The main requirements for machine tool structures are higher damping, stiffness, and dimensional stability and low thermal expansion coefficient. Compared with cast iron (CI), stone-based polymer composite provides improved damping characteristics, because of which it is being considered as an alternate material for machine tool structures in recent research. In this work, process parameters of epoxy granite (EG) composite were optimized using the technique for order preference by similarity to ideal solution (TOPSIS) method to obtain optimum strength characteristics. The effect of process parameters, namely curing time (A), aggregate mass fraction (B), aggregate size mix (C), curing temperature (D), and stirring speed (E) on static and dynamic characteristics of EG composite were investigated. An analysis of variance test was performed to identify the significant process parameters with a confidence level of 95 %. The predicted process parameters are verified through confirmatory tests, which showed an improved preference value of 0.0948. To obtain optimum strength properties, the recommended optimum process parameters are found to be A = 12 h, B = 0.8, C = aggregate size mix 1, D = 40°C, and E = 90 r/min. Experimental modal analysis also revealed that the damping factor of EG composite with aggregate mass fraction B = 0.8 is 10 times higher than that of CI. Morphological analysis of EG composite using a field emission scanning electron microscope showed that granite aggregates are uniformly distributed with better epoxy bonding characteristics.

Polymer concrete or epoxy granite is now becoming more popular for beds, bases, and other structures of precision machine tools, owing to its excellent damping characteristics. In order to realize the same static rigidity as that of the cast-iron structures, steel-reinforced epoxy granite (SREG) structures are being used. The vast differences in the thermal properties of steel and epoxy granite (EG) are likely to cause higher magnitudes of thermal error. The objective of this work is to investigate the thermal behavior of a CNC lathe built with an SREG bed and compare its performance with the lathe with cast iron bed. Experimental and numerical investigations have been carried out under cross feed drive (CF) idle running conditions to determine the TCP deformation. The results reveal that the thermal error in the CNC lathe with SREG bed is 1.68 times that of the lathe with CI bed at 20ºC and 1.8 times at 40ºC environmental temperature variation chamber (ETVC) conditions. It could be identified that the heat generated in the CF is conducted to the steel guideways embedded in the SREG bed, but further heat transfer to the EG portion of the bed is impeded and hence the heat accumulation that occurs in the guideways leads to higher magnitude of thermal error. The experimentally validated numerical model is used to extend the investigations to study the effect of the idle running of the longitudinal feed drive (LF), and combined cross and longitudinal feed drives, on the thermal behavior of the lathe.

Wear is the major parameter for various applications in automobile and aeronautical industries. Various researches are going on to improve the wear by either alloying the material or using the composite material. Current study focuses on wear improvement through composite material with aluminium as matrix and cenospheres as re-inforcement. The abrasive wear behavior of cenosphere particle reinforced aluminium alloy (AA) 6063 was investigated using pin-on-disc technique. Aluminium -cenosphere metal matrix composite was fabricated by adding various percentages of cenosphere particles using stir casting technique and its abrasive wear behavior was compared with AA6063. The uniform distribution of particles was ensured with the help of scanning electron microscopy (SEM).

The roof slab of the nuclear reactor supports all the components and sub-systems. Roof slab needs to resist the seismic loads in accordance with load-carrying criteria. The static stress analysis of the reactor roof slab reveals that high-stress concentration was present in the pump penetration shell (PPS) which supports the primary sodium pump. This paper presents the assessment of collapse load and optimization of pump penetration shell, through the reliability approach, accounting for material nonlinearity, geometrical nonlinearity and randomness in loading. In addition to that, the load-carrying capacity of PPS was determined considering two different materials, viz., IS2062 and A48P2. The design of experiments (DoE) was formulated considering the flange angle and flange thickness as parameters. An empirical model for load function was formulated from the results of the collapse load obtained for various combinations of design parameters. The above function was used to perform the reliability-based geometry optimization of PPS of the roof slab.