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When higher strain rate of 10 sec -1 was used, the area fraction of dynamically recrystallized grains increased substantially, but the average grain size was not affected.
Introduction As a nickel-based superalloy, alloy 718 is extensively used in the fabrication of critical components for turbine engines due to its excellent mechanical properties at elevated temperatures and good corrosion resistance.
Since mechanical properties of alloy 718 significantly depends on the grain size, prediction of grain size and its distribution of the hot deformed and/or reheated alloy 718 is very important [2,3].
Dynamic and static recrystallization was identified as major controlling factors for microstructure when the hot compression test and reheating were conducted. 2.

Financial factors, as well as the ease of machining ferritic steel, justify this manufacturing option.
Experimental Results The typical cross section microstructure of the weld cladding samples is shown in Fig. 2, where three clad layers, heat affected zone (HAZ) and unaffected zone of the substrate are distinguishable.
The clad (three layers together) has an average thickness of 9.4±0.5 mm and the thickness of the heat affected zone (HAZ) is 2.2±0.4 mm.
These residual stresses should correspond to the milling affected zone created by the mechanical processes applied in the sample surface.
This increase in compressive stresses with heat treatment temperature is related to the differences in the physical properties of carbon and stainless steels.

Research and comparison of blade natural frequencies is made in different rotational working conditions taking into account external factors such as the rotational inertia force.
At present, most of large blades are made of composite materials of fiber reinforced plastic (FRP), FRP has the merit of high specific strength, good fatigue properties and well damping properties.
The mechanical properties of glass fiber reinforced plastic materials as shown in Tab.1: Tab.1 Material Character of FRP Material Ex Ey Gxy Poisson Density 7:1 FRP [Pa] [Pa] [Pa] 0.22 1950[kg/m3] 1:1 FRP [Pa] [Pa] [Pa] 0.14 1950[kg/m3] 2 Modal frequency analysis of the blade 2.1 Additional stiffness The inertial centrifugal force caused by the blade rotary motion, wind load and other loads of the coupling action increases when the wind turbine rotating, it’s increasing the blade stiffness as well appearing stiffening effect.
At the same time, the different thickness of layers from the tail to the tip and the change for sections of blade web also cause blade stiffness and quality distributed unevenly , therefore, changing for layers in cross section characteristic and the structure performance will affect modal vibration mode of blade and the changes for all order natural frequency.
The results showed that the blade in operation won't resonate to damage, stress stiffening of large wind turbine blade in operation effects on the modal frequency significantly, which cannot be oversight in practical application; and the layer angles of the blade of wind turbine can change the stiffness of blade, and affect the modal frequency, which means modal frequency of the blade can be devised.

In the process of 3D printing, the alloy undergoes significant phase transformations, which have an important effect on the mechanical properties of the final products [4], and naturally affects, among other things, the machinability.
Moreover the latter, as a rule, is the fundamental determining factor in the analysis of mechanical characteristics.
Changing the properties of the material could not but affect the characteristics of its machinability, and the features of milling titanium alloy obtained by the electron beam melting method revealed.
[3] M.Simonelli, Y.Y.Tse,C.Tuck, Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti-6Al-4V, Materials Science & Engineering A 616 (2014) 1-11
[4] A.Popovich, V.Sufliarov, E.Borisov, I.Polozov, Microstructure and Mechanical Properties of Ti-6AL-4V Manufactured by SLM, Key Engineering Materials 651-653 (2015) 677-682

Table 1 Physical and mechanical properties of cement Density /(kg·m-3) Setting time/min Compressive Strength/MPa Flexural Strength/MPa Initial setting time Final setting time 3d 28d 3d 28d 3.10 123 215 28.5 55.3 5.6 8.9 Table 2 Physical properties of polypropylene fibers Density/(g·cm-3) Melting point/ Tensile strength h/MPa Elastic modulus/MPa Elongation/% 0.91 165 540 5588 23 Experimental Design.C25 pumping concrete of ultra-fine sand is prepared with water-to-cement ratio (w/c) of 0.4 and sand ratio of 27%.In this paper, initial cracking duration, maximum crack width and total crack area of concrete are tested by slab test to evaluate concrete plastic shrinkage cracking.
Choose fly ash, admixture(pumping agent, water reducing agent, air-entraining agent), polypropylene fiber and so on from the common concrete materials as testing factors to study the influence law of the performance of raw materials on plastic shrinkage of pumping concrete of ultra-fine sand.
Select the water reducing agent, the pumping agent and the air entraining as experiment factor from commonly used admixture of pumping concrete.
These are much better than affect that water reducing agent single mixed.
Fibers play the role of bridge, which increased the tensile strength of materials to resist plastic cracking depending on the adsorption bond strength between fibers and concrete, and finally decreased cracking extent by reducing fracture speed and crack width depending on its mechanical properties.

The agricultural development of mountainous hilly country is seriously affected.
As the soil has a multi-phase, loose dispersion characteristics and properties, using a continuous physical theory and its numerical solution (finite element method or boundary element method) is difficult to describe the anti-rotation grubbing harden soil process [6].
Orthogonal Design of Chisel-Cutting Parts Factors Level 1 2 3 structure soil cutting angle(o) A 60 65 70 the effective clearance angle (o) B 3 6 10 Blade shape C I II III Orthogonal Experiments of Structural Parameters of Cutting Part.
Based on preliminary analysis, listing the tip structure of factors and levels, see Table II.
Orthogonal array to study the impact factors of each level, pairs of orthogonal experimental results corresponding to the processing and analysis, specifically in table V.

Abstract: Tensile properties and fracture morphologies of C/C composites used as aircraft brake disc at different heat treatment temperature have been studied.
In the course of manufacturing C/C composites brake disc, heat treatment is a very important working procedure, which affects the property of C/C composite material directly[3-5].
Tensile mechanical property test was conducted for C/C composites after heat treatment at different temperature, and fracture morphologies of tensile sample were observed with SEM. 2.
Under the protection of argon gas, five samples marked as A, B, C, D, E, were heat treated at 2000�, 2300�, 2400�, 2500� and 2650� for 2h respectively. 2.2 Mechanical property testing Tensile test was performed with an MTS880-50KN universal testing machine (US) Loading velocity was kept at 1mm/min, and the environment temperature and humidity were 20�and 50% respectively.
e2 e3 e1 a3 a2 c2 a1 c1 c3 With increase of heat treatment temperature continuously, mechanical property of carbon fiber continues to decline and microstructure of C/C composites will change largely.

The nature of these properties has been intensively studied by both experimental and theoretical approaches.
For structural materials, the thermal expansion often crucially affects mechanical strength.
These extraordinary mechanical properties are caused by the formation of tiny LPSO precipitate phases in α-Mg matrix.
The refined cell parameters and reliable factors (Rwp) are summarized in Table 1.
We believe these informations are usefull to reveal the mechanism for extraordinary mechanical properties of LPSO Mg alloys.

The loads on the arch dam and the materials physical properties of the dam and the bedrock are uncertain, and can be described with random variable.
As we all know, the arch dam is a higher order statically indeterminate structure, the temperature variation affect the dam stress greatly [11-12].
The statistical properties of the random variables are shown in Table 1.
Based on the calculation and analysis, the safety factor of the load combination of the dam is controlled by: weight, water pressure and temperature load rise.
(3) Clearly the temperature change random field affects the reliability of the arch dam in the reliability analysis.

Weld 1ines will affect the surface quality of the products, even cause plastic scrap.
So the weld lines that the first project didn’t affect the quality of the helmet and mechanical properties [5].The warp analysis mainly is used to judge if the deformation appears in the injection molding of the thermoplastic material.
The value of warp was 1.718mm.The value of warp was 1.186mm due to the cooling factor.
The value of warp was 0.8068 due to the contract factor.
Beijing: mechanical industry press, 2003