A constitutive model based on energy density for power-law variable thickness plates and its application.

Variable thickness plates are relatively common structure in large-scale transportation equipment such as aerospace and ships. Due to their high running speed and large structural dimensions, such structures are usually induced high-frequency severe vibrations, which likely lead to structural damage. Therefore, it is crucial to accurately predict the high-frequency dynamic response characteristics during the structural design phase.

Multiscale characterization and contact performance analysis of machining surfaces.

Accurately characterizing the surface topography of parts is crucial to improve the surface measurement accuracy and analyze the surface contact performance. A method is proposed to separate the morphological characteristics of the actual machined surface based on the layer-by-layer error reconstruction method and the signal-to-noise ratio method during the wavelet transform process, so as to evaluate the contact performance of the different joint surfaces. First, the actual machined surface morphological features are separated by using the wavelet transform method, the layer-by-layer error reconstruction method, and the signal-to-noise ratio method.

Q-Factor Enhancement of Coupling Bragg and Local Resonance Band Gaps in Single-Phase Phononic Crystals for TPOS MEMS Resonator.

This paper presents a type of single-phase double "I" hole phononic crystal (DIH-PnC) structure, which is formed by vertically intersecting double "I" holes. By using the finite element method, the complex energy band curve, special point mode shapes, and different delay lines were calculated. Numerical results showed that DIH-PnC yielded ultra-wide band gaps with strong attenuation.

Rotary Friction Welding of Molybdenum without Upset Forging.

A large instantaneous axial forging load is required to be applied for the final stage of rotary friction welding (RFW), which is usually conducive to obtaining clean, compact, and high-quality joints. However, for slender fuel claddings made of molybdenum (Mo) with low stiffness, the instantaneous axial forging load cannot be applied at the final stage of welding. This study carried out RFW tests without upset forging on Mo in the atmospheric environment and investigated the effects of welding time on joint morphology, axial shortening, microstructures, microhardness, tensile strength, and tensile fracture morphology.

Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy.

Porosity defects are still a challenging issue in the fusion welding of molybdenum and its alloys due to the pre-existing interior defects associated with the powder metallurgy process. Fiber laser welding of end plug and cladding tube made of nanostructured high-strength molybdenum (NS-Mo) alloy was performed in this work with an emphasis on the role of welding heat input. The distribution and morphology of porosity defects in the welded joints were examined by computed tomography (CT) and scanning electron microscopy (SEM).

Effects of Laser Welding and Post-Weld Heat Treatment on Microstructure and Mechanical Properties of Aged Ti55531 Alloy.

As one of the relatively new titanium (Ti) alloys in the engineering field, β-Ti alloy⁻Ti55531 has attracted a great deal of attention due to its excellent mechanical properties, while a few research papers on weldability and the post-weld heat treatment (PWHT) process of Ti55531 have been reported. Based on an orthogonal experiment design, the parameters of laser beam welding (LBW) of Ti55531 alloy with a thickness of 2 mm were optimized. Moreover, the influences of welding parameters and PWHT on the microstructures and performance of the laser-welded joint of Ti55531 were analyzed.

Multipurpose piezoelectrical ceramic materials and high performance transducers are used for the ultrasonic medicine.

This paper briefly reports on preparations and applications of two kind multipurpose medical piezoelectrical ultrasonic transducer materials, high-performance medical ultrasonic diagnosis transducers and medical ultrasonic therapy transducers in present work, then, some problems of the piezoelectric materials and devices used for the ultrasonic medicine which need further researches are pointed out.