Results Of Finite Element Modal Analysis Research Articles

Integrating a Physical Model with Multi-Objective Optimization for the Design of Optical Angle Nano-Positioning Mechanism

In light of recent advancements in synchrotron radiation technology and nano-technology, there has been a marked increase in the need for ultra-precision nano-positioning mechanisms. This paper presents a method that integrates physical models with multi-objective optimization for developing an optical angle nano-positioning mechanism. We begin by examining the actual motion law of the mechanism, based on kinematic principles. The outcomes from this kinematic analysis facilitate a static analysis of the flexible hinge, identified as a critical component of the mechanism. Subsequently, we establish a dynamic model for the entire mechanism. By employing the physical model as a base and combining it with the optimization algorithm, we identify the optimal design parameters for the mechanism. The design achieves a resolution of 50 nrad and meets the specified requirements. The first-order inherent frequency of the mechanism is approximately 43.75 Hz. There is a discrepancy of 2.63% from the finite element modal analysis results and a 3.33% difference from the theoretical analysis results, validating the reliability of the design method proposed in this study.

Dynamic Characteristics Analysis of a Rigid Body System with Spatial Multi-Point Supports

This paper presents the dynamic characteristics analysis of a rigid body system with spatial multi-point elastic supports, as well as the sensitivity analysis of support parameters. A rigid object is characterized by six degrees-of-freedom (DOFs) motions and considering the spatial location vector decomposition of elastic supports, a rigid body system dynamic model with spatial multi-point elastic supports is derived via the Lagrangian energy method. The system modal frequencies are calculated, and to be verified by finite element modal analysis results. Next, based on the above-mentioned model, system modal frequencies are obtained under different support locations, where the support stiffness components are different. Interpolate the stiffness components corresponding to each support location, calculate system modal frequencies, and the response surface model (RSM) for system modal frequencies is established. Further, based on the RSM modal analysis results, the allowable support location for the system modal insensitive area can be obtained. At last, a lubricating oil-tank system with four supports is taken as an example, and the effects of support spatial locations and stiffness components on the system inherent characteristics are discussed. This present work can provide a basis for the dynamic design of the spatial location and stiffness for this type of installation structures.

Reinforcement and Restoration Studies of the Edremit Ataturk House

Edremit Ataturk House has been restored under international restoration principles. Due to its importance, a systematic study was carried out to prevent the building from suffering damage. The current situation of the building was investigated by using slightly destructive and non-destructive test methods. Flat-jack and shear tests were used in order to identify the mechanical properties of masonry walls according to the ASTM standards. The operational modal analysis test method was used in order to understand its dynamic characteristics. After the diagnosis phase, a finite element model was prepared and calibrated according to the in-situ test results. The reinforcement studies were performed according to the finite element modal analysis results. Finally, the differences between the dynamic properties of the structure were evaluated by vibration tests before and after the restoration works.

Method of achievement the high accuracy of the shape of reflectors of mirror antennas of spacecraft

Analysis of conditions, which are required for mirror antennas of spacecrafts destined for transmission of high-frequent radio signals, is done in this paper. These conditions are regarded to resistance and rigidity of the construction features of the material of an antenna’s reflector and its surface’s quality. It is mentioned that the requirements to the accuracy of the reflector’s shape grow together with the frequency of a radio signal. Altogether, the existing constructions of antennas and the producing technologies are not capable to obtain those requirements. The innovative method of controlling the shape of a reflector of a mirror antenna is presented in the paper. Its application gives an opportunity to produce constructions with a highly accurate surface. This method deals with the fact that the required accuracy of a reflector can be achieved via elastic deformation of its shell. Design of the regulating units for different types of reflectors is developed. We propose an algorithm of choosing the number of the regulating units and their locations. This algorithm uses the results of finite-element modal analysis of a reflector’s shell. Innovative design of axisymmetric and offset reflectors which shell’s shape can arise from controlled deformation is developed. We also suggest the design of the reflector’s shell with a timber with regulating units on it. Such design provides an opportunity to significantly decrease the number of the regulating units. Project of the reflector with a timber and console rods possessing low mass and high stiffness is developed. Method of achievement the high accuracy of a reflector, presented in the paper, can be applied to design of new space antennas operating in high-frequency interval.

Free Modal Analysis for Spiral Bevel Gear Wheel Based on the Lanczos Method

In order to obtain the spiral bevel gear wheel natural frequencies and mode shapes in the unconstrained state for the purpose of dynamic characteristics study, the spiral bevel gear wheel three-dimensional solid model of a mini-bus main reducer is established in this paper. The finite element model of spiral bevel gear wheel which consists of 32351 nodes, 18436 solid187 tetrahedrons finite element method elements is established by using free grid meshing method in this paper. Extract the first 6 orders modals parameters such as natural frequencies and main vibration mode shapes by using the Lanczos method. The new 1st to 4th orders modals are formed by comparing and merging 2 orders repeated modals. In order to verify the effectiveness of the finite element analysis results, the experiment modal test based on the impulse force hammer percussion transient single-point excitation and multi-point response analysis method has been done. The maximum difference value of natural frequency between experimental modal test result and finite element modal analysis results is 29.86 Hz, the maximum error rate is 0.41%, which confirmed the result of finite element method is effective and reliable. The conclusions reflect the vibration response characteristics of spiral bevel gear wheel, and provide theoretical basis for dynamic response, structure design and optimization of spiral bevel gear wheel.

Design, fabrication and testing of composite sandwich integral structure of spacecraft antenna

An innovative design of the space offset mirror antenna made of composite material is presented in the paper. The antenna body is designed in the form of a composite sandwich conical shell with a cutout made on the side surface. The body geometry is selected to conform to and accommodate the signal transmitting zone. The antenna reflector is located at the bottom part of the sandwich cone and the feed is placed at the top creating a compact antenna configuration. A full-size prototype of the antenna has been designed, built and tested. Design parameters of the sandwich structure have been determined based on the results of finite-element modal analysis. The experimental results of vibration and thermal cycling testing of the prototype provide a proof of concept and evidence of the design feasibility. It is shown that the stiffness characteristics of the proposed integral sandwich antenna ensure efficient applications of such composite structures in the space antennas designed for various ranges of radio wave transmission.

Evaluation on bridge dynamic properties and VIV performance based on wind tunnel test and field measurement

Full scale measurement on the structural dynamic characteristics and Vortex-induced Vibrations (VIV) of a long-span suspension bridge with a central span of 1650 m were conducted. Different Finite Element (FE) modeling principles for the separated twin-box girder were compared and evaluated with the field vibration test results, and the double-spine model was determined to be the best simulation model, but certain modification still needs to be made which will affect the basic modeling parameters and the dynamic response prediction values of corresponding wind tunnel tests. Based on the FE modal analysis results, small-scaled and large-scaled sectional model tests were both carried out to investigate the VIV responses, and probable Reynolds Number effects or scale effect on VIV responses were presented. Based on the observed VIV modes in the field measurement, the VIV results obtained from sectional model tests were converted into those of the three-dimensional (3D) full-scale bridge and subsequently compared with field measurement results. It is indicated that the large-scaled sectional model test can probably provide a reasonable and effective prediction on VIV response.

The Vibration Characteristics Analysis of U-Shaped Pipe Based on Finite Element and Modal Experiment

The U-shaped pipe located in the compressor piping system of the lyophilizer is studied in this paper. Its finite element modal analysis is carried out through the software ABAQUS, and at the same time, the experimental modal analysis is conducted by the software LMS Test.lab and its corollary equipment. Through the comparison between the finite element modal analysis results and the experimental modal results, it can be seen that the two results have good consistence, which verifies that the finite element model is reasonable. This paper provides reference for the further studies of the curving pipe vibration.

Dynamic Characteristic Analysis and Structural Modification of a 5-Axis Horizontal Machining Center Considering Joint Surface

In order to make a 5-axis linkage horizontal machining center have better dynamic characteristics, considering the influence of joint surface, dynamic characteristic analysis is conducted to the machining tool. Based on finite element modal analysis results, the weak link is found and optimized. Through the finite element calculation and analysis, the structure rigidity obviously raises after optimization. This offers a new idea on how to improve the rigidity of complete machine of machining tool for later research.

Improving screw compressor housing design using simulation.

The sound radiation from a rotary screw compressor was simulated using structural finite element and acoustic boundary element analysis. The modes of the housing were measured with and without the screws. Finite element modal analysis results were compared to the experimental modes with good agreement. Results demonstrated that the screws affected the bending modes but not the more important cylinder modes of the compressor housing. The sound radiation from the compressor housing was then predicted using acoustic boundary element analysis. The results indicated that the second and fourth pumping frequencies were close to two structural modes. Subsequent simulations investigated the effect of design changes on the housing. These changes included using a thicker cylinder and adding ribs.

Evaluation of Test/Analysis Correlation Methods for Crash Applications

A project has been initiated to improve crash test and analysis correlation. The work in this paper concentrated on the test and simulation results for a fuselage section. Two drop tests of the section were conducted. The first test was designed to excite the linear structural response for comparison with finite element modal analysis results. The second test was designed to provide data for correlation with crash simulation. An MSC.Dytran model was developed to generate nonlinear transient dynamic results. Following minor modifications, the same model was executed in MSC.Nastran to generate modal analysis results. The results presented in this paper concentrate on evaluation of correlation methodologies for crash test data and finite element simulation results.

EXPERIMENTAL. MODAL. ANALYSIS OF REINFORCED CONCRETE STRUCTURES

Summary Experimental modal analysis techniques have been shown to be applicable to both laboratory test specimens and in situ test structures made of reinforced concrete. These techniques, in general, apply only to linear structures; however, many concrete structures are designed to remain in the linear, uncracked response region during dynamic excitation (nuclear power plant structures, for example). Data from the experimental analyses agreed well with finite-element modal analysis results, and the numerical models were further refined based on the experimental results. Because of the relatively low excitation levels required, these methods provide engineers with techniques for assessing the as-built condition of a structure without introducing damage into the structure. If a concrete structure is damaged, the experimental modal analysis methods could possibly be used to monitor its deterioration. Further investigations are needed to evaluate the sensitivity to damage of the experimentally determined modal properties. Also, methods must be found to determine, without prior modal data, if an in-situ structure is in a damaged state. These topics are being pursued by other researchers in the experimental modal analysis field.6 In its current form, experimental modal analysis methods can provide both practicing and research engineers with a valuable tool for verifying dynamic properties of reinforced concrete structures.