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Introduction The main failure modes of metal materials are fatigue, corrosion and wear which all start at material surface.Therefore, the structure and properties of the metal material directly affect its comprehensive properties.
Multiple surface strengthening technologies have been applied to improve the surface properties, including shot peening, rolling and inside extrusion, etc.
However, the crack growing speed could generally be reduced greatly, and the range value of factor threshold of stress intensity could be raised distinctly in some strengthened regions.
Experiments 7050 alloy sheet was made into Single-Edged Notched Tensile (SENT) samples, The common mechanical properties of the material are shown in table 1.
Chemic component and mechanical properties of the 7050 Composition percent [%] Trademark Si Fe Cu Mn Mg Cr Zr Zn Ti Al 7050 ≤0.12 ≤0.15 2.0～ 2.6 ≤0.10 1.9～ 2.6 ≤0.04 0.08～ 0.15 5.7～ 6.7 ≤0.06 rest Yield strength σb（Mpa） Tensile strength σ0.2（Mpa） δs （%） Ψ（%） 434 503 9 6 MTS880 material testing system was adopted for fatigue experiment in which tensile stress fatigue was adopted with load control.

As a flexible adjustment layer slab track is the slab track important core component of its performance directly affects the durability and maintenance workload slab track use , it determines the success or failure of the plate BALLASTLESS track the success of technology .
This test is mainly to discuss the impact of aluminum on the mountains of sand as aggregate of CA mortar properties.
Mechanisms mountain sand rocks in specially made mechanical crushing, its basic physical properties are shown in Table 1.
The reason is that aluminum powder mixed with excessive lead content in excess of CA mortar internal voids , as well as the cement can not provide more strength, a variety of factors in the external environment, the strength but somewhat reduced.

Previous experimental researches and observations indicated[2]that bond degradation is one of the important factors which have affect on the structure dynamic response.
The mechanical bite force between concrete and reinforcment rib disappeard at load end and was replaced by the follow ribs gradually.
Bond properties between reinforcement and self - compacting concrete[J].
An Experimental Study of Bond-Anchorage Properties of Bars in concrete.

Prestressed structure has many advantages, such as: improve the structure performance; reduce component section height, reduce weight, make full use of high strength reinforcement; has a good crack closure properties and deformation recovery performance; improve the shear bearing capacity, and improve the fatigue strength, etc.
But on the other hand, there are many barriers of prestressed development factors, among which the most outstanding one reason is high cost of prestressed dosage.
To a certain extent, it has seriously affected the popularity of prestressed technology promotion.
Pang Ping, Mechanical properties research of unbonded prestressed concrete continuous slab, a master's degree thesis, 2001.6

The recycled aggregate concrete must, however, satisfy certain mechanical and durability requirements before it can be used as a structural material.
Perhaps, the most important of these factors is the ability of concrete to resist flow of fluids through it: a property that is referred to as permeability.
The resistance to chloride-ion penetration into concrete is a crucial paramete affecting the durability of concrete structures exposed to marine environment [2].
So far a number of studies have been performed by using recycled aggregate in concrete attempting to understand the properties of RAC; Among them, most of the studies are mainly focused on the mechanical properties of the resulting concrete, limited work is carried out on the understanding of the durability aspects of the emerging construction material as is probably with concrete that is made with natural aggregate [3].
Xu: Expwrimental Study on Influence of Recycled Coarse Aggregates Contents on Properties of Recycled Aggregate Concrete.

A list of some of their properties is presented in Table 1.
As can be seen from Table 1, there are small differences between the two grades and their mechanical properties.
Specific material properties of GUR 1020 and 1050.
Sterilize the components in a manner typical of that in clinical use for such devices, including total dose and dose rate, as these may affect the wear properties of the materials.
As secondary factors that contributed to increased wear rate include positioning errors.

The buckling and surface friction properties of hairiness fiber are the basic factors for tactile perception [1].The shape and mechanical properties of hairiness fibers on surface directly affect the contact force[2], however, the brain function of tactile perception for the soft fibrous surface is unclear, especially with local skin temperature changing.

Determination of Growing Direction of Fatigue Crack Yao DAI1, a , Wei TAN 2, b, Chang-qing SUN 1 and Jia-wen HE3, c 1 Department of Mechanical Engineering, Armored Force Engineering College, Beijing 100072, China 2 Department of Materials and Engineering, Armored Force Engineering College 3 Department of Materials and Engineering, Xi'an Jiaotong University, Xi'an 710049, China a yao_dai@yahoo.com.cn , btw050400@vip.sina.com, c jwhe@xjtu.edu.cn Keywords: Interfacial crack; Non-homogeneous material; Crack growing direction; Wedge-shape model; Method of arbitrary lines.
It is well known that it is unreasonable to take the interface as a traditional ideally geometrical interface with discontinuity or jump of material properties.
FEM, BEM, MAL, are usually adopted to determine the stress intensity factors or the tip fields of the interfacial cracks.
It is very difficult to determine the crack growing directions accurately due to the limitation of the element properties.
The rectangular domain consists of base material (BM), heat-affected zone (HAZ) and welding material (WM).

Thus, outstanding chemical and physical material properties can be adjusted.
The synthesis of new ceramic materials and the development of novel fabrication techniques are expected to be the key factors for further optimization of properties, especially at high temperatures.
Micropyretically synthesized products have also been reported to have better mechanical and physical properties [16,17].
Metal borides are a group of ceramic materials with outstanding and attractive properties for technological applications.
These larger variations formed at the ignition spot may enlarge heterogeneity in microstructure and properties.

Study on CTOD Fracture Toughness of Welded Joint of X80 Marine Drilling Riser Peng Wang1, a, Meijuan Hu1,b and En Dang2,c 1Key Laboratory for Mechanical & Environment Behavior of Tubular Goods, CNPC Tubular Goods Research Institute, Xi’an, Shaanxi, 710065, China 2Bao Ji Oilfield Machinery Co.
The three point bending specimens are made in the weld center line and heat affected zone for the butt-welded joint in Φ533×25.4mm X80 marine drilling riser respectively according to the requirement of the standard.
Thus, it is very necessary for marine drilling riser to evaluate the fracture toughness property of the welded joint.
CTOD (crack tip opening displacement) is an important parameter to assess the property of anti brittle failure for base metal and welded joint, which could be used to evaluate the safe reliability of structure [3].
Testing Method According to BS 7448 Standard, three point bending experiment is performed at 0℃, in which the displacement is controlled monotonic loading at a constant rate of increase in stress intensity factor within the range 0.5 to 3.0 during the initial elastic deformation.