M. Anis

Bio: M. Anis is an academic researcher from King Fahd University of Petroleum and Minerals. The author has contributed to research in topics: Finite element method & Welding. The author has an hindex of 3, co-authored 7 publications receiving 47 citations.

Prediction of Flow-Induced Vibrations in Tubular Heat Exchangers—Part I: Numerical Modeling

Abstract: Flow-induced vibrations due to crossflow in the shell side of heat exchangers pose a problem of major interest to researchers and practicing engineers. Tube array vibrations may lead to tube failure due to fretting wear and fatigue. Such failures have resulted in numerous plant shutdowns, which are often very costly. The need for accurate prediction of vibration and wear of heat exchangers in service has placed greater emphasis on the improved modeling of the associated phenomenon of flow-induced vibrations. In this study, the elastodynamic model of the tube array is modeled using the finite element approach, wherein each tube is modeled by a set of finite tube elements. The interaction between tubes in the bundle is represented by fluidelastic coupling forces, which are defined in terms of the multidegree-of-freedom elastodynamic behavior of each tube in the bundle. Explicit expressions of the finite element coefficient matrices are derived. The model admits experimentally identified fluidelastic force coefficients to establish the final form of equations of motion. The nonlinear complex eigenvalue problem is formulated and solved to determine the onset of fluidelastic instability for a given set of operating parameters.

Computational Tradeoff in Modal Characteristics of Complex Rotor Systems Using FEM

Abstract: Modal analysis of complex rotor-bearing systems using the finite element method (FEM) may become controversial when considering the tradeoff between geometric complexity and elastodynamic integrity of the FEM model. In this paper, the modal characteristics of an actual multi-impeller rotor-bearing system with complicated geometry are estimated and verified using two modeling schemes. The first scheme invokes a developed finite element elastodynamic model that accounts for gyroscopic effects, torsional-bending inertia coupling, internal material damping, shear and anisotropic bearings. In this model, the intricate details of the impeller were ignored, and only the inertial properties of the impeller disk are considered. The second scheme employs a general-purpose finite element code, wherein the complicated impeller geometry is included in lieu of ignoring some of the rotational effects and inertia coupling effects. The obtained results shed the light on the tradeoffs involved in modal analysis of complicated rotor systems using the FEM. Comparisons with experimental values showed that the first scheme, which adopts simplified impeller geometry while accounting for all the rotational effects is more accurate in estimating the modal characteristics of such complex rotor-bearing systems.

Estimation of Residual Stress in Spiral Welded Pipe: Regression and Numerical Model

Abstract: Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.Copyright © 2012 by ASME

Optimization of Pipe Repair Sleeve Design

Abstract: For the repair of pipeline defects, repair sleeves are the most widely used method in petro-chemical industry. The objective of this work was to optimize the thickness of non-pressure containing repair sleeve, by refining the existing design practice. Laboratory studies involving instrumentation of small-scaled repair sleeve system coupled with finite element analysis were carried out to refine the design procedure and optimize the thickness of the sleeve. Using a unified approach for finite element modeling, including failure pressure estimation and simulation of sleeve installation pressure, twenty-four cases ranging from 6–60 inches nominal diameter were investigated. In this paper, the details of the optimization approach used in this investigation have been presented.Copyright © 2011 by ASME

Review on finite element analysis of welding deformation and residual stress

Abstract: Welding deformation and residual stress have negative influence on assembly accuracy and service performance. Thermal elastic plastic (TEP) and inherent strain finite element analysis (FEA) methods were used to study this challenge. Basic principle of these two methods was first introduced. The influence of welding process, constraints, solid phase transformation and multi-pass welding on deformation and residual stress was discussed, and computation accuracy and efficiency were summarised. Loading method of inherent strain in inherent strain FEA was analysed, interface element was introduced to simulate effects of the gap on deformation in assembly welding especially for large structures. The future work, including accurately multiscale TEP model, efficiently transient prediction method of large structures, and flexible evaluation software, was planned.

Next generation high‐performance carbon fiber thermoplastic composites based on polyaryletherketones

Abstract: Interest in carbon fiber reinforced composites based on polyaryl ether ketones (PAEKs) continues to grow, and is driven by their increasing use as metal replacement materials in high temperature, high-performance applications. Though these materials have seen widespread use in oil, gas, aerospace, medical and transportation industries, applications are currently limited by the thermal and mechanical properties of available PAEK polymer chemistries and their carbon fiber composites as well as interfacial bonding with carbon fiber surfaces. This article reviews the state of the art of PAEK polymer chemistries, mechanical properties of their carbon fiber reinforced composites, and interfacial engineering techniques used to improve the fiber-matrix interfacial bond strength. We also propose a roadmap to develop the next generation of high-performance long fiber thermoplastic composites based on PAEKs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44441.