A Flexure-Based Displacement Reducer Capable of Achieving Very Large Reduction Ratio

2021 ◽  
Author(s):  
Houqi Wu ◽  
Guimin Chen
Keyword(s):  
Element Model ◽  
Reduction Ratio ◽  
Large Reduction ◽  
Magnetostrictive Actuators ◽  
Limited Output ◽  
Bridge Type ◽  
The Difference ◽  
Kinetostatic Model ◽  
The Finite Element Model ◽  
Very High

Abstract Piezo actuators and giant magnetostrictive actuators are widely used in micropositioning and micromanipulating devices. Due to their limited output stroke, flexure-based displacement amplifiers are usually employed to meet the large-stroke requirements. Although amplifiers increase the stroke of the actuators, they lower the resolution of the motion, making it difficult to obtain positioning of nanometer or even sub-nanometer resolution. To achive very high resolution from these actuators, a compact flexure-based displacement reducer, which shows the capability of obtaining very large reduction ratio, is proposed in this work. The reducer contains two bridge-type flexure mechanisms connected in a way that the output of the reducer equals the difference of the outputs of the two mechanisms (thus is called the bridge-type differential displacement reducer). If the two bridge-type flexure mechanisms are identical, no matter how large the input is, the output will always be 0, indicating an infinite reduction ratio theoretically. Therefore, introducing a slight difference between the two mechanisms can yield a very large reduction ratio. A kinetostatic model for the reducer is developed, base on which a reducer exhibiting a reduction ratio of 100 is designed and prototyped. The results of the kinetostatic model, the finite element model and the experiment agree well with each other, validating the effectiveness of the proposed reducer and the correctness of kinetostatic model.

The Effects of Geometrical Factors on the Step-Up Ratio in Piezoelectric Transformer

2007 ◽  
Vol 539-543 ◽  
pp. 3319-3325
Author(s):  
Man Soon Yoon ◽  
T.S. Yoon ◽  
J.R. Kim ◽  
Y.G. Choi ◽  
Soon Chul Ur
Keyword(s):  
Element Model ◽  
Vibration Modes ◽  
Electromechanical Properties ◽  
Piezoelectric Transformer ◽  
Voltage Step ◽  
3 Dimensional ◽  
Geometrical Factors ◽  
The Finite Element Model ◽  
Very High ◽  
Good Agreement

The electromechanical properties of a newly proposed 3-dimensional piezoelectric transformer have been investigated. Especially, the effects of 3-dimensional geometry on the maximum tip displacement were carefully investigated. As a result, it was found that the maximum strain of the 3-dimensional piezoelectric device was significantly enhanced up to 4.5 times higher than that of a disk shape device. This data were in good agreement with the finite element model analysis of strains and vibration modes. Moreover, a very high voltage step-up ratio of 290 (10 times higher than the Rosen type), sustaining efficiency more than 96%, were achieved.

The Design of Ultra-Large Hydraulic-Balance Oil Tank With Double-Shell

2011 ◽  
Author(s):  
Guowei Cao ◽  
Zhiping Chen ◽  
Wenjing Guo
Keyword(s):  
Large Scale ◽  
Element Model ◽  
Working Principle ◽  
Oil Tank ◽  
The Difference ◽  
Rational Construction ◽  
Oil Tanks ◽  
The Cost ◽  
The Finite Element Model ◽  
Hydraulic Balance

Large-scale oil tanks are being studied all along because they have a series of advantages. For example, they can reduce the cost of manufacturing and management of the facilities, and save land. So the volume of oil tanks becomes larger and larger during their development. However, without on-site heat treatment, the thickness of the shell of traditional oil tanks is restricted to 200,000 m3. In this paper, a new structure named Ultra-large Hydraulic-Balance oil tank with double-shell was put forward. With the method of hydraulic-balance, oil tanks of this structure could be larger than 200,000 m3. Besides expounding the working principle in detail, a 200,000 m3 oil tank with double-shell was also designed in the paper according to API 650, and the finite element model was used to analyze the stress including intensity and distribution of both shells in order to test and verify its security. Furthermore, its economy was analyzed by comparing with traditional oil tanks. Finally, the problem caused by the difference of liquid lever as well as was discussed. Results show that Ultra-large Hydraulic-Balance oil tank with double-shell owned advantages including rational construction, economy and easy manufacturing.

A Method for Determining the Springing Displacements of Arch Bridges without Technical Data

2011 ◽  
Vol 94-96 ◽  
pp. 375-380
Author(s):  
Xiao Dong Zhang ◽  
Yong Qiang Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Optimization Problem ◽  
Element Model ◽  
Technical Data ◽  
Numerical Examples ◽  
The Difference ◽  
Arch Bridges ◽  
The One ◽  
The Finite Element Model

A method for determining the springing displacements and arch axis of old arch bridges without technical data is presented. By minimizing the difference between the arch axis predicted by the finite element model and the one obtained by assumed arch equation, the optimization problem is formulated and solved. Two numerical examples are given and the results are discussed.

Rebound Analysis for the Diesel Engine Pre-Tightened Bolt Using ABAQUS

2012 ◽  
Vol 189 ◽  
pp. 424-428
Author(s):  
Yu Qing Zheng ◽  
Ya Xian Cheng ◽  
Yu Xia Zheng
Keyword(s):  
Finite Element ◽  
Diesel Engine ◽  
Element Model ◽  
The Other ◽  
Modified Model ◽  
Design Values ◽  
The Difference ◽  
The Finite Element Model ◽  
Test Result ◽  
Real Test

When the nuts are tightened on the big bore diesel engine through the hydraulic tensioner, the preloaded forces imposed on the studs are often less than the design values. In order to get the difference, finite element method was introduced and stress analysis was implemented in Abaqus. Meanwhile the finite element model was modified based on the real test result. Eventually reliable difference results were obtained and the modified model could be applied in the other research.

On the Modeling of an Intervertebral Disc Using a Novel Large Deformation Multi-Shell Approach

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Sébastien Demers ◽  
Abdel-Hakim Bouzid ◽  
Sylvie Nadeau
Keyword(s):  
Finite Element ◽  
Intervertebral Disc ◽  
Finite Element Model ◽  
Large Deformation ◽  
Element Model ◽  
Anulus Fibrosus ◽  
The Difference ◽  
Model Realism ◽  
Contact Pressures ◽  
The Finite Element Model

The objective of this study is to develop an analytical model to predict the stresses and displacements in the lamellae of the intervertebral disc subjected to a compressive force. This is achieved by developing a model based on membrane theory combined to large deformation multishell structural behavior. Equations for longitudinal and circumferential stresses are formulated for each lamella of the anulus fibrosus. Multilamellae interaction is a statically indeterminate problem, which requires equations of compatibility of the displacements of adjacent lamellae to be resolved. The large deformation inherent to soft tissue is considered and the solution is obtained using an iterative process. Elastic interactions with a large deformation is a novelty in analytical modeling of soft tissues. This provides model realism and offers the possibility for new and in-depth investigations. Results are given for longitudinal and circumferential stresses and displacements as well as contact pressures for every lamella of the anulus fibrosus. The analytical results are compared to those of two finite element models. The results suggest that the most highly stressed zone is located on the innermost lamella. Stresses decrease through disc thickness and are at a maximum at the innermost lamella. Circumferential stress is predominant and the difference is less than 5% at any point of the anulus fibrosus when the analytical model is compared to the finite element model using coupled degrees of freedom at the lamellae interface. When compared to the finite element model using contact elements, the difference is below 11%. Contact pressures from the inside to the outside of the anulus fibrosus are shown to decrease nonlinearly. The model presented in this study has demonstrated that it is possible to analytically simulate the complex mechanical behavior of a multishell intervertebral disc subjected to compression, provided some simplifications. Further improvements are suggested to increase model realism and recommendations are given for future experimentation necessary to support both the analytical and numerical models.

Mass and Stiffness Matrices Updating Using the First Modal Data

2016 ◽  
Vol 851 ◽  
pp. 834-839
Author(s):  
Shi Qi Li ◽  
Zhe Zhang ◽  
Shi Ping Liu ◽  
Heng Zhang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Modal Data ◽  
First Order ◽  
Stiffness Matrices ◽  
Real Model ◽  
Engineering Computation ◽  
Practical Engineering ◽  
The Difference ◽  
The Finite Element Model

This paper presents a new direct approach to simultaneously update the analytical mass and stiffness matrices in an undamped model .First, we assume that the difference between the finite element model and the real model is little. Second, only by utilizing the first order modal data orthogonal normalization conditions and eigen equations , we derive the updated matrices. Third, the method can maintain matrices symmetry and sparsity and preserve system connectivity. The merit of the proposed method is simple and accurate in a practical engineering computation. Finally,a numerical example is given to demonstrate the accuracy and effectiveness of the presented updating method.

Arched Vaults Made of Corrugated Sheets: Natural Vibration Frequencies

2019 ◽  
pp. 18-24
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Building Structures ◽  
Friction Forces ◽  
Modeling Process ◽  
The Difference ◽  
Russian Norms ◽  
The Finite Element Model

According to the recent Russian norms, when designing building structures, it is necessary to conduct a dynamic analysis of wind loads, which previously was required not in all cases. In arched vaults of profiled arched self-supporting flooring, it was not always necessary to determine the frequencies and forms of natural vibrations. These parameters can be established using the finite element method. Taking into consideration the complex and lengthy modeling process of arched vaults, in particular the contact areas in regular transverse joints, a large number of finite elements in the models and, as a consequence, considerable time for their calculation, it was necessary to identify a sufficient level of detailing of a finite element model for correct calculations of frequencies and forms of vibrations considered in the operation of structures. The influence of the detailing of the finite element model of arched vaults made of profiled flooring on the determination of their natural frequency is revealed. To substantiate the parameters of the finite element model, it was studied how the results of the calculation was influenced by edge effects, the presence of friction in the joints of corrugations of the profiled flooring, the influence of rubber gaskets in the joints on the work of the arched vault. Much attention is paid to the features of the design scheme associated with the choice of the number of sheets of profiled flooring, taking into account the contact nodes, friction forces, etc. It is established that the first vibration frequency is little dependent on the number of sheets of corrugated flooring and the presence of rubber gaskets in the joints. For subsequent frequencies, the difference can be significant.

Sardinia radio telescope finite element model updating by means of photogrammetric measurements

2015 ◽  
Vol 22 (4) ◽  
pp. 885-901 ◽  
Author(s):  
Flavio Stochino ◽  
Antonio Cazzani ◽  
Sergio Poppi ◽  
Emilio Turco
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Radio Telescope ◽  
Model Updating ◽  
Active Surface ◽  
Element Model ◽  
Actual Surface ◽  
The Difference ◽  
The Finite Element Model ◽  
The Ideal

The 64 m diameter Sardinia Radio Telescope (SRT), located near Cagliari (Italy), is the world’s second largest fully steerable radio telescope with an active surface. Among its peculiarities is the capability of modifying the configuration of the primary mirror surface by means of electromechanical actuators. This capability enables, within a fixed range, balancing of the deformation caused by external loads. In this way, the difference between the ideal shape of the mirror (which maximizes its performance) and the actual surface can be reduced. The control loop of the radio telescope needs a procedure that is able to predict SRT deformation, with the required accuracy, in order to reduce deviation from the ideal shape. To achieve this aim, a finite element model that can accurately predict the displacements of the structure is required. Unfortunately, the finite element model of the SRT, although very refined, does not give completely satisfactory results, since it does not take into account essential pieces of information, for instance, thermal strains and assembly defects. This paper explores a possible update of the finite element model using only the benchmark data available, i.e. the photogrammetric survey developed during the setup of the reflecting surface. This updating leads to a significant reduction in the differences between photogrammetric data and results of the numerical model. The effectiveness of this tuning procedure is then assessed.

Redrawing Operation a Star Shape from Cylindrical Shape Using Experimental and FE Analysis

2020 ◽  
Vol 38 (1A) ◽  
pp. 25-32
Author(s):  
Waleed Kh. Jawad ◽  
Ali T. Ikal
Keyword(s):  
Finite Element ◽  
Effective Strain ◽  
Element Model ◽  
Cylindrical Shape ◽  
Element Analysis ◽  
Punch Force ◽  
Maximum Value ◽  
Element Simulation ◽  
Blank Sheet ◽  
The Finite Element Model

The aim of this paper is to design and fabricate a star die and a cylindrical die to produce a star shape by redrawing the cylindrical shape and comparing it to the conventional method of producing a star cup drawn from the circular blank sheet using experimental (EXP) and finite element simulation (FES). The redrawing and drawing process was done to produce a star cup with the dimension of (41.5 × 34.69mm), and (30 mm). The finite element model is performed via mechanical APDL ANSYS18.0 to modulate the redrawing and drawing operation. The results of finite element analysis were compared with the experimental results and it is found that the maximum punch force (39.12KN) recorded with the production of a star shape drawn from the circular blank sheet when comparing the punch force (32.33 KN) recorded when redrawing the cylindrical shape into a star shape. This is due to the exposure of the cup produced drawn from the blank to the highest tensile stress. The highest value of the effective stress (709MPa) and effective strain (0.751) recorded with the star shape drawn from a circular blank sheet. The maximum value of lamination (8.707%) is recorded at the cup curling (the concave area) with the first method compared to the maximum value of lamination (5.822%) recorded at the cup curling (the concave area) with the second method because of this exposure to the highest concentration of stresses. The best distribution of thickness, strains, and stresses when producing a star shape by

The metachor as a characteristic of the association of electrolytes in aqueous solutions

1984 ◽  
Vol 49 (5) ◽  
pp. 1061-1078 ◽  
Author(s):  
Jiří Čeleda ◽  
Stanislav Škramovský
Keyword(s):  
Aqueous Solutions ◽  
Apparent Volume ◽  
Solutions Of Electrolytes ◽  
Molal Volumes ◽  
The Difference ◽  
High Concentrations ◽  
Experimental Values ◽  
Suitable Characteristic ◽  
Association Of Ions ◽  
Very High

Based on the earlier paper introducing a concept of the apparent parachor of a solute in the solution, we have eliminated in the present work algebraically the effect which is introduced into this quantity by the additivity of the apparent molal volumes. The difference remaining from the apparent parachor after substracting the contribution corresponding to the apparent volume ( for which the present authors suggest the name metachor) was evaluated from the experimental values of the surface tension of aqueous solutions for a set of 1,1-, 1,2- and 2,1-valent electrolytes. This difference showed to be independent of concentration up to the very high values of the order of units mol dm-3 but it was directly proportional to the number of the free charges (with a proportionality factor 5 ± 1 cm3 mol-1 identical for all studied electrolytes). The metachor can be, for this reason, a suitable characteristic for detection of the association of ions and formation of complexes in the solutions of electrolytes, up to high concentrations where other methods are failing.

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