Mechanical and Aerospace Engineering, ICMAE2012

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Authors: Siamak Noroozi, John Vinney, Philip Sewell, Rasoul Khandan
Abstract: Ribbed cylindrical Glass Reinforced Plastic (GRP) tanks are currently designed using simplified theory the results of which are then verified by extensive destructive testing. This approach is expensive and can only generate non-optimal design solutions. In addition, there is often a high degree of discrepancy between theoretical and experimental results which necessitates the use of undesirably high factors of safety, which in turn results in the excessive use of material with the concomitant increase in cost, weight and manufacturing time. The primary aim of this investigative research was to develop a more deterministic and accurate design method of predicting the structural integrity and performance of underground cylindrical GRP tanks using non-destructive testing. Linear and non-linear Finite Element Analysis (FEA) techniques, validated against experimental results, were used to analyze a large number of underground ribbed cylindrical GRP tanks. The outcome of which was then expressed in the form of an empirical ‘Design Formula’ which provides a comprehensive solution to ribbed cylindrical GRP tank design for a wide range of tank sizes, laminate lay-ups and material properties. It is intended that the application of this method will eliminate the need for the expensive field tests that are currently required by design codes and standards.
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Authors: Madjid Haddad, Redouane Zitoune, Florent Eyma, Bruno Castanié, Habiba Bougherara
Abstract: In this work, high speed trimming of a multi directional carbon fiber reinforced plastic using a tungsten carbide burr tool is studied. The influence of the machining parameters on both the dust size and surface quality is investigated. A high percentage of dust is found under the theoretical chip size and the surface quality is found to be affected by the cutting parameters. The percentage of inhaled dust reaching the pulmonary alveoli is quantified and found to be very high, it is also found that this percentage is affected by the cutting conditions.
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Authors: Azad Mohammed Ali Saber
Abstract: An analytical elastic-plastic stress analysis is carried out on metal-matrix composite beams of arbitrary orientation, supported from two ends under a transverse uniformly distributed load. The composite layer consists of stainless steel fiber and aluminum matrix. The material is assumed to be perfectly plastic during the elastic–plastic solution. The intensity of the uniform force is chosen at a small value; therefore, the normal stress component is neglected in the elastic-plastic solution. The expansion of the plastic region and plastic stress component of σx are determined for orientation angles of 0, 30, 45, 60 and 90o. Plastic yielding occurs for 0 o and 90 o orientation angles on the lower and upper surfaces of the beam at the same distances from the mid-point. However, it starts first at the lower surface for 30, 45 and 60 o orientation angles.
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Authors: Rasoul Khandan, Siamak Noroozi, John Vinney, Philip Sewell, Mehran Koohgilani
Abstract: A semi-analytical approach for analysis of laminated plates with general boundary conditions under a general distribution of loads is developed. The non-linear equations are solved by the Newton-Kantorovich-Quadrature (NKQ) method which is a combination of well-known Newton-Kantorovich method and the Quadrature method. This method attempts to solve a sequence of linear integral equations. In this paper this method is used to propose a semi-analytical model for buckling of laminated plates. The convergence of the proposed method is investigated and the validation of the method is explored through numerical examples and the results compared with finite element method (FEM). There is a good agreement between the NKQ model and FEM results.
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Authors: Dong Mei Luo, Wen Xue Wang, Qiu Yan Chen, Hong Yang, Ying Long Zhou, Bang Ding Li
Abstract: Multi-step Mori-Tanaka method (MMT) is applied to the estimation of the effective mechanical properties for composites with three-phase randomly distributed aggregates in this paper. The Multi-phase Homogenization Theory (MHT) which is based on mathematical homogenization method and is employed to verify the results of MMT method. Results show that MMT method is reasonable and practicable to predict the effective mechanical properties of composites with several phases, and the Young’s moduli and Poisson’s ratios of each phase may have some effects on the effective mechanical properties of multi-phase composites.
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Authors: Yu Jia Liu, Ying Yan, Hai Qiang She
Abstract: A convenient method to predict the macroscopic elastic performance of composite containing interphase was proposed in this paper. Firstly, a 3-D three-phase micromechanical model with randomly distributed fibers was established with the Moving Window Method (MWM), and the macroscopic elastic properties of T300/914C were predicted using energy method. Secondly, the multiple nonlinear regression correlation between the macroscopic elastic properties and micromechanical characteristic parameters of the interphase was established based on numerical data. Finally, the macroscopic elastic properties of T300/914C containing interphase were predicted using the regression model. Results indicate that the relative error for the longitudinal modulus is within ±1% while it is within ±3.5% for the transverse modulus, and shear modulus.
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Authors: Yang Hou Chen
Abstract: Carbon Fiber-Reinforced Polymer(CFRP) Composite Sheets Have Gained Popularity as a Viable Strengthening Technique for Fractured Concrete Structures. the Behavior of Carbon Fiber Sheet Materials to Cracked Steel Structures Is Quite Different from that of Concrete Structures. More and More Attention Are Paid to Research on Strengthening Steel Structure with Carbon Fiber Sheet. this Paper Presents the Study on the Steel Structure Bonded with Carbon Fiber Sheets. the Infinite Element Analysis Software ANSYS Is Used to Analyze the Effects of Strengthening a Steel Structure. and the Test Results of Crack Specimens Strengthened by Carbon Fiber Sheet Are Given. the Finite Element Results and Test Results Show that the Using of Carbon Fiber Sheet Can Improve Load Bearing of Structure and its Fatigue Life.
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Authors: Akinlabi Esther Titilayo, Madyira Daniel Makundwaneyi, Akinlabi Stephen Akinwale
Abstract: This paper reports on the reconfiguration of a milling machine to produce friction stir welds of aluminium and copper and friction stir processing of 6086 aluminium alloy. Friction stir welding tools were designed and manufactured from tool steel. The tools were inserted into the chuck of the milling machine. A backing plate was also specially designed and manufacturedfrom mild steel to protect the milling machine table and was placed on the bed with the use of T-nuts. The plates were secured firmly on the backing plate with the use of specially designed clamping fixtures. The varied welding speeds and the rotational speeds were achieved using the control system on the vertical milling machine. The reconfigured milling machine was successfully employed to produce friction stir processing of aluminium and friction stir welds of aluminium and copper. An optimum joint strength of 74% was achieved.
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Authors: Hamdi Hentati, Radhi Abdelmoula, Aref Maalej, Khalil Maalej
Abstract: Fracture mechanics has been revisited by proposing different models of quasi static brittle fracture. In this work, the problem of the quasi static crack propagation is based on variational approach. It requires no prior knowledge of the crack path or of its topology. Moreover, it is capable of modeling crack initiation. In the numerical experiments, we use a standard linear (P1) Lagrange finite element method for discretization. We perform numerical simulations of a piece of brittle material without initial crack. An alternate minimizations algorithm is used. Based on these numerical results, we determine the influence of numerical parameters on the evolution of energies and crack propagation. We show also the necessity of considering the kinetic term and the crack propagation becomes dynamic.
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Authors: Hamdi Hentati, Radhi Abdelmoula, Aref Maalej, Khalil Maalej
Abstract: Fracture mechanics has been revisited aimed at modeling brittle fracture based on Griffith viewpoint. The purpose of this work is to present a numerical computational method for solving the quasi static crack propagation based on the variational theory. It requires no prior knowledge of the crack path or of its topology. Moreover, it is capable of modeling crack initiation. At the numerical level, we use a standard linear (P1) Lagrange finite element method for space discretization. We perform numerical simulations of a piece of brittle material without initial crack. We show also the necessity of adding the backtracking algorithm to alternate minimizations algorithm to ensure the convergence of the alternate minimizations algorithm to a global minimizer.
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