iosr-JMCE   Volume-9 ~ Issue-5

Abstract: During the life of a structure impact by foreign objects can be expected to occur during manufacturing, service and maintenance operations. An example of in service impact occurs during aircrafts takeoffs and landing. During the manufacturing process or during maintenance tools can be dropped on the structure, in this case the impact energy is small, laminated structures are more susceptible to impact damage often cannot be detected by visual inspection. This internal damage can severe reductions in strength and further reductions occur under the load. Therefore the effects of foreign object impact on composite structure must be understood and proper measures should be taken in the design process to account for expected events. Concerns about the effects of impact on the performance of composite structures have been a factor in limiting the use of composite materials. For these reasons the problem of impact has received considerable attention in the literature. The process of impact damage initiation and growth, and identify the governing parameters are important for the formulation of numerical models for damage prediction, for designing impact resistant structures and for developing improved material systems. An important aspect of a model for predicting the impact dynamics is to accurately describe the behavior of the target under impact loading conditions. For some simple cases the structural loading can be modeled by a simple spring-mass system or by using the quasi-static behavior and considering the energy balance for a system. But in general more sophisticated beam, plate or shell theories are required to model the structure. .

Keywords: FEA, Low-velocity impact, LS DYNA, Modeling, Simulation

[1]. IK-HYEON CHOI, "LOW-VELOCITY IMPACT ANALYSIS OF COMPOSITE LAMINATES UNDER INITIAL IN-PLANE LOAD" COMPOSITE STRUCTURES 86 (2008) 251–257
[2]. Shokuhfar.A, "Analysis and optimization of smart hybrid composite plates subjected to low-velocity impact using the response surface methodology (RSM)" Thin-Walled Structures 46 (2008) 1204– 1212
[3]. Tiebreak .R.a, Bachene.M b, Rechak S.c, Necib.B "Damage prediction in composite plates subjected to low velocity impact" Composite Structures 83 (2008) 73–82
[4]. SADIGHI. M, H. POURIAYEVALI, SAADATI.M "Response of fully backed sandwich beams to low velocity transverse impact" World Academy of Science, Engineering and Technology 36 2007
[5]. Hosur.M.V, "Studies on the low-velocity impact resip/;ponse of woven hybrid composites" Composite Structures 67 (2005) 253–262
[6]. Ik Hyeon Choi, "Low-velocity impact analysis of composite laminates using linearized contact law" Composite Structures 66 (2004) 125–132
[7]. Shiuh-Chuan Her, "The finite element analysis of composite laminates and shell structures subjected to low velocity impact" Composite Structures 66 (2004) 277–285
[8]. Giovanni Belingardi, "Low velocity impact tests of laminate glass-fiber-epoxy matrix composite material plates" International Journal of Impact Engineering 27 (2002) 213–229
[9]. Krishnamurthy.K.S, "A parametric study of the impact response and damage of laminated cylindrical composite shells" Composites Science and Technology 61 (2001) 1655–1669
[10]. Parhi.P.K, Bhattacharyya.S.K and Shina.P.K:"Failure analysis of multiple delaminated composite plates due to bending and impact" Bull. Mater. Sci., Vol. 24, No. 2, April 2001, pp. 143–149

Abstract: Optimization of operating parameters is an important step in machining, particularly for operating unconventional machining procedure like Wirecut Electro Discharge Machining. Since wire-cut EDM has experienced explosive growth in application users demand and need maximum productivity and through-put, increased accuracy, and predictable performance. Also machines and job requirements vary greatly, which can make selection of the correct operation parameters a daunting task. As a result, experimentation is necessary if optimum results are to be achieved. Although this reference is not intended to be all-encompassing, it should be a useful guide for selection of parameters. A suitable selection of machining parameters for the process relies heavily on the operator's technologies and experience and they do not provide the optimal machining conditions. In every manufacturing process, material removal rate needs to be maximized while controlling quality by controlling electrode wear rate. In this work, an attempt has been made to optimize the machining parameters for minimum electrode wear rate and maximum material removal rate in WEDM process. Experiments were performed under different cutting conditions of Wire feed (WF), wire tension (WT), discharge current of the machine and discharge voltage (V). Experiments were executed as per Taguchi's L-9 orthogonal array. The output responses were optimized using signal-to-noise (S/N) ratio in addition to Desirability function approach to convert a multi objective optimization problem to a single objective optimization problem.

Keywords: Wire Electro Discharge Machining,WEDM, Electrode wear rate, Material removal Rate, Taguchi's orthogonal array, S/N Ratio,Desirablity Function Approch , Wire Feed

[1] Yih-fong Tzeng, FU-chen Chen (2007), "Multi-objective optimization of high speed electrical discharge machining process using a Taguchi fuzzy based approach", Materials and Design, Vol. 28, pp. 1159-1168.

[2] S Kumar, TP Singh (2007), "A comparative study of the performance of different EDM electrode materials in two dielectric media", (IE) (I) Journal-PR, Vol. 8, PP. 3-8.

[3] SK Saha (2008), "Experimental investigation of the dry electric discharge machining (Dry EDM) process", M. Tech. Thesis, IIT Kanpur, Kanpur 208016, India.

[4] GKM Rao, GR Janardhana, DH Rao, MS Rao (2008), "Development of hybrid model and optimization of metal removal rate in electrical discharge machining using Artificial Neural Networks and Genetic Algorithm", ARPN Journal of Engineering and Applied Sciences, Vol. 3, No. 1, pp. 19-30.

[6] H Singh, R Garg, (2009), "Effects of process parameters on material removal rate in WEDM", Journal of Achievement in Materials and Manufacturing Engineering, Vol. 32, No. 1, pp. 70-74.

[7] MK Pradhan, CK Biswas (2009), "Modeling and analysis of process parameters on surface roughness in EDM of AISI D2 tool steel by RSM approach", International Journal of Engineering and Applied Sciences,Vol. 5, No. 5, pp. 346-351.

[8] AKM Asif Iqbal, Ahsan Ali khan (2010), "Modeling and analysis of MRR, EWR and surface roughness in EDM milling through Response Surface Methodology", American Journal of Engineering and Applied Science, Vol. 3,No. 4, pp. 611-619.

[9] NM Abbas, DG Solomen, MF Bahari, (2007), A Review on Current research trends in Electrical Discharge Machining (EDM), International Journal of machine Tools and Manufacture, Vol. 47, pp. 1214-1228.

[10] HS Payal, R Choudhury, S Singh (2008), "Analysis of electro discharge machined Surfaces ofEN-31 tool steel",Journal of Scientific and Industrial Research, Vol.67, pp. 1072-1077.

Abstract: Composite cylindrical shells are being used in submarine, underground mines, aerospace applications and other civil engineering applications. Thin cylindrical shells are more prone to fail in buckling rather than material failure. An experimental study on buckling of glass fiber reinforced plastics layered composite cylindrical shells under displacement and load controlled static axial compression are reported The experimental results are compared with general purpose finite element program (ANSYS). Limit point loads evaluated for geometric imperfection magnitudes shows an excellent agreement with experimental results which clearly indicates the confidence gained on the numerical results presented. Present study finds direct application to qualitatively investigate the influence of geometric imperfection on other advanced grid-stiffened structures.

Keywords: Composite, cylindrical shell, finite element, geometric imperfection, nonlinear buckling

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