Form Evaluation of Free-Form Shells by Using Bending Strain Energy Ratio

2016 ◽  
Vol 57 (4) ◽  
pp. 267-274
Author(s):  
H. Utebi ◽  
K. Yamamoto
Keyword(s):  
Strain Energy ◽  
Energy Ratio ◽  
Free Form ◽  
Bending Strain ◽  
Form Evaluation ◽  
Strain Energy Ratio

Analysis on vibration energy concentration of the one-dimensional wedge-shaped acoustic black hole structure

2018 ◽  
Vol 29 (10) ◽  
pp. 2137-2148 ◽  
Author(s):  
Xi Li ◽  
Qian Ding
Keyword(s):  
Black Hole ◽  
Strain Energy ◽  
Energy Ratio ◽  
Energy Concentration ◽  
Vibration Energy ◽  
Maximum Height ◽  
The One ◽  
Hole Structure ◽  
Hole Effect ◽  
Strain Energy Ratio

The transverse vibration energy of a plate with a wedge-shaped profile can be trapped by acoustic black hole effect to its edge portion, in case the wedge thickness is diminished according to the power-law h( x) =  εxm with m ≥ 2.0. The acoustic black hole effect exhibits potential ability for passive vibration control and energy harvesting. In this article, the transfer matrix method is adopted to establish and solve the dynamical model of acoustic black hole structure. Energy ratio is defined as a ratio of the energy trapped within the edge portion to that of the whole wedge, to illustrate the energy concentration effect. Analyses show that both the strain energy ratio and kinetic energy ratio of the acoustic black hole structure achieve the minimum when the wedge is in resonances, although these two kinds of energy come to peaks at this case. However, in the case of small length of the edge portion, the strain energy ratio reaches the highest peaks at the second and higher resonances, rather than at the first one. Generally, the best effect of energy concentration occurs when m ranges from 2.5 to 3.0. Reducing the truncation thickness and increasing the maximum height can improve the energy trapping.

Helical Domain Patterns in Tube Configurations: Effect of Geometry Length Scales

2011 ◽  
Vol 172-174 ◽  
pp. 1090-1095 ◽  
Author(s):  
R.H. Zhou ◽  
Qing Ping Sun
Keyword(s):  
Strain Energy ◽  
Optical Measurement ◽  
Strong Support ◽  
Martensite Phase ◽  
Helical Domain ◽  
Self Organized ◽  
Bending Strain ◽  
Strain Martensite ◽  
Tube Geometry

Superelastic NiTi polycrystalline tubes, when subjected to quasi-static stretching, transform from an initial austenite phase to a high-strain martensite phase by the formation and growth of a macroscopic self-organized helical domain as deformation progresses. This paper performed an experimental study on the effects of the externally applied stretching and tube geometry (length L, wall-thickness h and tube radius R) on the martensitic helical domains in the tubes under very slow (isothermal) stretching. The evolution of the helical domains with the applied strain in different tube geometries are quantified by in-situ optical measurement. We demonstrate that the shape of the self-organized helical domain and its evolution are governed by the competition between bending strain energy and domain front energy in minimizing the total energy of the tube system. The former favors a long slim helical domain, while the latter favors a short fat helical domain. The experimental results provide a strong support to the recently developed theoretical relationship.

Exploration of Local Blade Motions During Blade Shaping for Thick Layered Foam Cutting

2004 ◽  
Author(s):  
J. J. Broek ◽  
A. Kooijman
Keyword(s):  
Strain Energy ◽  
Cutting Tool ◽  
Cutting Speed ◽  
General Rule ◽  
Free Form ◽  
Linear Change ◽  
Minimum Strain Energy ◽  
Blade Cutting ◽  
Tool Position ◽  
Cutting Direction

The FF-TLOM (Free Form Thick Layered Object Manufacturing) technology is a Rapid Prototyping process based on flexible blade cutting of polystyrene foam. The heated blade is shaped by three parameters, which allows an infinite amount of minimum strain energy blade shapes with none, one or two inflexions. In the shaping domain stable and unstable blade shapes can exist. Stable shapes are defined as curves with none and one-inflexion and are applied for operational cutting of foam layers with the FF-TLOM technology. The tool motions are generated from the static tool poses and are calculated for a linear change of the flexible blade, when the cutting tool moves from one tool position to the next. The cutting blade is positioned to the foam slab with help of a point relative positioned on the flexible blade. The tool frame is positioned with a point fixed relatively to the tool frame. During the tool motions the blade curvature is changed and will introduce a shift of the half way point fixed on the blade (especially in the case of asymmetrical support inclinations and high curvature). Next the local displacement of the blade points in the bending plane of the blade due to blade shaping and tool pitching are quantified during the tool motions. These displacements induce an angle of attack of the blade in cutting direction, and will influence cutting speed and cutting accuracy. The quantification software is developed and will be used in the future for an overall prediction of the total tool curve displacements due to blade shaping, such as roll, pitch, yaw and linear positioning motions of the tool. A general rule for FF-TLOM cutting is minimization of all tool motions, which are not related to the forward cutting motion.

Study on Characteristics of Energy for Hard Roof Fracture in Island Workface

2013 ◽  
Vol 734-737 ◽  
pp. 694-697
Author(s):  
Xu Feng Pang ◽  
Ke Xue Zhang
Keyword(s):  
Strain Energy ◽  
Typical Case ◽  
Energy Characteristics ◽  
Hard Roof ◽  
Coal Bump ◽  
Bending Strain ◽  
Before And After ◽  
Mechanical Models

According to the characteristics of the island workface with hard roof, various mechanical models of hard roof in island workface are established, to analyze energy characteristics of hard roof before and after the first fracture in island workface with all round gobs, derived their simplified formulas of bending strain energy for hard roof before and after the first fracture, and using these formulas to estimate the bending strain energy for the typical case of coal bump, reveals the energy cause of coal bump and verify the validity of these formulas.

Optimization Research on Geometric Parameters of Scallop-Shaped Lattice Shells

2015 ◽  
Vol 724 ◽  
pp. 192-196
Author(s):  
Na Li ◽  
Ren An Chang ◽  
Wei Zong ◽  
Qi Hang Yu
Keyword(s):  
Mechanical Properties ◽  
Strain Energy ◽  
Geometric Parameters ◽  
Free Form ◽  
Spatial Structures ◽  
Shaped Surface ◽  
Minimum Strain Energy ◽  
Optimal Values ◽  
Lattice Shells

<p>Free-form and bionic spatial shells are popular in the area of spatial structures. Scallop-shaped surface is the product of evolution and a kind of spatial shells that can satisfy the mechanical requirements. Based on the scallop-shaped lattice shells, this paper focused on the optimization of geometric parameters. The principle of minimum strain energy was applied to conclude the influence law of the geometric parameters on mechanical properties. Finally the optimal values of geometric parameters were obtained. The results show that the optimization of geometric parameters presents the integrated significance to improve scallop-shaped lattice shells.</p>

Research on Feasibility and Applicability of Delamination Localization Methods for Composite Laminated Beams

2014 ◽  
Vol 599-601 ◽  
pp. 92-95
Author(s):  
Hang Ma ◽  
Ping Lu ◽  
Tao Jiang ◽  
Sheng Feng Shi ◽  
Jian Bin Wei ◽  
...  
Keyword(s):  
Strain Energy ◽  
Damage Index ◽  
Energy Difference ◽  
Laminated Beams ◽  
Modal Strain Energy ◽  
Laminated Beam ◽  
Modal Strain Energy Method ◽  
Response Method ◽  
Strain Energy Ratio ◽  
Delamination Damage

The feasibility and applicability of delamination damages localization methods with various defined damage indexes for the damaged composite laminated beam were studied. The results indicate that, for the modal strain energy method, damage indexes defined by strain energy difference are more effective to locate the delamination damage than that of strain energy ratio. For energy response method, damage index defined by the second difference can effectively locate the delamination damage in the composite laminated beams.

Free Vibration and Stability of a Spinning Disk-Spindle System

1999 ◽  
Vol 121 (3) ◽  
pp. 391-396 ◽  
Author(s):  
R. G. Parker ◽  
P. J. Sathe
Keyword(s):  
Free Vibration ◽  
Strain Energy ◽  
Natural Frequencies ◽  
Vibration Modes ◽  
Modal Strain Energy ◽  
Spindle System ◽  
Disk Rotation ◽  
High Speeds ◽  
Elastic Disk ◽  
Strain Energy Ratio

This work examines the free vibration and stability of a spinning, elastic disk-spindle system. The extended operator formulation is exploited to discretize the system using Galerkin’s method (Parker, 1999). The coupled vibration modes of the system consist of disk modes, in which the disk dominates the system deformation, and spindle modes, in which the spindle dominates the system deformation. Both the natural frequencies and vibration modes are strongly affected by disk flexibility. If the membrane stresses associated with disk rotation are neglected then the system exhibits flutter instabilities, but these instabilities are not present when membrane stresses are modeled. Natural frequency veering between disk and spindle frequencies is prominent at low speeds and substantially affects the spectrum and stability. No veering is observed at high speeds where rotational stress stiffening diminishes disk-spindle coupling and causes the natural frequencies to converge to those of a rotating spindle carrying a rigid disk. Changes to the vibration modes are examined in terms of a strain energy ratio measuring the contribution of the disk strain energy to the total modal strain energy.

scholarly journals Experimental Study on the Law of Energy Dissipation and Damage in Coal Body Based on Local Tensile-Sliding Effect

2021 ◽  
Author(s):  
Xiangfeng Lv ◽  
Xinyue Li ◽  
Yishan Pan
Keyword(s):  
Energy Consumption ◽  
Energy Dissipation ◽  
Strain Energy ◽  
Damage Accumulation ◽  
Type Specimen ◽  
Equilibrium Degree ◽  
Coal Deformation ◽  
Expansion Stage ◽  
Equal Amplitude ◽  
Strain Energy Ratio

Abstract The slippage initiation and induced instability of roadway surrounding rock are highly likely to cause dynamic disasters, severely influencing the safety production of mining. With the optical-mechanical monitoring test of the deformation localization of energy dissipation, this study established the optical index of coal deformation equilibrium degree under load, and obtained the evolution law of coal deformation equilibrium degree. After analyzing the relationship between tensile-sliding effect and mechanical behavior of coal deformation field, it proposed the strain energy ratio coefficient. The results indicate that the strength reduction of coal body is affected by the deformation accumulation of loading displacement field. The sliding displacement of the stable sliding type specimen occurs 5.5s earlier than tensile displacement，which is 4.4s longer than the instantaneous instability type specimen. The instability type of coal is closely related to the tangent angle of the strain energy ratio coefficient and the damage persistence characteristics. The damage accumulation of stable equal amplitude contributes to the stable failure, and the damage accumulation of interval equal amplitude influences the instantaneous instability development. The fracture expansion stage is the main stage of energy consumption damage accumulation. That is, the main energy consumption damage accumulation stage of the stable slip coal is the stable crack expansion stage, with the damage proportion of 35.89%, while the damage proportion of instantaneous instability coal in the unsteady crack expansion stage is 84.226%. The study provides theoretical reference for the fracture law and risk monitoring of coal slippage.

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