PRAKASH, C. P. S., RANGANATH, B. J.: Productivity improvement by application of WEDM as a super finishing operation 237 MUSIL, M., ÚRADNÍČEK, J.: Numerical comparison of car suspension control strategies employing a continuous semiphysical MR damper model 243 AIT RIMOUCH, H.---MARFOUK, A.: An efficient method for reducing the effects of modal truncation for dynamic reanalysis problems 257 RAO, M. V., RAO, K. M., RAJU, V. R. CH., MURTHY, V. B. K., RAJU, V. V. S.: Three-dimensional finite element analysis of adhesively bonded single lap joints in laminated FRP composites subjected to combined loading with C-F end conditions 277 KUMAR, A., MAHESHWARI, S., SHARMA, C., BERI, N.: Performance evaluation of silicon abrasive in electrical discharge machining of EN 24 steel based on Taguchi method 289
C. P. S. PRAKASH, B. J. RANGANATH
Wire electrical discharge machining (WEDM) is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. Parts having sharp edges that pose difficulties to be machined by the main stream machining processes can be easily machined by WEDM process. Since the introduction of the process, WEDM has evolved as a simple means of making tools and dies to the best alternative of producing micro-scale parts with the highest degree of dimensional accuracy and surface finish. This paper deals with machining different materials like En8, En31 and HCHC at different working conditions, studying the metal removal rate (MRR) and surface roughness (SR). From the available literature, it is learnt that application of WEDM for machining different materials is studied but no work is done to study WEDM as a super finishing operation. Hence the experimentation includes metallurgical evaluation with micrograph analysis. The surface characteristic of HCHC material is studied for multi-pass machining to study the effect of it on the surface finish obtained. Machining has been done on Fanuc Robocut a-c WEDM Machine. Mahr Gmbh Perthometer M2 is used for SR measurements. JSM-840A (JEOL, Japan) Scanning Microscope is used for micrographs, and Link ISIS Oxford Instruments, UK, for EDX analysis.
MILO MUSIL, JURAJ ÚRADNÍČEK
The paper presents a study of a semi-active adaptive control algorithm through numerical simulation where the adaptive control is compared to the skyhook control, active LQR, semi-active LQR, and passive suspension. A continuous semi-physical hysteretic magneto-rheological (MR) damper model is proposed so that sensitivity of the system variables with respect to the control variable can be evaluated for the purpose of employing the adaptive control algorithm based on the gradient search method. This study includes discussions of the MR damper model set-up, 1/4-car suspension model set-up, controller set-up and dynamic analysis approach. The effectiveness of all controllers and passive suspension is demonstrated through simulations.
HAMMOU AIT RIMOUCH, A. MARFOUK
The effects of modal truncation are often encountered in dynamic problems. This study is a contribution to reduce them in structural dynamic modification problems.
The paper develops an efficient modal reanalysis technique, less onerous and more precise, to evaluate the natural frequencies and mode shapes of a modified structure. The originality lies in the structure of the obtained formula, where attention is focused on the contribution of the unknown modes. Such a contribution can be either calculable, for a finite element model, or identifiable starting from an experiment model tests. Numerical tests illustrating the effectiveness of this method are presented. High quality results can be obtained, even if the introduced modifications are very important.
M. VENKATESWARA RAO, K. MOHANA RAO, V. RAMA CHANDRA RAJU, V. BALA KRISHNA MURTHY, V. V. SRIDHARA RAJU
The present investigation deals with the thermo-elastic analysis of adhesively bonded single lap joint in laminated fibre reinforced plastic (FRP) composites using three-dimensional theory of elasticity-based finite element method (FEM). The finite element model is validated with the available results in the literature for the longitudinal loading of a single lap joint (SLJ) made of especially orthotropic laminates and is extended for the analysis of a single lap joint made of generally orthotropic laminates subjected to combined axial and non-linear temperature loads. The out-of-plane normal and shear stresses are computed at the interfaces of the adherents and adhesive, and at mid-surface of the adhesive. The results of the present analysis reveal that the three-dimensional stress analysis is required for the analysis of single lap joint in laminated FRP composites.
ANIL KUMAR, SACHIN MAHESHWARI, CHITRA SHARMA, NAVEEN BERI
In this paper an attempt has been made to find optimal process parameters of abrasive mixed electrical discharge machining (AEDM). Taguchi methodology has been adopted for planning and analysing the experiments for optimising the multiple performance characteristics. The process input parameters, viz. concentration of silicon in dielectric fluid, current, pulse-on time, duty factor were chosen to study process performance in terms of material removal rate (MRR) and surface roughness (SR). The investigations result show that with addition of silicon abrasive powder (2 g l-1) in kerosene dielectric fluid, material removal rate improves by 23 % and surface roughness is reduced by 35 %. The optimum process conditions as suggested by the present study are verified by conducting confirmation experiments.