ON THE ORIENTATION OF BUCKLING DIRECTION OF ANISOTROPIC ELASTIC PLATE UNDER UNIAXIAL COMPRESSION

The theory of small deformation superimposed on a largedeformation of an elastic solid is used to investigate the bucklingof anisotropic elastic plate under uniaxial compression. The bucklingdirec- tion (th direction of buckling direction is obtained. It isfound that the out-of-plane buckling of anisotropic elastic plate ispossible and both buckling conditions for flexural and extensionalmodes are presented.

Three-dimensional free vibration analysis of multi-directional functionally graded piezoelectric annular plates on elastic foundations via state space based differential quadrature method

The three-dimensional free vibration analysis of a multi-directional func- tionally graded piezoelectric （FGP） annular plate resting on two parameter （Pasternak） elastic foundations is investigated under different boundary conditions. The material properties are assumed to vary continuously along the radial and thickness directions and have exponent-law distribution. A semi-analytical approach named the state space based differential quadrature method （SSDQM） is used to provide an analytical solution along the thickness using the state space method （SSM） and an approximate solution along the radial direction using the one-dimensional differential quadrature method （DQM）. The influence of the Winkler and shear stiffness of the foundation~ the material property graded variations, and the circumferential wave number on the nomdimensional natural frequency of multi-directional FGP annular plates is studied.

AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES

Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical nu- merical method is with great advantage in the computational efficiency. Moreover, study on ax- isymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials.

Thermal Effect on Vibration of Parallelogram Plate of Bi-Direction Linearly Varying Thickness

In this paper, the effect of thermal gradient on the vibration of parallelogram plate with linearly varying thickness in both direction having clamped boundary conditions on all the four edges is analyzed. Thermal effect on vibration of such plate has been taken as one-dimensional distribution in linear form only. An approximate but quiet convenient frequency equation is derived using Rayleigh-Ritz technique with a two-term deflection function. The frequencies corresponding to the first two modes of vibration of a clamped parallelogram plate have been computed for different values of aspect ratio, thermal gradient, taper constants and skew angle. The results have been presented in tabular forms. The results obtained in this study are reduced to that of unheated parallelogram plates of uniform thickness and have generally been compared with the published one.

Insulin exerts direct, IGF-1 independent actions in growth plate chondrocytes

Insufficient insulin production or action in diabetic states is associated with growth retardation and impaired bone healing, while the underling mechanisms are unknown. In this study, we sought to define the role of insulin signaling in the growth plate. Insulin treatment of embryonic metatarsal bones from wild-type mice increased chondrocyte proliferation. Mice lacking insulin receptor （IR） selectively in chondrocytes （CartIR-/-） had no discernable differences in total femoral length compared to control littermates. However, CartIR-/- mice exhibited an increase in chondrocyte numbers in the growth plate than that of the controls. Chondrocytes lacking IR had elevated insulin-like growth factor （IGF）-IR mRNA and protein levels. Subsequently, IGF-1 induced phosphorylafion of Akt and ERK was enhanced, while this action was eliminated when the cells were treated with IGF-1R inhibitor Picropodophyllin. Deletion of the IR impaired chondrogenic differentiation, and the effect could not be restored by treatment of insulin, but partially rescued by IGF-1 treatment. Intriguingly, the size of hypertrophic chondrocytes was smaller in CartIR-/- mice when compared with that of the control littermates, which was associated with upregnlation of tuberous sclerosis complex 2 （TSC2）. These results suggest that deletion of the IR in chondrocytes sensitizes IGF-1R signaling and action, IR and IGF-1R coordinate to regulate the proliferation, differentiation and hypertrophy of growth plate chondrocytes.

On the Alternate Direction Implicit (ADI) Method for Solving Heat Transfer in Composite Stamping

Thermostamping of thermoplastic matrix composites is a process where a preheated blank is rapidly shaped in a cold matching mould. Predictive modelling of the main physical phenomena occurring in this process requires an accurate prediction of the temperature field. In this paper, a numerical method is proposed to simulate this heat transfer. The initial three-dimensional heat equation is handled using an additive decomposition, a thin shell assumption, and an operator splitting strategy. An adapted resolution algorithm is then presented. It results in an alternate direction implicit decomposition: the problem is solved successively as a 2D surface problem and several one-dimensional through thickness problems. The strategy was fully validated versus a 3D calculation on a simple test case and the proposed strategy is shown to enable a tremendous calculation speed up. The limits of applicability of this method are investigated with two parametric studies, one on the thickness to width ratio and the other one on the effect of curvature. These conditions are usually fulfilled in industrial cases. Finally, even though the method was developed under linear assumption (constant material properties), the strategy validity is extended to multiply, temperature dependant (nonlinear) case using an industrial test case. Because of the standard methods involved, the proposed ADI method can readily be implemented in existing software.

A TIME DOMAIN METHOD FOR QUASI-STATIC ANALYSIS OF VISCOELASTIC THIN PLATES

Based on the Boltzmann’s superposition principles of linear viscoelastic materials and the von K*-rm*-n’s hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelastic thin plates was given. By the Galerkin method in spatial domain, the original integro-partial-differential system could be transformed into an integral system. The latter further was reduced to a differential system by using the new method for temporal domain presented in this paper. Numerical results show that compared with the ordinary finite difference method, the new method in this paper is simpler to operate and has some advantages, such as, no storage and quicker computational speed etc.

Recent Study of Drag Embedment Plate Anchors in China

Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study of drag anchors. The techniques for measuring the trajectory and movement direction of drag anchors in soils, the techniques for measuring the moving embedment point and reverse eatenary shape of the embedded drag line, the penetration mechanism and kinematic behavior of drag anchors, the ultimate embedment depth of drag anchors, the movement direction of the anchor with an arbitrary fluke section, the reverse catenary properties of the embedded drag line, the interaetional properties between drag anchor and installation line, the kinematic model of drag anchors in seabed soils, and the analytical method for predicting the anchor trajectory in soils will all be examined. The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors, and is beneficial to improving the application of this new type of drag anchor in offshore engineering.

A TIME DOMAIN METHOD FOR QUASI-STATIC ANALYSIS OF VISCOELASTIC THIN PLATES

Based on the Boltzmann's superposition principles of linear viscoelastic materials and the von Karman's hypotheses of thin plates with large deflections, a mathematical model for quasi-static problems of viscoelastic thin plates was given. By the Galerkin method in spatial domain, the original integro-partial-differential system could be transformed into an integral system. The latter further was reduced to a differential system by using the new method for temporal domain presented in this paper. Numerical results show that compared with the ordinary finite difference method, the new method in this paper is simpler to operate and has some advantages, such as, no storage and quicker computational speed etc.

Edge crack growth of mortar plate specimens under uniaxial loading tests

In this paper, a compression-to-tension conversion technique is developed by applying predominant mode I loading test, using a servo-controlled compression system. The technique is applied to thin mortar plate specimens of different widths that include a prefabricated crack on either a single side to facilitate unilateral crack propagation, or prefabricated cracks positioned on both sides asymmetrically with respect to the specimen midpoint to facilitate bilateral crack propagation under direct tensile stress with a loading rate of 0.001 mm/s. The results show that the main pathways of unilateral crack propagation governing specimen failure are fluctuated locally, but present an approximately straight line overall in the absence of pre-existing internal defects. However, the pathways of bilateral crack propagation are relatively complex, although they present similar characteristics. Analysis results suggest that bilateral crack propagation can be basically divided into three stages, i.e. a stage of linear propagation, a stage representing deviation from the other crack, and a stage where one crack approaches either the other crack or approaches the opposite edge of the specimen, and thereby forming a continuous crack through the specimen. In addition, the stressestrain curves of bilateral crack specimens do not vary significantly around the point of peak stress prior to specimen failure, which means that the specimens do not fail instantaneously.

A METHOD OF DETERMINING BUCKLED STATES OF THIN PLATES AT A DOUBLE EIGENVALUE

A method of determining bifurcation directions at a double eigenvalue is presented by combining the finite element method with the perturbation method. By using the present method, the buckled states of rectangular plates at a double eigenvalue are numerically analyzed. The results show that this method is effective.

THE PROBABILITY STABILITY OF VISCOELASTIC PLATES

The almost sure stability of homogeneous viscoelastic platessubjected to a random wide-band stationary in-plane load isinvestigated. The viscoelastic behavior of the plate is described interms of the Bo- ltzmann superposition principle, the relaxationkernels of which are represented by the sums of exponents. On theassumption that the in-plane load is random wide-band stationaryprocess, sufficient conditions for al- Most sure stability ofviscoelastic plates are obtained by the applications of Lyapunov'sdirect method.

Direct electroless Ni-P plating on AZ91D magnesium alloy

An electroless Ni-P plating treatment was applied on AZ91D magnesium alloy to improve its corrosion resistance. Optimum pretreatment conditions and optimum bath of electroless nickel plating for magnesium alloy were found through many experiments. In order to avoid bother of pre-plating medium layer, a set of procedure of direct electroless Ni-P under the acid condition was investigated. The properties of the coating with 10% phosphorus were investigated. The results show that a coating with high hardness, low porosity and good adhesive strength is obtained. X-ray diffraction patterns show that the structure of the coating is an amorphous phase. After annealing at 400℃, the amorphous phase of Ni-P is transformed to crystalline phases, and some intermetallics as Ni3P and Ni5P2 are deposited from Ni-P solid solution along with an enhancing hardness from Hv 450 to Hv 910.

Design and Engineering Application of Direct Mixing Lubrication System for Emulsion Pipeline in Secondary Cold Rolling Mill

With the benefit fierce competition in the steel industry market in recent years,double cold reduction products have been developed towards strength improvement and thickness reduction.The traditional cold-rolling lubrication process with a fixed flow rate and concentration cannot solve the problems,which are uncontrollable plate shape and the excessive consumption of lubricating oil.Moreover,based on the analysis of the traditional direct aplication lubrication system of double cold reduction mill,a set of design scheme suitable for the emulsion pipeline direct mixing lubrication system of double cold reduction mill unit was proposed.The design completed the selection of key components,which included the static mixer and atomization nozzle selection,pump and oil pump design selection,pipeline design selection,flow type selection,pressure gauge selection,electronic control cabinet design selection and other eight aspects.Equipment of the emulsion pipeline direct mixing lubrication system of double cold reduction has been developed.Comparing with characteristics of the traditional direct aplication lubrication system,the emulsion pipeline direct mixing lubrication system was better applied to the production practice of a 1220 double cold reduction mill.The consumption of ton of steel was reduced by 9.6%.The rolling energy consumption and fuel consumption comprehensive costs decreased by 10.7%,and the strip steel section thickness difference was reduced by 19.3%.In addition,the plate shape quality defect rate decreased by 25.6%,otherwise creating a large economic benefit for the unit and promoting the application value.

不同界面下梁端直剪型锚栓钢板剪切承载力试验研究

开展梁端直剪型锚栓钢板剪切承载力加固试验研究。试验序列包含1个对比试验段、5个剪切承载力加固试验段。试验参数包括界面条件和钢板高度。结果表明:受力过程中钢板与混凝土之间的黏结界面终会剥离,不同黏结界面不影响剪切承载力;增加钢板高度和配套的直剪型锚栓数量能有效提高混凝土梁的剪切承载力。直剪型锚栓钢板剪切承载力加固存在2种机制,约束机制通过限制斜裂缝宽度提高剪切承载力,而组合受力机制通过钢板将一部分剪力直接传入支座。加固钢板高度较小时以约束机制为主,加固钢板高度较大时,2种加固机制联合发挥作用。

Direct Ni Electroless Metallization of Poly(etherimide) without Using Palladium as a Catalyst

Nickel or copper electroless metallization of polymers needs the grafting of a catalyst (palladium in the Pd(0) oxidation state) on the substrate surface to be coated. Our previous works on this topic [1-5] have allowed to develop a simple, tin-free method to attach Pd(+2) species from a palladium chloride (PdCl2) solution on any insulating surface and subsequently to reduce them, in the wet way, into the Pd(0) oxidation state. This Pd(0) state of the catalyst allows an instantaneous initiation of the Ni or Cu deposit by immersion in a plating bath. As palladium is an expensive chemical, it appears interesting to replace it by Ni(0) or Cu(0) species which are catalysts of their own ion reduction. Concerning the direct Ni electroless plating, the polymer surface (PI) was made catalytic for the electroless process by deposition (spin- coating or dipping) of an ultra-thin film of an organic nickel salt in an alcoholic solution. The chemical reduction of this salt, checked by XPS, was performed by chemical or photochemical ways and by plasma. Under these conditions, the initiation, by autocatalysis, of the Ni film deposition in an industrial plating bath was immediate i.e. without any initiation time. The film obtained was homogeneous, dense, bright, well-adhering up to thicknesses reaching

增材制造中空风冷板工艺设计与试验

为了验证增材制造技术对复杂中空风冷板的可行性,对中空风冷板模型增材制造工艺性、增材制造打印成型工艺性和粉末选择进行了分析对比。文中优选成熟AlSi10Mg铝合金打印参数完成中空风冷板的成型,并对随炉打印的试样力学性能和表面处理防护性能进行了试验验证。试验结果表明,增材中空风冷板性能可以满足产品设计使用要求。

浸镀时间对镀钯无氧铜线镀层质量的影响

采用直接镀法和扫描电子显微镜研究了影响无氧铜线镀钯层质量的因素。结果表明:浸镀时间和纳米钯粉含量对无氧铜线镀钯层质量有显著影响。当镀液中纳米钯粉的质量分数为2%、表面活性剂OP-10的质量分数为3%时,在室温浸镀15 min以上的无氧铜线表面纳米钯颗粒团聚较少,几乎无露铜现象;纳米钯粉和OP-10的质量分数分别增加至4%和6%时,在室温浸镀20 min的无氧铜线镀层质量最好。此外,当镀液温度升高至约60℃时,浸镀15 min的无氧铜线镀层不均匀,漏铜现象明显。在450℃真空退火后,镀钯铜线的镀层界面结合强度和平整度提高。

玉米锥形脱粒装置仿真优化设计

我国北方地区常用的玉米籽粒直收收获机在脱粒工序中存在脱粒元件对果穗冲击强度过大的问题,为此设计一种低损高效的玉米锥形脱粒分离装置。对脱粒滚筒结构进行分析,建立果穗与脱粒凹板间的接触模型,确定滚筒最优参数的取值范围。通过EDEM软件对不同参数组合的脱粒分离装置进行仿真优化试验。结果表明,当脱粒滚筒锥角为8°,凹板选用左向圆管型结构,滚筒转速为400 r/min时,脱粒效果最佳,并与传统式脱粒滚筒相比,起脱段脱粒元件对果穗的碰撞力由284 N降低为234 N,碰撞反力由202.54 N降低为171.52 N,从而验证锥形脱粒滚筒具有降低对果穗冲击强度的特性。利用ADAMS软件对锥形脱粒装置进行运动学及动平衡仿真分析,验证研究成果的可靠性及理论可行性,且系统产生的不平衡惯性力符合农业机械设计要求。为后续玉米脱粒分离装置的创新设计和结构改进提供理论参考。

公路桥梁梳齿板伸缩装置的优化设计

为减少某型梳齿板伸缩缝的制造成本,利用有限元ANSYS Workbench平台对结构进行轻量化设计。首先对100%开口极限工况下的梳齿板伸缩缝进行静强度和刚度验算。其次根据行业标准对实际极限工况下的梳齿板伸缩装置进行承载力试验,验证仿真计算的正确性。最后选择对伸缩装置重量、应力和变形影响较大的参数作为设计变量,以装置的许用应力与变形作为约束条件,装置的总重量为优化目标,采用两种不同的优化方法对其进行轻量化设计并进行强度刚度验证。优化结果表明:优化后的总重量减轻38.06%,优化效果显著,且符合该装置的强度和刚度要求。互相对比两种优化结果,验证了方法的可行性及可靠性,为研究桥梁伸缩装置结构轻量化设计提供了参考。