镀层厚度对热浸镀锌低碳钢板可成行性的影响

本文评价了热浸镀锌低碳钢板的可成行性，通过采用五种不同镀层重量的镀锌板，分析了镀层厚度对成行性的影响，并且与未采用镀层的镀锌板进行了比较。采用X-射线衍射和计算的织构参数确定镀层的定向结晶，通过采用成形极限图（FLD）对试样进行单轴拉伸试验和对钢板成行性的评价，确定试样的机械性能。根据试验结果可以断定：通过提高镀层厚度，可以减少基面组元的织构参数，这种变化导致镀层薄板屈服强度的提高，但是降低了板材的延展性。对结果进行综合评价，涂层较厚的镀锌钢板成行性好于没有涂层镀锌钢板的成行性，同时也好于其它镀层较厚的钢板成行性。

三边支承一边自由矩形板自由振动分析

板自由振动振形必须具有正交性,采用主振方向排序法建立三边支承一边自由矩形板振形函数表达式可以满足振动微分方程和全部边界条件,又具有振形的正交性.该振形曲线中的振动波形数在主振方向上是唯一的,在另一方向上是不唯一的,振形曲线形状符合板边界条件所能限定的变形形态.通过证明振形正交性的存在,分析振形函数表达式的结构形式,推导不同边界条件矩形板的频率方程,计算板的自振频率及相应振形,并与前人的结果进行了比较,从理论上说明了该方法的正确性.

Unified Solution Method of Rectangular Plate Elastic Bending

The bending of rectangular plate is divided into the generalized statically determinate bending and the generalized statically indeterminate bending based on the analysis of the completeness of calculating condition at the corner point. The former can be solved directly by the equilibrium differential equation and the boundary conditions of four edges of the plate. The latter can be solved by using the superposition principle. Making use of the recommended method, the bending of the plate with all kinds of...

Deflection and stress of hollow CRCP slab under concentrated vehicle load

Based on the equivalence principle of deflection and stress, the concentrated vehicle load which acts on the center of continuously reinforced concrete pavement （CRCP） is translated into the equivalent half-wave sine load by the Fourier transform. On the basis of this transform and the small deflection theory of elastic thin plates, the deflection and stress formulae of CRCP under the concentrated vehicle load with a hollow foundation are put forward. The sensitivity of parameters is analyzed. The results show that maximum deflection is directly proportional to the concentrated vehicle load and the slab width, and inversely proportional to the lateral bending stiffness and slab thickness. The effects of slab width and thickness are significant with regard to maximum deflection. Maximum stress is directly proportional to the concentrated vehicle load and the slab width as well as inversely proportional to slab thickness. The effect of slab thickness is significant with regard to maximum stress. According to the calculation results, the most effective measure to reduce maximum deflection and stress is to increase slab thickness.

Nonlinear principal resonance of magneto-electro-elastic thin plate

Considering magneto-electro-elastic thin plate, the von Karman plate theory of large deflection and the geometric nonlinearity, the mathematical model of nonlinear undamped forced vibration is established. Making use of the improved Lindstedt-Poincare （L-P） method, the undamped forced vibration problem is solved, and the amplitude-frequency response equation of thin plate is obtained. Furthermore, the amplitude frequency response curves of system under different condi- tions are obtained by numerical simulation. The results show that the thickness of the plate, mechanical excitation, parame- ter e, pure piezoelectric material of BaTiO3, pure piezomagnetic material of CoFe2 04, different magneto-electro-elastic ma- terials of BaTiO3/CoFe2 04 and Terfenol-D/PZT will have an impact on the system frequency response. The main effects in- volve principal resonance interval, spring stiffness characteristic and amplitude jumping phenomena.

对扩孔试验用凹模圆角半径的探讨

在航空用金属材料铝合金和钛合金薄板进行成形工艺性能试验研究,发现标准中规定的凹模圆角半径参数并不能满足所有航空金属材料的成形试验要求,在实验分析的基础上指出存在的问题,并通过相应的试验验证提出建议性的修改意见,这对于更好的完善标准的内容,提高材料成形性能试验研究水平和更准确的指导生产具有重要的现实意义。

Bearing mechanism and thickness optimization of ore roof in bauxite stope

Based on the elastic thin plate theory,the main law of the ore roof failure was analyzed and the formula of the ore roof thickness was deduced.The results show that the tensile stress in the roof center accounts for the roof failure.According to the limit failure conditions of the point,the formula of the ore roof thickness was derived.Taking No.10 stope of a bauxite mine as an engineering case,the optimal thickness of the ore roof was 0.36 m.The safety factor was taken as 1.3,therefore the design thickness was 0.5 m.In the whole industrial test process,the dynamic alarm devices did not start the alarm and the ore roof was not damaged.Compared with other stopes under similar conditions,its thickness was reduced by 0.1-0.3 m.The recovery rate of the ore roof was increased by 16.7%-37.5%.

Local Bifurcation of a Thin Rectangle Plate with the Friction Support Boundary

The dynamical equations of a thin rectangle plate subjected to the friction support boundary and its plane force are established in this paper. The local bifurcation of this system is investigated by using L S method and the singularity theory. The Z 2 bifurcation in non degenerate case is discussed. The local bifurcation diagrams of the unfolding parameters and the bifurcation response characters referred to the physical parameters of the system are obtained by numerical simulation. The results of the computer simulation are coincident with the theoretical analysis and experimental results.

Numerical Simulation of Interaction Between Laminar Flow and Elastic Sheet

A numerical simulation of the interaction between laminar flow with low Reynolds number and a highly flexible elastic sheet is presented. The mathematical model for the simulation includes a three-dimensional finitevolume based fluid solver for incompressible viscous flow and a combined finite-discrete element method for the three-dimensional deformation of solid. An immersed boundary method is used to couple the simulation of fluid and solid. It is implemented through a set of immersed boundary points scattered on the solid surface. These points provide a deformable solid wall boundary for the fluid by adding body force to Navier-Stokes equations. The force from the fluid is also obtained for each point and then applied on the boundary nodes of the solid. The vortex-induced vibration of the highly flexible elastic sheet is simulated with the established mathematical model. The simulated results for both swing pattern and oscillation frequency of the elastic sheet in low Reynolds number flow agree well with experimental data.

Mechanics criterion and factors affecting overburden stability in solid dense filling mining

The effect of controlling strata movement in solid filling mining depends on the filling rate of the goal. However, the mechanical property of the overburden in the backfill stope and the designed size of the backfill mining workface should also be considered. In this study, we established a main roof strata model with loads in accordance with the theory of key strata to investigate the stability of the overburden in solid dense filling mining. We analyzed the stress distribution law of the main roof strata based on elastic thin plate theory. The results show that the position of the long side midpoint of the main roof strata failed more easily because of tensile yield, indicating that this position is the area where failure is likely to occur more easily. We also deduced the stability mechanics criterion of the main roof strata based on tensile yield criterion. The factors affecting the stability of the overburden in solid dense filling mining were also analyzed, including the thickness and elasticity modulus of the main roof strata, overlying strata loads, advanced distance and length of workface, and elastic foundation coefficient of backfill body. The research achievements can provide an important theoretical basis for determining the designed size of the solid dense filling mining workface.

Study on stress distribution and failure criterion of the roof for the severely inclined coal seam under long wall working

By turning to the theory of elastic thin plates, a mechanical model of the main roof breaking for severely inclined seam under long wall working was esbalished, in which formulaes were deduced for the calculation of the stress distribution. When the main roof stress distribution was characterized, the failure form of the roof in the long wall coal seam under work was given with the failure criterion deduced. The deduced failure criterion was then applied to the No.3232（3） face of the Li- zuizi Coal Mine; the first pressure for the working face was accurately predicted. Results of the field application show that the main roof of the severely inclined coal seam under long wall working breaks in the O-X pattern, which is basically in accor- dance with the reality.

Influence of variables in deep drawing of AA 6061 sheet

Deep drawing is one of the most important processes for forming sheet metal parts.It is widely used for mass production of cup shapes in automobile,aerospace and packaging industries.Cup drawing,besides its importance as forming process,also serves as a basic test for the sheet metal formability.The effect of equipment and tooling parameters results in complex deformation mechanism.Existence of thickness variation in the formed part may cause stress concentration and may lead to acceleration of damage.Using TAGUCHI's signal-to-noise ratio,it is determined that the die shoulder radius has major influence followed by blank holder force and punch nose radius on the thickness distribution of the deep drawn cup of AA 6061 sheet.The optimum levels of the above three factors,for the most even wall thickness distribution,are found to be punch nose radius of 3 mm,die shoulder radius of 8 mm and blank holder force of 4 kN.

Elastic-plastic properties of thin film on elastic-plastic substrates characterized by nanoindentation test

To characterize the elastic-plastic properties of thin film materials on elastic-plastic substrates,a simple theory model was proposed,which included three steps:dimensionless analysis,finite element modeling and data fitting.The dimensionless analysis was applied to deriving two preliminary nondimensional relationships of the material properties,and finite element modeling and data fitting were carried out to establish their explicit forms.Numerical indentation tests were carried out to examine the effectiveness of the proposed model and the good agreement shows that the proposed theory model can be applied in practice.

Mathematical Model of Dynamics of Micropolar Orthotropic Elastic Thin Bars with Free Fields of Displacements and Rotations

In the present paper, initial-boundary value problem of plane stress state of micropolar theory of elasticity is considered for orthotropic material in the domain of thin rectangle. General hypotheses are formulated, which are the qualitative results of the asymptotic method of integration of the stated initial-boundary value problem. On the basis of the accepted hypotheses general applied one-dimensional models of dynamics of bending deformation of micropolar orthotropic elastic thin bars with free fields of displacements and rotations are constructed with and without consideration of shear deformations. With the help of the constructed models different dynamic problems of micropolar bars can be studied. Here concrete problems of free and forced vibrations of hinged supported micropolar orthotropic elastic thin bar are studied. Numerical analysis is done and specific features of dynamic characteristics of micropolar material are revealed. Particularly, it is shown that there is a frequency of vibrations of the micropolar bar that does not depend on bar sizes.

Stochastic Bifurcation of Rectangular Thin Plate Vibration System Subjected to Axial Inplane Gaussian White Noise Excitation

A stochastic nonlinear dynamical model is proposed to describe the vibration of rectangular thin plate under axial inplane excitation considering the influence of random environment factors. Firstly, the model is simplified by applying the stochastic averaging method of quasi-nonintegrable Hamilton system. Secondly, the methods of Lyapunov exponent and boundary classification associated with diffusion process are utilized to analyze the stochastic stability of the trivial solution of the system. Thirdly, the stochastic Hopf bifurcation of the vibration model is explored according to the qualitative changes in stationary probability density of system response, showing that the stochastic Hopf bifurcation occurs at two critical parametric values. Finally, some explanations are given in a simple way on the potential applications of stochastic stability and bifurcation analysis.

Some Aspects of the Behavior for Orthotropic Thin Plates with Clamped Edges

In most structural applications, composite structures can be idealized as beams, plates or shells. The analysis is reduced from three-dimensional elasticity problem to a one-dimensional, or two-dimensional problem, based on certain simplifying assumptions that can be made because the structure is thin. In this article is presented the mathematical model properly thin orthotropic plates, based on simplifying assumptions Love- Kirchhoff and small deformations. Proposed analytical solutions are considered both for solving equation orthotropic rectangular plates and for modal analysis, in the case of plates with clamped edges. The purposed solutions were analysed considering a FEM solution for comparison and the experimental test results.

Effect of large strain cross rolling on microstructure and properties of Al-Li alloy plates with high magnesium content

Transmission electron microscopy(TEM),electron backscattered diffraction imaging(EBSD)and X-ray diffractometry were used to analyze the microstructure and texture characteristics of Al-9.8Mg-1.5Li-0.4Mn alloy cross-rolled and extruded plates,and the tensile properties and deep drawing performance were measured.The results show that the occurrence of dynamic recrystallization was promoted,the grains were refined and the preferred orientation of the recrystallized grains was improved by large strain cross rolling.Compared with CBA and CCB rolling methods,CBB rolling method significantly reduced the orientation density of the typical Brass texture{110}?112?in the extruded plates.The orientation densities of Copper texture{112}?111?and Brass texture{110}?112?on theβorientation line in the CBB rolled plates were the lowest,and there were no typical texture features in the plates.Meanwhile,better deep drawing could be gained in the CBB rolled plates,and the mechanical properties of the 0°,45°and 90°directions were basically the same.The tensile strength,yield strength and elongation at room temperature for the CBB rolled plates were 617 MPa,523 MPa and over 20.1%,respectively.The deviation of the mechanical properties at different directions was less than 3%.

Geometrical, microstructural and mechanical characterization of pulse laser welded thin sheet 5052-H32 aluminium alloy for aerospace applications

Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aerospace industry.The microstructure and mechanical properties of the weldments were also investigated.Relationships between the parameters and weld bead geometry were found.High quality weld joints without solidification crack that met AWS D17.1 requirements were obtained at(I)high pulse energy(25 J)and high average peak power(4.2 kW)and(II)low pulse energy(17.6 J)and low average peak power(2.8 kW).The weld joint formed at lower heat energy input exhibited finer dendritic grain structure.Mg vapourisation and hard phase compound(Al0.5Fe3Si0.5)formation decreased in the weld joint formed at lower heat energy input.Consequently,the tensile strength of the weldment formed at lower heat energy input(168 MPa)is by a factor of 1.15 higher but showed^29%decrease in hardness(111 HV0.1)at the joint when being compared with the weldment formed at higher heat energy input.Appropriate parameters selection is critical to obtaining 0.6 mm-thick AA5052-H32 pulse laser weld joints that meet AWS D17.1 requirements for aircraft structures.

Experiment research on mechanical behavior of the aluminum laminate in the low-high temperature

Aluminum laminate is one kind of the rigidizable composite materials and plays an important role in construction of the inflatable space structure(ISS),which has potential application in space in the future.But the study of the predecessors mainly focuses on the research of the mechanical behavior in the room temperature,for this reason,mechanical properties of the aluminum laminate in low-high temperature have been studied in this paper.The failure mechanism of the aluminum laminate is also analyzed in the microscopic view by JCXA-T33 electron probe.The results show uhat the temperature has significant influence on the strength and Young's modulus of the aluminum laminate.With the increase of temperature,both the strength and Young's modulus of the aluminum laminate decrease.A model between Young's modulus of the aluminum laminate and temperatures is obtained by using Arrhenius equation.The predicted values by the model agree well with the experiment values.

Microstructure and Magnetic Properties of Sputtered Co5Sm Films

Co5 Sm/Cr bilayer films were deposited on Si and glass slides by means of a Direct-Current （DC） magnetron sputtering system with substrate heating. Magnetic properties measurements show that the sample with glass substrate has a comparatively large coercivity （He = 2 141.20e） with a rela- tively low optimal temperature （ Ts =350 ℃ ）. X-ray diffraction patterns indicate that Cr presents a hexagonal-close-packed （hcp） texture on Si, while a body-centered-cubic （bcc） struc- ture on glass substrate, which leads to Cos Sm films having dif- ferent lattice constants on Si and glass substrates. At their opti- mal temperature, the grain size of the sample on glass slide is smaller with its size distribution more uniform. Concurrently, the shape of magnetic domain is more regular and ordered. The value of magnetic switching volume （ V ） for the film on glass is 1.65×10-18 cm3 , smaller than that for films on Si. For the film on glass, the magnetization reversal mechanism is mainly influenced by magnetocrystalline anisotropy, the shape of the crystal grain and the stress in the film.