Determination of Relation between Elastic Constant and Si ntered Temperature in WC-Ni Composites
In this study we have investigated relation between elasti c constant and sintered temperature in tungsten carbide- nickel composite samples. Determination of elastic properties of materials is based on the transverse and longitudinal wave’s velocities via ultrasonic methods. In this study ultrasonic velocity measurements were measured in the WC-Ni composites. These samples are formed by powder metallurgy and electroless plating. Samples were sintered at temperat ures of 1000 °C, 1100 °C, 1200 °C and 1300 °C with Ar gas atmosphere in tube furnace. In the measuring ultrasonic longitudinal velocity 2 and 5 MHz transducers, ultrasonic transverse velocity 1 and 5MHz transducers have been used. Young Modulus (E) has been calculated by using longitudinal and transverse velocity. A fter we calculated elastic constant, we have investigated relation between sinter ed temperature and elastic constant of samples. A linear relation between sinter ed temperature and elastic constant in samples is observed.
Measurement of elastic constants by the ultrasonic pulse method
Definitions of stress and strain are given in terms of force and differential coefficients of displacement respectively and the generalized form of Hooke's law stated. This defines the elastic constants of a general aeolotropic medium. Special cases of cubic and hexagonal symmetry are considered. The elastic wave equations are derived for plane waves in an infinite aeolotropic solid. The velocities of the three types of wave are given for certain directions in cubic and hexagonal materials. Difficulties may be encountered in propagation of waves along axes other than principal ones due to the oblique path along which the energy travels. This may limit the use of the method to certain directions depending upon the geometry of the specimen. A brief outline of the apparatus used is given and the accuracy which may be achieved is discussed. The method may be applied to polycrystalline materials provided that the grain size is reasonably small.
Thermal-mechanical fully coupled analysis of high-speed angular contact ball bearings
The thermal and mechanical properties of angular contact ball bearings are critical to their operating accuracy and service life. On the basis of the theory of dynamics and frictional heat generation, this work establishes a thermal-mechanical fully coupled model. The high-speed motion characteristics, temperature, and dynamic stiffness are analyzed, and the simulation results are compared with the theoretical calculation and experimental results. Then, the temperature and axial deformation of the bearings under different rotation speeds are analyzed, and the laws of mechanical and thermal characteristics of the bearings are obtained. Results show that an increase in the rotation speed of the inner ring causes the temperature of each component to increase, with the contact area of the balls showing the greatest increase in temperature. An increase in rotation speed also increases the axial deformation of the inner ring.