---

Micromechanical resonators are miniature devices that vibrate at high frequencies. Nowadays, with the recent advances in micro-electro-mechanical systems (MEMS) fabrication technology, micromechanical resonators are used widely in sensors, wireless communication and navigation systems. The commonly encountered energy loss mechanisms in micromechanical resonators include air damping, thermoelastic dissipation and anchor loss. In this paper, with regard to the dominated quality factor by anchor loss in some important applications including oscillators, electrical filters and gyroscopes, the closed-form expression is obtained for anchor loss quality factor in the plunging-mode vibrations of micromechanical rectangular-plate resonator with two support beams. The findings are validated by comparing with experimental data. As far as there is an acceptable match between the analytical and experimental results, the proposed model is confirmed. The results also show that the anchor loss quality factor increases with increasing substrate thickness. Moreover, a new design is proposed to enhance the anchor loss quality factor in the plunging-mode vibrations of micromechanical rectangular-plate resonators. For this purpose, the conventional support beams are replaced with T-shaped support beams. Besides, the results show that the anchor loss quality factor at the same resonant frequency is enhanced about 1.5 times.

---

Copper clad aluminum composite wire used in wire and cable industry is an applied product. This product must be manufactured according to standard ASTM B566. According to this standard the connection between the layers is one of the quality parameters. Interlayer pressure during the production process, plays an important role in the quality of connection between two layers. The effects of important wire drawing parameters, including a half-angle dies, reduction ratio and coefficient of friction on the interlayer pressure were discussed by slab methods. After samples making, test of wire drawing process was conducted to determine the force with three modes of dry friction, oil lubrication and grease lubrication. There was good agreement between experimental and analytical methods. With Increase in friction coefficient of interlayer the interlayer pressure will increase. With increase in half angle of die, the interlayer pressure was increase significantly. So that, by increasing the half angle of die from 5 to 75 degree, the interlayer pressure increases about 3 times. Also, with increase in reduction of area the interlayer pressure was increase. But, it was found that the friction coefficient of die does not have a role in interlayer pressure changes.

---

Bimetallic Copper clad aluminum according to standard ASTM B566 can be used in telecommunication networks and signal transmission. The quality of this product in terms of bonded layer’s, in reference standard is important. The interlayer pressure affected during the drawing process on the quality of bonded layer’s. Sample of Bimetallic wire in 9.5 mm diameters was produced by Copper clad with thickness of 0.45 mm. Bimetal wire formed by wire drawing process with 6.2% reduction in area. In this study the effect of tow parameters of wire drawing process: semi die angle and reduction of area on interlayer pressure using ANSYS 17 for simulation is examined. .By comparing the force-displacement curve in experimental and modeling works, simulation accuracy was good. During the investigation it was found always with reduce reduction of area, percent of the maximum interlayer pressure depend on semi die angle. So that by increases of reduction in area for 5 degrees semi die angle, interlayer pressure does not change. But, for 45 degrees semi die angle the worst effect of reduction in area changes in interlayer pressure is sudden. The pressure changes with increased the semi die angle, depends on the reduction of area. So that the maximum interlayer pressure in 6.2% reduction in area is decreased with increases of semi die angle between 5 to 45 degrees; But, the interlayer pressure in 20% reduction in area, increases with increasing the semi die angle.

---

The purpose of this paper is to experimentally investigate the natural frequencies of notched homogeneous and inhomogeneous specimen made from API X65 steel. The specimens cut from spiral welded pipe, tested on an equipped low blow drop weight tester with accelerometer. The tests were performed according to the API 5L standard. The homogeneous specimen was seamless and included only the base metal, while the inhomogeneous specimen included the weld seam and three zones of base metal, heat affected zone and weld. In the present study the specimens were subjected to hammer low blow in the middle without plastic deformation. The laboratory data (voltage-time) were transferred from time to frequency domain using Fourier transformation and the imposed oscillations were removed from the frequency signal by the Butterworth low pass filter. As the hammer drop height increased, the natural frequency in the specimens was almost constant. The natural frequency in the inhomogeneous specimen was less than the homogeneous specimen. Having information about the natural frequency, it is possible to prevent the destructive phenomenon of resonance in the main test (complete fracture of the specimen). Also, using the results of equipped low blow drop weight test and knowing the natural frequency, the dynamic stress intensity factor of the test specimen can be determined.