are obtained and compared with published data. The implications of the current simulation results are also discussed. Keywords Erosion rate, Solid particle impact, Finite element analysis (FEA), Failure 1. Introduction Erosion wear, which arises from solid particle impacting, is one of the major failure modes that cause offshore structure damage. Erosion is found in a wide range of equipments in offshore industry, in which solid particles are entrained into fluid flow in the operating process, such as gas turbine, oil & gas pipeline, drilling platforms, etc [1]. This damage mode affects not only operating process, but also safety and economics as well. Therefore, it is necessary to find a good predictive method to accurately predict the erosion rate for offshore equipment. The erosion mechanism is different in ductile and brittle materials. A number of studies have been performed to reveal the erosion mechanisms of ductile and brittle materials [2-6]. It is now known that brittle materials erode by cracking and chipping, while ductile materials erode by a sequence of micro-cutting, forging and fracture, etc [7]. Hence, erosion rate and mechanism are highly dependent on material types. So far, several experimental methods have been developed to determine the eroded volume of a material. However, the experimental data found in the literature often refer to a particular material without specifying their properties and operating conditions. Therefore, the experimental erosion rate for the same material reported by different authors can differ greatly [8]. Numerical simulations, such as the Finite Element Method (FEM), have also been used to characterize erosion wear. Previously, 2D models were mainly used to investigate the influencing parameters of erosion wear. However, 2D simulation cannot correctly consider the effects of multi-particle erosion. Hence, 3D FEM models have been often used to study the erosion process. For example, Alman et al. [9] studied erosion behavior of both brittle and ductile materials, and concluded that the impact angle is important for erosion mechanism: A ductile material exhibits the maximum erosion rate at an impact angle of about 20-40°, while a brittle material shows the maximum erosion rate at an impact angle of 90°. ElTobgy et al. [6] studied erosion wear process using multiple impacts with perfect spherical particles, and pointed out that single-particle impact is insufficient, and three or more particles are needed to simulate the erosion process. Subsequently, Wang et al. [7] performed finite element simulations on erosion wear with 100 sphere particles and analyzed the erosion rate of both ductile and brittle materials, and compared their simulation results with that using other computational models. In this study, we perform three-dimensional FEM simulations using the Johnson-Cook models to study the erosion rate for multiple impacts with both spherical and non-spherical solid particles on a deformable substrate. The main objective is to analyze the erosion rate of different particles with
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