scholarly journals Modal Strain Based Method for Dynamic Design of Plate-Like Structures

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yadong Zhou ◽  
Shaoqing Wu ◽  
Natasa Trisovic ◽  
Qingguo Fei ◽  
Zhiyong Tan
Keyword(s):  
Topology Optimization ◽  
Flat Plate ◽  
Dynamic Properties ◽  
Strain Analysis ◽  
Thin Plates ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Dynamic Design ◽  
Highly Sensitive ◽  
Good Agreement

Design optimization of dynamic properties, for example, modal frequencies, can be of much importance when structures are exposed to the shock and/or vibration environments. A modal strain based method is proposed for fast design of natural frequencies of plate-like structures. The basic theory of modal strains of thin plates is reviewed. The capability of determining the highly sensitive elements by means of modal strain analysis is theoretically demonstrated. Finite element models were constructed in numerical simulations. Firstly, the application of the proposed method is conducted on a central-massed flat plate which was topologically optimized by the Reference. The results of modal strain analysis at the first mode have good agreement with the results from the topology optimization. Furthermore, some features of the strain mode shapes (SMSs) of the flat plate are investigated. Finally, the SMSs are applied to the optimization of a stiffened plate. Attention is focused on the distributions of the SMSs of the stiffeners, which also shows good agreement with the results from the topology optimization in the previous study. Several higher orders of SMSs are extracted, which can visualize the most sensitive elements to the corresponding modal frequency. In summary, both the theory and simulations validate the correctness and convenience of applying SMSs to dynamic design of plate-like structures.

Design and Analysis of Foldable Vehicle using Finite Element Simulation

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
Vikas Radhakrishna Deulgaonkar ◽  
S.N. Belsare ◽  
Naik Shreyas ◽  
Dixit Pratik ◽  
Kulkarni Pranav ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Vehicle Speed ◽  
Element Analysis ◽  
Dynamic Stresses ◽  
Element Simulation ◽  
Vehicle Structure ◽  
Similar Materials ◽  
Good Agreement

Present work deals with evaluation of stress, deflection and dynamic properties of the folded vehicle structure. The folded vehicle in present case is a single seat vehicle intended to carry one person. Design constraints are the folded dimensions of the vehicle and the maximum vehicle speed is limited to 15m/s. Using classical calculations dimensions of the vehicle are devised. Different materials are used for seat, telescopic support and chassis of the foldable vehicle. computer aided model is prepared using CATIA software. Finite element analysis of the foldable vehicle has been carried out to evaluate the static and dynamic stresses induced in the vehicle components. Meshing of the foldable vehicle is carried using Ansys Workbench. From modal analysis six mode shapes of the foldable vehicle are formulated, corresponding frequencies and deflections are devised. Mesh generator is used to mesh the foldable vehicle. The deflection and frequency magnitudes of foldable vehicle evaluated are in good agreement with the experimental results available in literature for similar materials.

scholarly journals Dynamic testing of a modern concrete bridge

1979 ◽  
Vol 6 (3) ◽  
pp. 447-455 ◽  
Author(s):  
J. H. Rainer ◽  
G. Pernica
Keyword(s):  
Natural Frequencies ◽  
Dynamic Testing ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Total Width ◽  
Concrete Bridge ◽  
Reinforced Concrete Bridge ◽  
Natural Modes ◽  
Modes Of Vibration ◽  
Good Agreement

A posttensioned reinforced concrete bridge, slated for demolition, was tested to obtain its dynamic properties. The 10 year old bridge consisted of a continuous flat slab deck of variable thickness having a total width of 103 ft (31.39 m) and spans of 28 ft 6 in. (8.69 m), 71 ft 0 in. (21.64 m), and 42 ft 6 in. (12.95 m). The entire bridge was skewed 10°50′ and the deck was slightly curved in plan.The mode shapes, natural frequencies, and damping ratios for the lowest five natural modes of vibration were determined using sinusoidal forcing functions from an electrohydraulic shaker. These modes, located at 5.7, 6.4, 8.7, 12.0, and 17.4 Hz, were found to be highly dependent on the lateral properties of the bridge deck. Damping ratios were determined from the widths of resonance peaks. The modal properties from the steady state excitation were compared with those obtained from measurements of traffic-induced vibrations and good agreement was found between the two methods.

scholarly journals Dynamic Identification of an Early 20th Century Civil Architectural Building

2020 ◽  
Vol 6 (4) ◽  
pp. 670-678 ◽  
Author(s):  
Bilal Muhammed Bağbancı
Keyword(s):  
Finite Element ◽  
Mechanical Test ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Finite Element Models ◽  
In Situ Tests ◽  
Historical Structures ◽  
Reinforced Concrete Slabs ◽  
Construction Techniques

Historical structures are important in terms of both original construction techniques and cultural heritage. Therefore, material properties, construction techniques and dynamic behaviors of these structures must be identified in order to preserve them in the future by restoration studies.  This study is aimed to serve as an example for similar buildings in the region whose walls were constructed using filled brick with lime mortar and constructed using both timber and reinforced concrete slabs. In this study, the plan layout, construction techniques and the material usage of the building were investigated in detail. The mechanical and dynamic properties such as compressive stress, elastic moduli, shear stress, natural frequencies and mode shapes of the building were determined in-situ by flat-jack, shear and vibration tests. The finite element model of the structure was prepared, and the modal analysis of the structure was performed. The calibration of the model was ensured according to the vibration test results. The results obtained from this study show us that in-situ tests are extremely important for the accuracy of finite element models. It has been determined that the mechanical test data can be used with over 80% success in finite element models.

Prediction Capabilities of Damped Updated Finite Element Models

2011 ◽  
Author(s):  
Vikas Arora
Keyword(s):  
Finite Element ◽  
Model Updating ◽  
Dynamic Properties ◽  
Detailed Comparison ◽  
Element Model ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Complex Frequency ◽  
Structural Modifications ◽  
The Finite Element Model

Model updating techniques are used to correct the finite element model of a structure using experimental data such that the updated model more correctly describes the dynamic properties of the structure. One of the applications of such an updated model is to predict the effects of making modifications to the structure. These modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can’t be used for accurate prediction of complex frequency response functions (FRFs) and complex mode shapes. In this paper, a detailed comparison of prediction capabilities of parameter-based and non parameter-based damped updated methods for structural modifications is done. The suitability of paramter-based and non parameter-based damped updated models for predicting the effects of structural modifications is evaluated by laboratory experiment for the case of an F-shape test structure. It is concluded that parameter-based damped updated models are likely to perform better in predicting the effects of structural modifications.

Forced Vibration Testing and Finite Element Modeling of a Nine-Story Reinforced Concrete Flat Plate-Wall Building

2015 ◽  
Vol 31 (2) ◽  
pp. 1069-1081 ◽  
Author(s):  
Ozan Cem Celik ◽  
Haluk Sucuoğlu ◽  
Ugurhan Akyuz
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Flat Plate ◽  
Forced Vibration ◽  
Structural Model ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Structural System ◽  
Vibration Testing ◽  
Forced Vibration Testing

Tunnel form buildings, owing to their higher construction speed and quality, lower cost, and superior earthquake resistance over that of conventional reinforced concrete buildings, have been widely used for mass housing, urban renewal, and post-earthquake reconstruction projects all over the world as well as in Turkey. However, there have been few dynamic tests performed on existing buildings with this structural system. This study investigates the dynamic structural properties of a typical nine-story reinforced concrete flat plate-wall building by forced vibration testing and develops its three-dimensional (3-D) linear elastic finite element structural model. The finite element model that uses the modulus of elasticity for concrete in ACI 318 predicts the natural vibration periods well. Mode shapes are also in good agreement with the test results. Door and window openings in the shear walls, and the basement with peripheral wall emerge as modeling considerations that have the most significant impact on structural system dynamic properties.

A General Analytical Solution for Free Vibration of Rectangular Plates Resting on Fixed Supports and With Attached Masses

1992 ◽  
Vol 114 (2) ◽  
pp. 239-245 ◽  
Author(s):  
R. K. Singal ◽  
D. J. Gorman
Keyword(s):  
Free Vibration ◽  
Analytical Procedure ◽  
Thin Plates ◽  
Mode Shapes ◽  
Experimental Program ◽  
Space Vehicles ◽  
Superposition Method ◽  
Rectangular Plates ◽  
Solar Panels ◽  
Good Agreement

A comprehensive analytical procedure based on the superposition method is described for establishing the free vibration frequencies and mode shapes of thin plates resting on rigid point supports and with attached masses. Effects of rotary inertia of the attached masses are incorporated into the analysis and are shown to be highly significant. Results of an extensive experimental program are reported and very good agreement is demonstrated between theory and experiment. The analytical procedure has application in numerous contemporary industrial problems, in particular, in the design of solar panels for space vehicles and in the field of electronic packaging.

scholarly journals A Numerical Investigation on Stress Modal Analysis of Composite Laminated Thin Plates

Aerospace ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 63
Author(s):  
Yadong Zhou ◽  
Youchao Sun ◽  
Weili Zeng
Keyword(s):  
Modal Analysis ◽  
Numerical Investigation ◽  
Stress Reduction ◽  
Composite Laminates ◽  
Dynamic Properties ◽  
Stress Component ◽  
High Strength ◽  
Laminated Plates ◽  
Thin Plates ◽  
Mode Shapes

Because of the light weight and high strength, composite laminates have many advantages in aircraft structures; however, they are frequently subjected to severe dynamic loadings during flight. To understand the dynamic properties of composite laminated thin plates at the stress scale, this paper studies the stress modal analysis (SMA) of composite laminated thin plates by finite element method (FEM). Firstly, the basic theory on SMA of composite laminates was given from the classical displacement modal analysis. Secondly, a square laminated thin plate was numerically studied to obtain some distribution laws of the stress mode shapes (SMSs) from the layup and stress component perspectives. Then, based on the characteristics of SMSs in different plies, a modified layup configuration was conducted for possible lower magnitude and more uniform distributions of SMSs. Results indicate that ±45° layups can improve the performance of SMSs of the square plate, without excessively decreasing the modal frequencies. Such fact manifests that ±45° layups are critically vital for the dynamic stress reduction of the square composite laminated plates. Modal participation factor and strain energy were evaluated to assist the determination of critical modes. Lastly, the aspect ratio of the composite plate on layup design was considered. Numerical investigation in this study can serve as a preliminary step of SMSs perspective for the analysis and optimization of dynamic composite laminates.

Tire Vibrations

1977 ◽  
Vol 5 (4) ◽  
pp. 202-225 ◽  
Author(s):  
G. R. Potts ◽  
C. A. Bell ◽  
L. T. Charek ◽  
T. K. Roy
Keyword(s):  
Natural Frequencies ◽  
Standing Waves ◽  
Resonant Mode ◽  
Mode Shapes ◽  
Resonant Vibrations ◽  
Resonant Frequencies ◽  
Radial Tire ◽  
Analysis Techniques ◽  
Thin Ring ◽  
Good Agreement

Abstract Natural frequencies and vibrating motions are determined in terms of the material and geometric properties of a radial tire modeled as a thin ring on an elastic foundation. Experimental checks of resonant frequencies show good agreement. Forced vibration solutions obtained are shown to consist of a superposition of resonant vibrations, each rotating around the tire at a rate depending on the mode number and the tire rotational speed. Theoretical rolling speeds that are upper bounds at which standing waves occur are determined and checked experimentally. Digital Fourier transform, transfer function, and modal analysis techniques used to determine the resonant mode shapes of a radial tire reveal that antiresonances are the primary transmitters of vibration to the tire axle.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

Investigating the vibrational behaviour of a rotating two-blade propeller by using a self-tracking method

2018 ◽  
Vol 233 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Mohammad-Reza Ashory ◽  
Farhad Talebi ◽  
Heydar R Ghadikolaei ◽  
Morad Karimpour
Keyword(s):  
Natural Frequency ◽  
Measurement Errors ◽  
Mode Shapes ◽  
Model Parameters ◽  
Test Results ◽  
Modal Assurance Criterion ◽  
Tracking Method ◽  
Strong Resemblance ◽  
Test Scenarios ◽  
Good Agreement

This study investigated the vibrational behaviour of a rotating two-blade propeller at different rotational speeds by using self-tracking laser Doppler vibrometry. Given that a self-tracking method necessitates the accurate adjustment of test setups to reduce measurement errors, a test table with sufficient rigidity was designed and built to enable the adjustment and repair of test components. The results of the self-tracking test on the rotating propeller indicated an increase in natural frequency and a decrease in the amplitude of normalized mode shapes as rotational speed increases. To assess the test results, a numerical model created in ABAQUS was used. The model parameters were tuned in such a way that the natural frequency and associated mode shapes were in good agreement with those derived using a hammer test on a stationary propeller. The mode shapes obtained from the hammer test and the numerical (ABAQUS) modelling were compared using the modal assurance criterion. The examination indicated a strong resemblance between the hammer test results and the numerical findings. Hence, the model can be employed to determine the other mechanical properties of two-blade propellers in test scenarios.

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