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Introduction With the rapid development in the field of radio astronomy in China,the better electrical properties of the antenna is under construction.
During parameters of large diameter antenna’s electrical performance,gain reduction factor(efficiency) and gain are important and they have close relationship with sensitivity and resolution[1].So as high reliability and precision antenna must ensure that such parameters are always in the optimal state.Large-diameter antenna’s efficiency and gain always be reduced by a variety of factors,where the deformation of the antenna structure is a more direct factor.
Antenna parameters about electrical properties 1) Efficiency The efficiency of large-diameter reflector antenna is an important parameter to measure the electrical performance of the antenna,and it can be shown like this: (1) Where Aeff,0 is the maximum effective area of the antenna,Ag represents the geometric area of the antenna.Gravity deformation which is caused by elevation change will reduce accuracy of antenna’s main panel and then affect the electrical properties of antenna[5].The geometric area of antenna can not be changed,so if efficiency reduces,maximum effective area of main panel will reduce.
Through the analysis of model geometry and stress state,combining with unit libraries and their properties of ANSYS,after simplification the surface of the central body will be composed of different shapes,which can be replaced by shell unit Shell63,brace of antenna and bracket of feed can be replaced by beam unit Beam4.Materials of units are all replaced by steel.
After finishing building model,type of unit, the correspondence between the name and number of the antenna 25 m are shown in Table 1.Material and properties is shown in Table 2.

Then, the samples were subjected to quasi-static tensile tests at elevated temperatures, including 25°C (RT), 75, 100, 125, 150 and 175°C, to measure their mechanical properties.
Introduction Recently, APC-2 composites have been selected as one of the best candidates for advanced and high performance aerospace engineering and structural applications, because of their superior mechanical properties, high resistance to severe environmental condition and delamination, good damage tolerance, and high impact toughness, especially at high temperature, [1].
Also, the elevation of service temperature can deteriorate the material properties.
(ed.), Mechanical Properties and Morphology of Poly (Etheretherketone), Toughened Composites, ASTM STP 937 (1987), American Society for Testing and Materials, Philadelphia, pp.342-357
Chen, "Mechanical Properties in Notched AS-4/PEEK APC-2 Composite Laminates at Elevated Temperature", Journal of Composite Materials, Vol. 40 (2006), No. 11, pp.955-969

Strength, evenness, hairiness and other properties of the low twist yarns were also investigated.
Fiber composition, cross-sectional shape, size, buckling extent, and spatial distribution are important factors to affect the yarn luster [5].
Due to reversed twist, cotton fiber in the roving yarn gets rid of the shackles of twist, retains the original bending and excellent convolution properties.
[4] Y.L.Ge,Y.H.Cui:Correlation study of the structure and properties of bamboo fiber yarn, Shanghai Textile Science & Technology.Vol.11(2009),p.23. ( In Chinese)
[5]Y.Jiang: Structure and properties of the yarn which made with differential shrinkage yarn the air deformation (multiple deformation) Donghua University doctoral thesis.Vol. (2009), p.102.

Mechanical Properties Microhardness.
Tensile Properties.
Yet, repair welding can lead to changes in mechanical properties of welded structure.
Contreras, Effect of multiple repairs in girth welds of pipelines on the mechanical properties.
Chennaiah, Effect of Heat Input on the Mechanical Properties od GMAW Welded Dissimilar Joints.

Biegler [17] proposed an automated toolpath generation for arbitrary geometries based on metal additive manufacturing properties.
Sun [20] studies the influence of two 316L powder compositions in the repair of parts, focusing on analysing the repaired area's microstructure and its mechanical properties.
This work shows the influence of the angle of the pre-machined trapezoidal grooves in the reconstruction process, analysing the density, microstructure, and mechanical properties of the repaired part.
Mazzucato [23] demonstrates that deposition strategies and laser power directly influence the melt pool's shape and the reconstructed part's mechanical properties.
Sun et al., “Laser metal deposition as repair technology for 316L stainless steel: Influence of feeding powder compositions on microstructure and mechanical properties,” Opt Laser Technol, vol. 109, pp. 71–83, 2019, doi: 10.1016/j.optlastec.2018.07.051

The mechanical properties of magnesium alloys under dynamic loading have not been explored in sufficient depth.
However, magnesium alloys are not generally used for structural elements in automobiles because their ductility and/or toughness are low at room temperature [1-3] and their mechanical properties under impact loading have not investigated in sufficient depth.
The material properties of the specimen are shown in Table 1, and the yield stress and plastic strain at failure used for input data are listed in Table 2.
Table 1 Material properties of AZ31 magnesium alloy and 7075 aluminum alloy.
V is the battery voltage, K is the gauge factor, E is the Young’s modulus of the transmission bars, respctively.

The broken analysis of 220kV transmission line tension crimp barrel steel core Guodong Han1,3, a, Shuting Wan1,b, Zhangqin Wu2, c, Zhanjie Lv1,3,d , Ronghai Liu2, e, Jin Wang2, f 1 Department of Mechanical Engineering, North China Electric Power University, China,Baoding 071003,2 Electric Power Research Institute, Yunnan Electric Power Test & Research Institute Group Co.Ltd., China,Kunming 650217, 3 Graduate Workstation of North China Electric Power University & Yunnan Electric Power Grid Corporation ahgd100629@126.com, bwanshuting1@sina.com, c 1031172082@qq.com, d 1043398404@qq.com, e 23697835@qq.com, f25335572@qq.com Keywords: 220kV transmission line, Tension crimp barrel, Steel core broken, Cause Analysis Abstract.
Crimp quality directly affects the mechanical properties and electrical conductivity of the wire.
The above factors have contributed to tensile strength of two tension crimp barrels decreased.
In practice engineering, wire crimping quality is the key factor that affecting the performance of the wire, Improved crimping measures and standardized crimping method can effectively protect the wire crimp quality.

It showed the densification is the most important factor which affects the thermal conductivity of the composites and the obtained highest thermal conductivity is 182W/m.K.
Another obvious disadvantage of CVI coating are the introduction of the expensive and time-consuming process will not only improve the production cost, but also induce more uncertain factors to vary the properties of the composites.
Mechanical properties with bend strength of 306MPa and Young's modulus of 280GPa for were also measured in this study.
Although the thermophysiacal properties of diamond/Al composite have been reported frequently, little information is available about their mechanical behavior.
High mechanical properties were also shown in this work with bend strength of 306MPa and Young's modulus of 286GPa.

Based on mechanical properties of railway extradosed cable-stayed bridge with the rigid continuous beam system in the high-intensity earthquake zone, three kinds of scheme on seismic response reduction including viscous dampers, lock-up device and friction sliding bearings is presented in the text and effectiveness of seismic response reduction is analyzed by using non-linear time history response analysis .
Literatures (Zhang,2009) studied the isolation properties of viscous dampers on the continuous beam bridge and cable-stayed bridge; Literatures (Wang,2006) studied the isolation effect of Lock-up device on the of Continuous beam bridges; Literature (Fang,2003) studied the isolation properties of friction sliding bearings on the continuous beam bridge.
Mechanical model of Seismic Isolation Devices Mechanical model of viscous liquid damper The composition of nonlinear viscous dampers consists of piston, fuel tank and orifice.
Mechanical model o f Friction Sliding Bearings The mechanical model of friction sliding bearings can be simulate by using friction elements.
In order to avoid the damage of dampers prior to damage of structure, after a comprehensive consideration of the structural damping effect and the facilitated local connection design, its reasonable mechanical parameters should be: damping coefficient C=20,000, speed index factor = 0.3.

Good agreement of stress intensity factor along crack length was obtained between numerical and experimental results.
There are some parameters that can affect SD fatigue life: SD diameter, position and surface finish of the SD, crack length, geometry and mechanical properties of the component, load history, type and magnitude, and residual stresses around the SD.
Several authors have been studying SD technique in an attempt to understand how certain parameters can affect stop-drill fatigue life.
Acording to Branco [10], stress intensity factor range (∆K) can be calculated using expression ∆K = Y ∆σ√πa, were a is the crack length, b is the specimen width and Y is the geometric factor.
• Computational results showed a small number of cycles supported by SD due to its strong dependence on Morrow relation parameters and aluminium mechanical properties, which were obtained from literature.Figura 1: Specimen geometry.