Anti-plane deformations around arbitrary-shaped canyons on a wedge-shape half-space:moment method solutions

The wave propagation behavior in an elastic wedge-shaped medium with an arbitrary shaped cylindrical canyon at its vertex has been studied.Numerical computation of the wave displacement field is carried out on and near the canyon surfaces using weighted-residuals(moment method).The wave displacement fields are computed by the residual method for the cases of elliptic,circular,rounded-rectangular and flat-elliptic canyons,The analysis demonstrates that the resulting surface displacement depends,as in similar previous analyses,on several factors including,but not limited,to the angle of the wedge,the geometry of the vertex,the frequencies of the incident waves,the angles of incidence,and the material properties of the media.The analysis provides intriguing results that help to explain geophysical observations regarding the amplification of seismic energy as a function of site conditions.

Flow around three rectangular cylinders arranged in connected and separated Y-shape

Characteristics of cross flow around three rectangular cylinders with two aspect ratios of breadth to width arranged in connected and separated Y-shape at various angles of incident flow were studied by means of force measurement in a wind tunnel. Flow visualizations with smoke-wire technique for typical cases were also given. Different types of flow patterns were formed for individual models at different angles of incident flow. From the results of fluctuating velocity measurement in the wake, features of vibration were determined. It shows that as the wind blows along the lines of one limb or rectangular cylinder of the model, oscillation is weak, whereas when the wind blows along the bisector lines of two limbs or cylinders, strong vibration is observed. It is associated with the regular vortex shedding.

FAST ACCURATE PREDICTION OF BLANK SHAPE IN SHEET METAL FORMING

By using the Finite Element Inverse Approach based on the Hill quadratic anisotrop-ically yield criterion and the quadrilateral element, a fast analyzing software-FASTAMP for the sheet metal forming is developed. The blank shapes of three typical stampings are simulated and compared with numerical results given by the AUTOFORM software and experimental results, respectively. The comparison shows that the FASTAMP can predict blank shape and strain distribution of the stamping more precisely and quickly than those given by the traditional methods and the AUTOFORM.

Closed-form solutions for free vibration of rectangular FGM thin plates resting on elastic foundation

This article presents closed-form solutions for the frequency analysis of rectangular functionally graded material (FGM) thin plates subjected to initially in-plane loads and with an elastic foundation. Based on classical thin plate theory, the governing differential equations are derived using Hamilton's principle. A neutral surface is used to eliminate stretching-bending coupling in FGM plates on the basis of the assumption of constant Poisson's ratio. The resulting governing equation of FGM thin plates has the same form as homogeneous thin plates. The separation-of-variables method is adopted to obtain solutions for the free vibration problems of rectangular FGM thin plates with separable boundary conditions, including, for example, clamped plates. The obtained normal modes and frequencies are in elegant closed forms, and present formulations and solutions are validated by comparing present results with those in the literature and finite element method results obtained by the authors. A parameter study reveals the effects of the power law index n and aspect ratio a/b on frequencies.

Shape ratio effects on the mechanical characteristics of rectangular prism rocks and isolated pillars under uniaxial compression

Isolated pillars in underground mines are subjected to uniaxial stress,and the load bearing cross-section of pillars is commonly rectangularly shaped.In addition,the uniaxial compression test(UCT)is widely used for determining the basic mechanical properties of rocks and revealing the mechanism of isolated pillar disasters under unidimensional stress.The shape effects of rock mechanical properties under uniaxial compression are mainly quantitatively reflected in the specific shape ratios of rocks.Therefore,it is necessary to study the detailed shape ratio effects on the mechanical properties of rectangular prism rock specimens and isolated pillars under uniaxial compressive stress.In this study,granite,marble and sandstone rectangular prism specimens with various height to width ratios(r)and width to thickness ratios(u)were prepared and tested.The study results show that r and u have a great influence on the bearing ability of rocks,and thin or high rocks have lower uniaxial compressive strength.Reducing the level of r can enhance the u effect on the strength of rocks,and increasing the level of u can enhance the r effect on the strength of rocks.The lateral strain on the thickness side of the rock specimen is larger than that on the width side,which implies that crack growth occurs easily on the thickness side.Considering r and u,a novel strength prediction model of isolated pillars was proposed based on the testing results,and the prediction model was used for the safety assessment of 179 isolated pillars in the Xianglu Mountain Tungsten Mine.

Influence of Axial Feeding on Hydroforming of Aluminum Alloy Tubular Part with Rectangular Section

The hydroforming experiment of aluminum tubular part with rectangular section was carried out to investigate influence of axial feeding on thickness distribution and calibration pressure of the corner.Thickness distribution and relation between corner radius and internal pressure were analyzed.The influence of lubricant was discussed.Microstructure and hardness of different region were observed.It is shown that thickness reduction in the transition region between the corner and center region is the biggest.Friction condition has influence both on the thickness distribution and calibration pressure of the corner.As the increase of the axial feeding,the calibration pressure is decreased.There is only little change for the microstructure,but the hardness is increased by 23.3% for the transition region.

Shape Optimization for A Conventional Underwater Glider to Decrease Average Periodic Resistance

As a type of autonomous underwater vehicle(AUV),underwater gliders(UG)are getting increasing attention in ocean exploration.To save energy and satisfy the mission requirements of a longer voyage,shape optimization for UGs has become a key technique and research focus.In this paper,a conventional UG,including its fuselage and hydrofoil,is optimized,which aims to decrease the average resistance in one motion cycle.To operate the optimization progress for the complex object,multiple free form deformation(FFD)volumes are established for geometric parameterization.High-fidelity simulation models are employed for objective function evaluation and gradients calculation.And sequential quadratic programming(SQP)method is adopted as an optimization algorithm.The optimization results show that there exists a UG with symmetrical and non-horizontal hydrofoils that has lower resistance.

Plasma-Jet Forming of Sheet Metal Shapes

Plasma-jet forming is a newly proposed flexible sheet metal forming process. A non-transferred arc plasma torch is used as a controllable heat source to produce internal stress in sheet metals, causing plastic deformation without the necessity of hard tooling. This method has potential for rapid prototyping of sheet metal parts by reducing development costs and lead times. A robotic system has been used to perform simple linear bends in several different alloys. In order to develop a controllable process and to improve the forming accuracy, the effects of various process parameters on the obtained shape changes and on the resulting structure and properties have been studied. The overall goal is to understand the roles of the forming parameters and their inter-relationship in optimizing the forming procedure-a high forming speed without damage to the material structure or properties.

Modeling of the Shape Forming of Composite Roll

A shape modeling of spray formed composite roll, which is utilized to predict the shape and dimension of roll during spray forming process, is developed in this paper. The influences of the principal spray forming parameters, such as the spatial distribution of melt mass flux, spray distance, rotating and translating speeds of substrate bar etc. , on the geometry and dimension of spray formed product were investigated.

Informal Settlements： A Shape Grammar Approach

Informal urban development is seldomly covered in academic studies or professional architectural training. This article sets forth the first stage of a novel study that observes the informal city using the methodology of analysis of architecture called shape grammars. The idea is to recognize peculiarities in the occupation of the land and the volumetric features of the buildings. Rocinha favela, in Rio de Janeiro, Brazil, is taken as a case study with the primary aim of extrapolating a set of rules for its morphological features so that these rules can be used to generate new shapes, whilst bearing in mind the issues of adaptation and transformation which are so characteristic of informal settlements. There is some expectation that this study may help improve the housing and public space in the favela and enable new housing programs to observe the way the buildings and different architectural elements combined, forming a new channel of interchange with the spatial organization of the favela.

Shape formation of closed-cell aluminum foam in solid–liquid–gas coexisting state

The mold pressing process was applied to investigate the formability of closed-cell aluminum foam in solid–liquid–gas coexisting state.Results show that the shape formation of closed-cell aluminum foam in the solid–liquid–gas coexisting state was realized through cell wall deformation and cell movement caused by primary α-Al grains that slid,rotated,deformed,and ripened within cell walls.During formation,characteristic parameters of closed-cell aluminum foam were almost unchanged.Under proper forming conditions,shaped products of closed-cell aluminum foam could be fabricated through mold pressing.

Commuting Structure Jacobi Operator for Real Hypersurfaces in Complex Space Forms

Let M be a real hypersurface of a complex space form with almost contact metric structure (φ,ξ,η,g). In this paper, we prove that if the structure Jacobi operator Rξ=(·,ξ) ξ is φ▽ξξ-parallel and Rξ commute with the shape operator, then M is a Hopf hypersurface. Further, if Rξ is φ▽ξξ-parallel and Rξ commute with the Ricci tensor, then M is also a Hopf hypersurface provided that TrRξ is constant.

Quantifying.Associations among Dimensions of Ears and Their Form Factors in Maize(Zea Mays)Using Dimensional Analysis

Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars were collected from field experiments, and ear length(L), diameter(D), area(S) and volume(V) were recorded for individual ears, kernel weight per ear also recorded for a portion of the examined ears. Following principles of dimensional analysis, 8 theoretical equations of 3 sets,which relate ear higher dimensions to its length and diameter, were developed and parameterized and validated with the field observations. The 3 optimized equations showed that the shape of ears in maize can be featured with 3 dimensionless form factors, namely diameter-to-length ratio(c=D/L), areal form factor(b=S/L/D), and volumetric form factor(a=V/L/D/D). Statistically,all of them were significantly different among cultivars, and a's values varied from 0.582 to 0.612, and b's 0.839-0.868, and c's 0.242-0.308. Volumetric form factor and areal form factor could estimate precisely ear volume and area respectively, but diameter-to-length ratio was not suitable to estimate ear diameter by its length. Ear volume explained almost all variation of ear kernel weight and product L*D*D did the same substantially. Dimensional analysis proved to be promising in understanding relationship among morphological traits of ears in maize. Its application in crop researches should improve our knowledge of the physical properties of crop plants.

Recognition in Shape and Form’s Characteristics of Japanese&Vietnamese Traditional Daily Products

This paper presents the major analyses carried out on shape and form’s characteristic database from Japanese and Vietnamese traditional daily products(TDPs).The aim of the research is to recognize the vital specifications representing for a national style by comparing two different countries together.By using Quantification Theory Type III and Cluster analysis,firstly,the analyses were undergone separately for Japanese and then Vietnamese product data in succession so that a view of general direction for each country was caught.The result showing a difference in scale of“Complexity”and“Specification”axis between Japan and Vietnam leads to performance of the analysis done on combine database of the two countries to get a clearer view of correlation between them.However,the biggest difference between the two countries lies in“Form”(Geometric—Organic)axis.Continuously,for studying more deeply into outline of product shape,the main ratios that affect the appearance or gorgeousness of product’s outline were taken into account and analyzed.By comparing this result to the previous ones,finally a wider and more detail perspective of Japan and Vietnam shape’s specification in a mutual relationship was discovered.

ELECTRON OPTICS OF VARIABLE RECTANGULAR SHAPED BEAM LITHOGRAPHY SYSTEM D J-2

The electron optical column for the variable rectangular-shaped beam lithographysystem DJ-2 is described,with emphasis on the analysis of the optical configuration and theshaping deflection compensation.In this column the variable spot shaping is performed with aminimum number of lenses by a more reasonable optical scheme.A high-sensitivity electrostaticshaping deflector with sequential parallel-plates is implemented for high-speed spot shaping.With a precise linear and rotational approach,the spot current density,the edge resolution aswell as the position of spot origin remain unchanged when the spot size varies.Experiments showthat the spot current density of over 0.4 A/cm^2 is obtained with a tungsten hairpin cathode,andthe edge resolution is better than 0.2μm within a 2×2 mm^2 field size.

Digital Image Correlation Using Specific Shape Function for Stress Intensity Factor Measurement

The stress intensity factor (SIF) is a critical parameter associated with the fracture behaviour of materials. In this paper, we select the displacement function around a crack tip as the shape function of the digital image correlation (DIC), which makes it possible to directly calculate the SIF by the correlation scheme. Moreover, we use a non-rectangular subset, which can reduce the influence of plastic deformation and crack width on the DIC measurement accuracy. We measured the SIF of a mode I crack in a super-hard aluminium alloy specimen to verify the performance of the proposed method. Our experimental results show that a DIC with a specific shape function can be used to accurately and efficiently calculate the SIF. Furthermore, we also present a practical application of our proposed method for determining the SIF, crack propagation angle and crack tip displacement. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

工字形钢梁-矩形钢管柱单向螺栓节点抗弯承载力理论计算方法

针对工字形纯钢梁和钢-混凝土组合梁分别与矩形钢管柱和矩形钢管混凝土柱采用单向螺栓(也称单边拧紧螺栓)连接形成的4种节点形式,对其在弯矩作用下的受力机理及破坏模式进行分析,讨论导致节点失效的因素。总结节点在弯矩作用下的9种失效模式,包括:单向螺栓拉断、端板受弯屈服、矩形钢管柱壁翼板受拉屈服、矩形钢管柱壁翼板受压屈服、矩形钢管柱壁腹板受压屈曲、混凝土楼板局部压溃、钢筋屈服、矩形钢管柱内混凝土局部压溃、矩形钢管柱壁腹板受压屈服,进而基于破坏模式给出节点各组件承载力的计算公式。对4种节点在不同破坏模式下的正弯矩承载力和负弯矩承载力进行分析,给出节点承载力计算公式。将节点抗弯承载力的理论计算结果与试验结果进行对比,验证理论计算方法的可靠性。