Nonlinear Inverse Perturbation in Structural Dynamics Redesign of Risers

1985 ◽  
Vol 107 (2) ◽  
pp. 256-263 ◽  
Author(s):  
M. M. Bernitsas ◽  
C. J. Hoff ◽  
J. E. Kokarakis
Keyword(s):  
Offshore Structures ◽  
Mode Shapes ◽  
Drilling Mud ◽  
Element Analysis ◽  
Marine Risers ◽  
Geometric Stiffness ◽  
Stiffness Matrices ◽  
The Finite Element Analysis ◽  
Baseline System ◽  
Structural Redesign

Marine risers, and offshore structures in general, may have undesirable natural frequencies and/or mode shapes. Structural redesign is mandatory in such cases. An Inverse Perturbation Redesign (IPR) method, which uses only the finite element analysis of the baseline system and was developed in previous work for general structures, is extended in this work to handle systems with geometric stiffness matrices like marine risers. The IPR method is currently applicable to undamped structural systems or systems with Rayleigh damping and is valid for large or small changes which are frequently required to change modal characteristics of offshore structures. The vibratory characteristics of risers can be altered by modifying among others, the riser top tension, the drilling mud density and the geometry of the riser tubes. The effects of their change on the riser frequencies and modes are derived and applied to two typical riser redesign problems using the IPR method.

Free Vibration Analysis of PZT Glide Heads

1999 ◽  
Vol 121 (4) ◽  
pp. 984-988 ◽  
Author(s):  
Alex Y. Tsay ◽  
Jin-Hui Ouyang ◽  
C.-P. Roger Ku ◽  
I. Y. Shen ◽  
David Kuo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequencies ◽  
Laser Doppler Vibrometer ◽  
Free Vibration Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Bonding Length ◽  
Measured Displacement

This paper studies natural frequencies and mode shapes of a glide head with a piezoelectric transducer (PZT) through calibrated experiments and a finite element analysis. In the experiments, the PZT transducer served as an actuator exciting the glide head from 100 kHz to 1.3 MHz, and a laser Doppler vibrometer (LDV) measured displacement of the glide head at the inner or outer rail. The natural frequencies were measured through PZT impedance and frequency response functions from PZT to LDV. In the finite element analysis, the glide head was meshed by brick elements. The finite element results show that there are two types of vibration modes: slider modes and PZT modes. Only the slider modes are important to glide head applications. Moreover, natural frequencies predicted from the finite element analysis agree well with the experimental results within 5% of error. Finally, the finite element analysis identifies four critical slider dimensions whose tolerance will significantly vary the natural frequencies: PZT bonding length, wing thickness, slider thickness, and air bearing recess depth.

scholarly journals Investigation of Free Vibration Response of E-Glass/Epoxy Delaminated Composite Plates

2012 ◽  
Vol 21 (1) ◽  
pp. 096369351202100 ◽  
Author(s):  
Turan Ercopur ◽  
Binnur Goren Kiral
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Epoxy Composite ◽  
Free Vibration Analysis ◽  
Composite Plates ◽  
Vibration Response ◽  
Mode Shapes ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Free Vibration Response

This paper deals with the finite element analysis of free vibration response of the delaminated composite plates. Free vibration analysis is performed by using ANSYS commercial software developing parametric input files. Natural frequency values and associated mode shapes of E-glass/epoxy composite delaminated plates are determined. Effects of delamination shape, dimension and location on the natural frequency and associated mode shapes are investigated and for the purpose of the observing the effect of the boundary conditions, cantilever and clamped-pinned delaminated composite plates are taken into consideration. Comparisons with the results in literature verify the validity of the developed models in this study. It is observed that the natural frequency decreases in the existence of the delamination and level of the decrease depends on the dimension, shape and location of the delamination.

Vibration Analysis of Radial Drilling Machine Structure Using Finite Element Method

2012 ◽  
Vol 472-475 ◽  
pp. 2717-2721 ◽  
Author(s):  
Rajiv Kumar ◽  
Mohinder Pal Garg ◽  
Rakesh C. Sharma
Keyword(s):  
Machine Tool ◽  
Natural Frequency ◽  
Mode Shapes ◽  
Drilling Machine ◽  
Element Analysis ◽  
Stiffness Matrices ◽  
Machine Tool Structure ◽  
Radial Drilling ◽  
Machine Structure

Manufacturing industries now a days have stringent expectation from the machine tools in terms of productivity as well as quality of products.Vibration plays an important role in determining the quality of product.If the pattern of vibration prevailing in the machine tool during cutting is known,then machine tool structure can be designed in such a way so that natural frequency of machine tool structure can be isolated from the forced frequency.So, this study is focused on finding the natural frequency and mode shapes of radial drilling machine structure.Finite element analysis has been done to find out the natural frequencies and mode shapes of radial drilling machine structure.Assembled mass and stiffness matrices are obtained for each element and solved by using inverse iteration technique.

Modal analysis of 3D needled waste cotton fiber/epoxy composites with experimental and numerical methods

2020 ◽  
pp. 004051752094447 ◽  
Author(s):  
Linlin Lu ◽  
Wei Fan ◽  
Xue Meng ◽  
Tao Liu ◽  
Ling Han ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Epoxy Composites ◽  
Mode Shapes ◽  
Analysis Method ◽  
Fiber Volume ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Waste Cotton Fiber ◽  
Vibration Parameters

The small-size microstructure models of the 3D needled waste cotton fiber/epoxy composites (3DNWCFCs) were brought out to predict their key vibration parameters (natural frequency and mode shapes) with the finite element analysis method. Six kinds of 3DNWCFCs with different parameters were prepared and tested by the experimental modal analysis method to verify the accuracy of the prediction of the natural frequencies and mode shapes with the finite element method. The effects of the fiber volume content and needling density of the composites on the modal behavior were investigated. The natural frequency of the cantilever beams of the composites increased with the increase of the fiber volume content and increased at first then decreased with the increasing needling density. The effect of needling density on the vibration properties of the composite depended on the degree of damage and entanglement of Z-direction fibers. The comparative analysis of the finite element analysis and the experimental results showed that the small-size microstructure models of the 3DNWCFCs were effective to predict their vibration parameters. Therefore, the small-size finite element models can be used to predict the modal properties of the staple fiber reinforced composites effectively with less time and lower economic costs.

Practical Considerations for the Structural Analysis of Offshore Topside Structures Under Gas Explosion Accidents

2012 ◽  
Author(s):  
Dae Suk Han ◽  
Gyusung Kim ◽  
Woo Seung Sim ◽  
Young Sik Jang ◽  
Hyun Soo Shin
Keyword(s):  
Structural Analysis ◽  
Offshore Structures ◽  
Structural Members ◽  
Gas Explosion ◽  
Element Analysis ◽  
Numerical Investigations ◽  
The Finite Element Analysis ◽  
Explosion Accidents ◽  
Blast Loadings ◽  
Dynamic Structural Analysis

Gas explosion accidents have been recognized as a major hazard of offshore facilities in oil & gas industries. Due to the nature of offshore topside structures, even a single collapse of structural members or equipments may lead to enormous economic and environmental losses. Therefore, such potential hazards that cause the accidental collapse need to be evaluated closely. Gas explosion has been categorized as an important issue of the design of offshore structures regarding the severity of the accident. This paper presents practical considerations for the nonlinear dynamic structural analysis of offshore structures under blast loadings from gas explosion accidents. Numerical investigations including modeling of blast loads and idealization of structural materials and members have been conducted for the overall topside structures. As a design step for offshore structures under blast loadings, an applicable guidance on the finite element analysis (FEA) is described in this study.

The Vibration Characteristics of a Large Flexible Vibration Isolation Structure with Finite Element Analysis and Modal Test

2011 ◽  
Vol 199-200 ◽  
pp. 858-864 ◽  
Author(s):  
Liu Bin Zhou ◽  
Tie Jun Yang ◽  
Wan Peng Yuan ◽  
Hui Shi ◽  
Zhi Gang Liu
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Vibration Isolation ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Element Analysis ◽  
Modal Test ◽  
The Finite Element Analysis

A large flexible vibration isolation structure is presented in this thesis, and experimental modal test based on the finite element analysis is carried out in order to find out the vibration characteristics of it. Results show that the natural frequencies and mode shapes calculated by finite element method basically conform to those measured from experimental modal test. Some suggestion to vibration active control in further research is also provided.

Spindle Optimization Design of the Rice Mill Based on ANSYS Workbench

2014 ◽  
Vol 644-650 ◽  
pp. 807-812
Author(s):  
Yan Hua Shi ◽  
Guo Quan Zhang ◽  
Ning Zhang ◽  
Fan Wang ◽  
Zhi Ping Huang
Keyword(s):  
Finite Element ◽  
Optimization Design ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Analysis Model ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Important Field ◽  
Domestic Design ◽  
Ansys Workbench

During the rice mill structural design process, static analysis is an extremely important field, not only decide to what the structure size is, but also for the subsequent fatigue analysis, providing the basis for the overall stability analysis. Now the traditional domestic design mainly based on the empirical design, which is resulted in Performance indicators lag behind of the rice mill, focusing on the performance of vibration is too large and the structure is irrational. Therefore, optimizing the structure of the rice mill to improve the vibration situation has important significance. Using SolidWorks software to build the three-dimensional solid model of the spindle, and then import the model into ANSYS Workbench to establish the finite element analysis model, through the finite element and modal analysis of the results obtained the stress and strain distribution of the natural frequencies and mode shapes characteristic, providing an important basis for further design optimization of the rice mill structure.

scholarly journals Vibration Modes and Parameter Analysis of V-Shaped Electrothermal Microactuators

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Zhuo Zhang ◽  
Yueqing Yu ◽  
Xuping Zhang
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Frequency Equation ◽  
Parameter Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
Shaped Beam ◽  
The Finite Element Analysis ◽  
Parametric Studies ◽  
First Time

Comprehensive analysis on the modal characteristics of V-shaped electrothermal microactuators is presented in this paper for the first time. Considering the unique geometric characteristics of the V-shaped beam, that is, two inclined beams supporting a movable shuttle, both the lateral and longitudinal deflections are taken into account in the modal analysis. Boundary and continuity conditions are employed to obtain the frequency equation. Natural frequencies are then obtained by solving the frequency equation. Mode shapes corresponding to their natural frequencies are also calculated analytically. The theoretical modal analysis is verified with the finite element analysis using ANSYS software. Based on the model analysis, this paper further investigates the relationship between natural frequencies and the volume scaling of the V-shaped beam. Finally, comprehensive parametric studies in terms of material properties and structural dimensions are conducted to provide insights and guidance in designing the V-shaped beam electrothermal microactuators.

The Finite Element Analysis of Vibrating Screen

2011 ◽  
Vol 141 ◽  
pp. 134-138
Author(s):  
Chuan Guang Ding ◽  
Fang Zhen Song ◽  
Bo Song ◽  
Xiu Hua Men
Keyword(s):  
Large Scale ◽  
Natural Frequencies ◽  
Modular Design ◽  
Mode Shapes ◽  
Response Analysis ◽  
Element Analysis ◽  
Harmonic Response ◽  
Vibrating Screen ◽  
The Finite Element Analysis ◽  
Harmonic Response Analysis

The large-scale and modular design of vibrating screen brings about the trend that the screen separate from screen frame. The separation of the screen frame and the screen changes their dynamic characteristics. By making modal analysis and harmonic response analysis in ANSYS, the dynamic data of the screen and the screen frame was obtained, such as the natural frequencies, mode shapes, stress distribution and strain distribution. The results show that the stiffness of screen frame is higher than stiffness of the screen and the side plats and beams of screen are the weak parts.

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