Applied Mechanics and Materials Vols. 110-116

Abstract: In the present work, the heat transfer behavior during induction heating of a cylindrical aluminum billet is performed numerically. The heating process is represented by the energy conservation equation where the heat generation during heating is added as a volumetric source term. The evolution of latent heat during melting is also added as a volumetric source term. The continuity and the momentum conservation equations are considered to represent the flow field after melting starts. These governing equations are solved based on the control volume method. The enthalpy update scheme is used for evolution of melt-fraction during heating. The work predicts the evolution of temperature during heating, the distributions of temperature and melt-fraction in the domain. Subsequently, a parametric study is also performed.

Abstract: The equation of large deflection of functionally graded beam subjected to arbitrary loading condition is derived. In this work assumed that the elastic modulus varies by exponential and power function in longitudinal direction. The nonlinear derived equation has not exact solution so shooting method has been proposed to solve the nonlinear equation of large deflection. Results are validated with finite element solutions. The method will be useful toward the design of compliant mechanisms driven by smart actuators. Finally the effect of different elastic modulus functions and loading conditions are investigated and discussed.

Abstract: Mass properties of aerospace vehicle viz Weight, Center of Gravity (Xcg, Ycg, Zcg) & Mass Moment of Inertia (Ixx, Iyy & Izz) are critical inertial parameters which are vital to meet the intended mission objectives. Accurate mass properties measurement is needed for fast maneuvering aerospace vehicles to meet the Control and Guidance requirements within the tolerable limits generated by the System Designer. Mass properties estimation is vital during the configuration design phase of an aerospace vehicle. Assumptions and Constraints during the configuration design, limits the accuracy of estimations making the mass properties measurement mandatory. The mass properties of the aerospace vehicle can be measured by numerous methods, but for achieving high accuracies within the tolerable limits, the measurement system should have advanced technologies and measurement methodologies. Based on the experience, mass properties measurement systems were designed using Load Cells and Cross-Flexural Pivots in two different systems (Weight and CG in System-1, MOI in System-2), which have limited accuracy and also involves tedious external measurements. Adopting Air-Bearing (T / H / Spherical shape) supported with accurate sensors using Inverted Torsion Pendulum method, Multiple Point Weighing method and a proper measurement methodology, enhances the accuracy of the measurement system. Usage of spherical bearing yields a better accurate system but has the difficulty in realization of the system indigenously, whereas use of T or H-shape bearing is a feasible solution for achieving the desired accurate mass properties specifications. This paper gives an insight into to the product design aspects to be considered for realization of accurate mass properties measurement system.

Abstract: In order to predict a turbulent flow around a triangular cylinder a high Reynolds number of 45000 is done in the numerical simulation. In this simulation both steady and unsteady vortex shedding is predicted and various time steps. The numerical method used in this simulation is Reynolds Stress model. For steady and unsteady solution velocity contours and velocity vector plots is to be predicted for the vortex shedding behind the triangular cylinder.

Abstract: Deformation of Titanium alloys close to optimal superplastic condition i.e. near superplastic regime of deformation leads to significant change in microstructures.VT-9 titanium alloy was used in order to find out those parameters of microstructure which are varying significantly during near superplastic regime of deformation. Tensile tests were carried out at 930°C up to fracture with a constant strain rate of 5*10^-4 s^-1 and a jump wise varying strain rate of 1*10^-4 s^-1 & 5*10^-4 s^-1 .The microstructural parameters of both air-cooled and water quenched portion i.e. size of alpha phase, percentages of alpha phase and parameter of non-uniaxiality of alpha phase were found to change significantly during near superplastic regime of deformation. It has been found that in the near superplastic regime of deformation percentage of α-phase decreased from 90% to 13%. As the β-transus temperature of this alloy is 970°C, this significant change in percentage of α-phase is attributed to deformation induced phase transformation. Optical microscopes, micro Vickers hardness test, XRD, FESEM have been used to characterize the microstructure of the material.

Abstract: This assay analyzes the docking of BLRU for the SG-Ⅲ Laser Facility, where centering and collision issues are pointed out as the key technologies for BLRU docking monitoring. The centering technology mainly transforms the three-dimensional problem into two-dimensional one, adopting the characteristic of machine version capturing to analyze the position and posture of BLRU. The collision monitoring technology mainly takes advantage of the principle that power is generated in the collision during the process of assembly and calibration. Monitoring the forces from each direction, the degree of indirect response to the collision, returning feedback to the docking platform after measurement data is analyzed, and amending the docking trajectory of the BLRU in time can achieve the light collision docking during the full process of BLRU.

Abstract: In this paper, a remote mine-gas concentration real-time detecting system is realized, which is cored at the MSP430F247 single chip and the Siemens TC35GSM module. The author introduces the system structure, functional principle and specific implementation scheme in details. Besides, the real-time collection of gas concentration, high-speed and accurate analysis on the data, setting and exceeding standard alarm of gas concentration, remote date transportation and good human-computer interaction displaying function can be realized through the making and debugging of the prototype.

Abstract: This paper focuses on measuring of an object’s three axes dimensions (X Y&Z) simultaneously. The instrument is called “3D syskevis metrisis” and this name has been derived from Greek words which means 3D measuring device. This instrument has a least count of 0.02mm and has the range of 15cm in all the three axes (X, Y & Z respectively). The object to be measured is not moved after it is initially placed on the base part of the instrument and there is no chance for error due to the mishandling of the object because the DOF (degree of freedom) of the object is arrested with the syskevis scale and the time for measuring the object is less when compared to the time taken by a Vernier caliper. The main advantage of this instrument is its low cost which is around RS8500.Thus by using this instrument we can measure the dimensions of small objects without moving the object after it is placed on the instrument with high accuracy and low cost.

Abstract: —In this work, comparative study for dynamic response is carried out for optimized single link flexible robotic manipulator under various types of excitations. Manipulator is considered as an Euler-Bernoulli beam and shape is optimized for circular area of cross-section. Finite element method is used to obtain fundamental frequency and sequential quadratic programming (SQP) is used for its maximization.

Abstract: In this paper, a robot design suitable for swarm based security system is presented. First, a possible layout for swarm based security system is conceptualized and literatures related to mobile robot design are reviewed. Second, a set of conceptual designs for the swarm robot are evolved and discussed. Third, expressions are arrived for weight, rolling resistance, obstacle crossing ability and amount of slip based on robot geometric parameters. Fourth, the obstacle crossing ability for rear wheel driven and rear wheel driven robots are investigated. Fifth, a prototype is made and the analytical expressions arrived are verified experimentally. Sixth, the drive power required for the direct drive robot is determined. Finally, based on weight, number of actuators, type of drive, type of wheels used, rolling resistance, and obstacle crossing ability an appropriate robot design is selected.