Folding responses of origami-inspired structures connected by groove compliant joints

Folding responses of a set of notch-type compliant joint candidates are first numerically explored before the victorious one is implemented in actuating the deployment of Miura origami-inspired plate structure. The considered notch-type compliant joints are groove, elliptical holes, rectangular holes, and outside LET types. The exploration and examination of the kinematic and dynamic characteristics of these joints include performance indicators such as stress contour, load-deformation, moment-angle, and stiffness-angle relationships for different geometric parameters, with a specific interest in their hysteretic behaviors. Considering various performance features, the groove joints have been identified as the most suitable to be employed as the Miura origami-inspired hinge. The Miura origami-inspired plate folding behaviors are further explored considering various numbers and placements of groove joints. It has been found that the Miura plate performs better with the groove joint compared to that without one and that the single and double groove joint modes are inter-correlated. The study offers a comprehensive understanding of the effects of geometrical variation of numerous compliant joints on the folding behaviors as well as the further implementation of the victorious one in actuating the deployment of the Miura origami-inspired plate structure in accordance with the number and location of the joint.

Study on Broken Floor Rock Mass by Mining Underground Pressure

As the dangerous level of floor water inrush in Chinese coal field is becoming more and more serious annually, the widely used formulas of broken floor rock mass are belonged to nonlinear type or empirical type. However, they are not well conformed to the practical situation and including mining underground pressure. The biggest depth of broken floor rock mass and the length of gob-floor or mining-floor until the maximum broken floor location are expressed by theoretical formulas on integrity theory. Taking a mining face in Chinese Anhui Province as the object, the relationship between broken floor rock mass and mining underground pressure is studied by numerical simulation, the theoretical analysis, and the DC exploration. The peak and scope of broken floor rock mass will enlarge until reaching limit value with the increasingly advanced distance. The mining gob stress contour is saddle-shaped, and its growing speed is becoming slower, so the 180 m coal mining face has reached the sufficient mining stage. Wave velocity of broken floor rock mass from 0 m to 16 m is greatly decreased by the mining disturbance, and it is basically conformed to theoretical formula and practical situation. The results can be relatively better used in the pressure mining of the Ordovician limestone, because it can provide some safe guarantee for mining deep coal seam.

Optimization of Test Procedure for Simulation of Paper Laminate in Axial Loading Conditions Using FRANC2D and CASCA

In present investigation, an attempt was made to optimise the peak stress for paper laminate composite using FRANC2D software. It was observed that the laminate having the triangular geometry supposed to be most appropriate as it has the lowest value of peak stress contour compared to other models like parallel strip, up-down tapered and down-up tapered. The minimum peak stress was observed for the samples having triangular geometry while the maximum was observed for down-up tapered samples. Therefore, the hypothesis adopted to use in-built materials with variables reinforcement area and strip geometry and length in the FRANC2D software to optimize the sample geometry and then apply it to the paper laminate by considering its mechanical properties might be use to optimize the peak stress of paper laminate composite in tensile loading conditions. It was also observed a length of one-quarter of the length of the plane strip, might be the optimum length of the paper laminate samples. However, it feels that, the above model can be further modified considering a more significant mechanical properties as well as different sample geometries.

Analysis of Indentation Test Using Solid Works Simulation

The finite element analysis of spherical indentation was conducted using the SolidWorks simulation software. The relationship between the load and indention was determined, and comparison with the Hertzian solution was made. In this study, spherical indenters of diameter 5, 10 and 15 mm were used to assess the effect of indenter radius on indentation response at a specified load. The outcome of our study shows that the resulting load-indentation response does not closely correlate; as a result, a difference of 21.2% was observed between the hertz solution and simulated results. The increase in diameter was observed to be associated with the corresponding decrease in indentation depth and the indentation stress. The von Mises stress contour at maximum load was analysed and was observed to be the highest on the indented surface beneath the indenter. The resultant displacement contour shows a uniform displacement distribution.

Finite Element Analysis of Fiber Cement Corrugated Roofing Sheet under Bending

The study presents a numerical model for evaluation of the stresses in corrugated sheets under bending. The numerical analysis was performed from a three dimensional finite element model. From the analysis, the most intense tensional stress occurs in the trough and bottom surface of the corrugated sheet. While the most intense value of compressive stress occur in the crest and top surface of the sheet. Based on the principal stress contour diagram, the researcher also observed that the maximum uniformly distributed load carrying capacity of the fiber-cement corrugated sheet under bending, considering the linear material properties is 710N.

Study on Stressing State and Failure Criterion of Concrete-Filled Stainless Steel and Steel Tubular Column

In this paper, the mechanical characteristics of concrete-filled stainless steel and steel tubular (CFSSAST) columns under axial and eccentric loads are analyzed by using the theory of structural stressing state. Firstly, the sum of generalized strain energy density (GSED) values of the short column at every load value (Fj) is normalized as Ej,norm to describe the structural stressing state. Then, according to Mann–Kendall (M-K) criterion and the natural law from quantitative change to qualitative change, the transition of stressing state is distinguished, which leads to the update of failure load. Then, the corresponding finite element models are established, and the accuracy of the models is verified by the experimental data, and the stress contour maps are analyzed by simulation data. Finally, the simulation data are used to perform parameter analysis. This study explores a new method to reveal the invisible working characteristics of structures and provides a new reference for the study of similar structures.

Topology Optimization of Frame of the Rack System

Integration of the Electronics modules in the rack system has been very challenging and critical in nature. The functionality of the electronics module is of prime importance for the operation on any system or subsystem. In many cases where these electronics systems housed in a rack system which in turn mounted in aircraft fuselage make functioning of the system more severe. This paper deals with design optimization of frame of rack structure in line with increasing demand of more robust and light structure with features of high stiffness and structural integrity. Aerospace industries employ topology , size and shape optimization technique and have reported significant structural performance gains as a result ,This report deals with the topology optimization of frame of rack structure has been performed using OptiStruct software. The main objective is to find the optimal topology of frame of the rack. The rack structure has undergone the first level of optimization, in other word it is called finite element analysis with inertia loading condition which presents the stress contour with varying stress level, the stress contour highlight the maximum and minimum stress level in the structure which gives the first level of information about the material requirement within the structure. Topology optimization being the part of the structural optimization is the extended domain of the structural analysis where optimum placement of the material in the design space is the prime focus. The design space is a geometrical space where material alteration is effected to achieve the design objective. Topology optimization problems utilize the firmest mathematical basis, to account for improved weight-to-stiffness ratio and perceived aesthetic appeal of specific structural forms, enabling the Solid Isotropic Material with Penalization (SIMP) technique. Structural topology optimization is a technique for finding the optimum number, location and shape of opening with in the given design space of the rack structure to the series of loads and the boundary conditions. A range of topology of rack frame is obtained by setting varying the target volume fraction and an optimum topology of the frame is selected by satisfying stress to weight ratio requirement and manufacturing constraint.

Impact of Modified Spacer on Flow Pattern in Narrow Spacer-Filled Channels for Spiral-Wound Membrane Modules

A modified spacer, which was constructed with arched filaments and zigzag filaments, was designed to improve vortex shedding and generate a directional change in flow patterns of membrane modules, especially in the vicinity of the feed spacer filament, which is most affected by fouling. A unit cell was investigated by using a three-dimensional computational fluid dynamics (CFD) model for hydrodynamic simulation. The results of CFD simulations were carried out for the fluid flow in order to understand the effect of the modified spacer on vortices to the performance of arched filaments at different distances. From 2D velocity vectors and shear stress contour mixing, the flow pattern and dead zone flushing were depicted. The ratio of low shear stress area to the total area increased with the inlet velocity closed to 20%. The energy consumption with respect to flow direction for the arched filament was 80% lower than that in the zigzag filament. Compared with previous commercial spacers’ simulation, the friction factor was lower when the main flow was normal to the arched filament and the modified friction factor was close to the commercial spacers. The homogenization was realized through the flow pattern created by the modified spacer.

New Method to Design Coal Pillar for Lateral Roof Roadway Based on Mining-Induced Stress: A Case Study

The traditional method to design coal pillar for lateral roof roadway was established based on the mining-induced strata movement contour which is considered as a straight line, while ignoring the variations of the internal strata deformation law as well as stress distribution characteristics. In order to make up for this deficiency, in this study, evolution of mining-induced stress in the overlying strata was simulated using physical and numerical simulations, and a method to design coal pillar for lateral roof roadway based on mining-induced stress was proposed. The results indicate that the stress of the overlying strata is redistributed during excavation, and the stress distribution can be divided into a stress-relaxation area, a stress-concentration area, and an in situ stress area. The contour line of 1.05 times the in situ stress is used to define the mining-induced stress contour. Stress inside the contour is redistributed while outside the contour the overlying strata are still within the in situ stress area. Mining-induced stress contour presents a concave-upward type from coal seam to the overlying strata that cannot be merged into a straight one due to their different characteristics of movement and deformation. With this in mind, this study proposed a method to design the width of coal pillar for lateral roof roadway according to the mining-induced stress contour. According to mining-induced stress contour, the width of coal pillar for lateral roof roadway of longwall panel 31100 is 160 m, and the maximum deformation of the roadway is 270 mm. The new method can definitely meet engineering demands.

Mechanical Behavior of Assembled Steel Dampers with Optimized Shapes

A metallic shear damper is developed with the shape optimized by stress contour lines to mitigate the stress concentration, reduce the effect of hot welds, and improve the efficiency of energy consumption. The stress contour line is defined according to the J2 plasticity theory, where the micro units yield simultaneously. To demonstrate the effectiveness of the proposed shape-optimization method and the correctness of design formulas, detailed FEM models were built for nine dampers. And the influence of the axial loads was studied as well. Finally, seven damper specimens were fabricated and tested quasi-statically, including six optimized dampers and one with a rectangle shape as a comparison. Both numerical simulation and physical tests demonstrate that the distribution of plastic deformation is more uniform, and the accumulated equivalent plastic strain is reduced significantly, compared with the non-optimized damper. The proposed metallic shear damper has a good low-cycle fatigue capability and a stable energy-dissipation capacity. The stiffness and strength design equations predicted the specimen performance very well.