Thermo-Mechanical Problem of Torque in Beam with Annular Cross-Section

2010 ◽  
Vol 638-642 ◽  
pp. 2007-2012
Author(s):  
Joze Stropnik ◽  
Franc Kosel

The paper deals with the problem of the torque in the cantilever beam with annular cross section in the elasto-plastic domain, considering the material with elastic-linear hardening model. The cantilever beam is subjected to the alternating load of such frequency that the heat is generated in the beam. The quantity of the generated heat depends on the amplitude of the torque, frequency of the load and mechanical properties of the beam material. Equations which relate the value of the torque to the extent of the plastic region of the cross section and the shearing stresses of the beam in the elasto-plastic domain are given. Furthermore, equations for deformation work, transformation work, energy due to residual stresses and energy transformed into heat are presented. The article compares results concerning the temperature change at characteristic points along the beam, obtained via numerical analysis as well as experimentally.

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 772
Author(s):  
Xianming He ◽  
Dongxiao Li ◽  
Hong Zhou ◽  
Xindan Hui ◽  
Xiaojing Mu

The piezoelectric vibration energy harvester (PVEH) based on the variable cross-section cantilever beam (VCSCB) structure has the advantages of uniform axial strain distribution and high output power density, so it has become a research hotspot of the PVEH. However, its electromechanical model needs to be further studied. In this paper, the bidirectional coupled distributed parameter electromechanical model of the MEMS VCSCB based PVEH is constructed, analytically solved, and verified, which laid an important theoretical foundation for structural design and optimization, performance improvement, and output prediction of the PVEH. Based on the constructed model, the output performances of five kinds of VCSCB based PVEHs with different cross-sectional shapes were compared and analyzed. The results show that the PVEH with the concave quadratic beam shape has the best output due to the uniform surface stress distribution. Additionally, the influence of the main structural parameters of the MEMS trapezoidal cantilever beam (TCB) based PVEH on the output performance of the device is theoretically analyzed. Finally, a prototype of the Aluminum Nitride (AlN) TCB based PVEH is designed and developed. The peak open-circuit voltage and normalized power density of the device can reach 5.64 V and 742 μW/cm3/g2, which is in good agreement with the theoretical model value. The prototype has wide application prospects in the power supply of the wireless sensor network node such as the structural health monitoring system and the Internet of Things.


Author(s):  
J. W. Xing ◽  
G. T. Zheng

As highly sensitive to structural parameter variations, it is necessary to study relations between derivatives of displacement modes and structural design parameters. This paper proposes an integral technique for obtaining the analytical solutions of slope and curvature modes of arbitrary cross-section inhomogeneous cantilever beam. The method is validated by comparing the computation results of modal frequencies and shapes with both numerical and analytical solutions. Furthermore, based on the presented method, we have established explicit expressions for the structural parameters sensitivity of the slope/curvature mode shapes. An example of parameter design is also presented for a cantilever beam with the proposed sensitivity analysis method.


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