Modal and Thermal Analysis of a Modified Connecting Rod of an Internal Combustion Engine Using Finite Element Method

The connecting rod is one of the most important moving components in an internal combustion engine. The present work determined the possibility of using aluminium alloy 7075 material to design and manufacture a connecting rod for weight optimisation without losing the strength of the connecting rod. It considered modal and thermal analyses to investigate the suitability of the material for connecting rod design. The parameters that were considered under the modal analysis were: total deformation, and natural frequency, while the thermal analysis looked at the temperature distribution, total heat flux and directional heat flux of the four connecting rods made with titanium alloy, grey cast iron, structural steel and aluminium 7075 alloy respectively. The connecting rod was modelled using Autodesk inventor2017 software using the calculated parameters. The steady-state thermal analysis was used to determine the induced heat flux and directional heat flux. The study found that Aluminium 7075 alloy deformed more than the remaining three other materials but has superior qualities in terms of vibrational natural frequency, total heat flux and lightweight compared to structural steel, grey cast iron and titanium alloy.

Finite Element Modeling and Modal Analysis of Complicated Structure with Bolted Joints

A contact bolt model is proposed as a new modeling technique to investigate the complex structure with bolted joints for modal analysis and compared with the coupled bolt model, and the test results are given. Among these models, the coupled bolt model provides the best accurate responses compared with the experimental results. The contact bolt model shows the best effectiveness and usefulness in view of operational time. The bolt models proposed in this study are adopted for a dynamic characteristic analysis of a large diesel engine consisting of several parts which are connected by many bolts. The dynamic behavior of the entire engine structure was investigated by experiment. The coupled bolt model and the contact bolt model were applied to model the assembly of engine with high preload. The experimental results are in good agreement with the finite element method （FEM） results. Compared with the other models, the contact bolt model presented in this paper is more effective and useful in view of operational time and experience of analysts.

Firmness evaluation of melon using its vibration characteristic and finite element analysis

The “Huang gua” melons were measured for their physical properties including firmness and static elastic modulus. The vibrational characteristics of fruits and vegetables are governed by their elastic modulus (firmness), mass, and geometry. Therefore, it is possible to evaluate firmness of fruits and vegetables based on their vibrational characteristics. Analysis of the vibration responses of a fruit is suggested for measuring elastic properties (Firmness) non-destructively. The impulse response method is often used to measure firmness of fruits. The fruit was excited using three types of balls (wooden, steel and rubber) and the vibration is detected by an accelerometer. The Instron device was used to measure the static elastic modulus of the inner, middle and outer portions of melon flesh. Finite element (FE) technique was used to determine the optimum excitation location of the chosen measurement sensor and to analyze the mode shape fruits. Four types of mode shapes (torsional or flexural mode shape, first-type, second-type spherical mode and breathing mode shape) were found. Finite element simulation results agreed well with experimental results. Correlation between the firmness and resonant frequency (r2=0.91) and between the resonant frequency and stiffness factor (r2=0.74) existed. The optimum location and suitable direction for excitation and response measurement on the fruit were suggested.

Structural optimization of precision instruments through modal analysis

In order to improve the dynamic stability of precision instruments during the design process, a compositive design method based on modal analysis of structure is proposed. With uniform boundary conditions and material characters, the results of Finite Element Analysis (FEA) vary with models. It should be checked whether the model is correctly simplified. Modal experiments can be used for such purpose. The method combines the high efficiency and agility of FEA with the reliability and accuracy of experiments, and avoids the drawbacks of FEA or experiments, such as uncertainty of FEA and high cost of experiments. Taking rotor frame structure as an example, this method is applied as follows: First the modal characters of structure are analyzed with FEA, and then the natural frequencies of the structure are tested by experiments to check the reliability of FEA method, and finally the design scheme is optimized by modifying structure parameters with confirmed FEA.

MODAL ANALYSIS OF A CHASSIS FRAME OF A HEAVY LECTRA HAUL

The chassis frame of a heavy lectra haul is analysed by both modal experiment method and finite element method (FEM ) . The first ten order modal parameters of the chassis frame have been obtained satisfactorily. These parameters have important reference value in designing the chassis frame properly and provide a necessary basis for the fault diagnostics of the truck.

Finite element analysis of dynamic response and structure borne noise of gearbox

A dynamic finite element method combined with finite element mixed formula for contact problem is used to analyze the dynamic characteristics of gear system. Considering the stiffness excitation, error excitation and meshing shock excitation, the dynamic finite element model is established for the entire gear system which includes gears, shafts, bearings and gearbox housing. By the software of I-DEAS, the natural frequency, normal mode, dynamic time-domain response, frequency-domain response and one-third octave velocity grade structure borne noise of gear system are studied by the method of theoretical modal analysis and dynamic response analysis. The maximum values of vibration and structure borne noise are occurred at the mesh frequency of output grade gearing.

Modal analysis of the torque converter in different prestress

In order to study the mechanical properties and the dynamic performance of torque converter,to reduce the vibration and noise during the operation and to improve the stability,a 215 mm hydraulic torque converter is taken as the research object,and modal analyses are performed based on the finite element method.The weak parts of the impeller structure are obtained after calculating the models of the impeller and turbine without prestress.The variation of the modal frequency of the turbine and impeller are obtained under different prestress conditions by calculating different rotational speeds of the transmission shaft.The fundamental frequencies of the impeller and the turbine increase by 0.43%and 4.82%respectively when the rotational speed ranges from 100 rpm to 4500 rpm.The results of the present research indicate that the modal frequencies at different speeds are similar to the fundamental frequencies of the structure.Therefore,it is possible to estimate the vibration characteristics of the structure and optimize the structural design by numerical modal analysis in the static state instead of the dynamic state.

Finite Element Analysis and Test of an Ultrasonic Compound Horn

An?ultrasonic compound horn is designed and manufactured, and the horn is analyzed by wave equation, finite element method and test. The modal frequencies and frequencies of the first and second longitudinal vibration of the horn are obtained by the finite element analysis. The horn is made and modal testing is carried out. The modal frequencies of the first and second longitudinal vibration are obtained respectively. The test results are in good agreement with the theoretical calculation. Experimental results show the maximum amplitude of the horn can reach 9?nm with applied excitation voltage of amplitude 7?V and frequency 21,450?Hz, when the amplitude of voltage increases?to 80?V, the horn of maximum amplitude reaches?23 μm. The maximum amplitude of the horn is approximately proportional to the amplitude of excitation voltage. The horn has the characteristics of high sensitivity and large amplitude, and can be used in ultrasonic machining and other fields.

Dynamic analysis and modal test of long-span cable-stayed bridge based on ambient excitation

To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the girder with double ribs. Based on the simplified model four stiffness formulae were deduced according to Hamilton principle. These formulae reflect well the contribution of the flexural, shearing, free torsion and restricted torsion deformation, respectively. An identification method about modal parameters was put forward by combining method of peak value and power spectral density according to modal test under ambient excitation. The dynamic finite element method analysis and modal test were carried out in a long-span concrete cable-stayed bridge. The results show that the errors of frequencies between theoretical analysis and test results are less than 10% mostly, and the most important modal parameters for cable-stayed bridge are determined to be the longitudinal floating mode, the first vertical flexural mode and the first torsional mode, which demonstrate that the method of stiffness distribution for three beams model is accurate and method to identify modal parameters is effective under ambient excitation modal test.

Dynamic Characteristics of Inflated Torus Using Finite Element Analysis

In recent years, inflatable structures have been a subject of interest for space applications such as communication antenna, solar thermal propulsion and entry/landing systems. The inflatable structures characterized by high strength-to-mass ratios, minimal stowage volume, which makes them suitable for cost-effective large space structures. A typical example for the inflatable structure is the inflated torus which often used in order to provide structure support. In this study, our main focus is to understand the dynamic characteristics of an inflated torus in order to formulate an accurate mathematical model suitable for active vibration control applications. A commercial finite element package, ANSYS, is used to model the inflated torus. To verify the model the obtained frequencies and mode shapes are compared with the published results, which are derived using analytical approach, the verification shows a good agreement between the FEM and the analytical results. Based on the verified model, parametric study was investigated; the material thickness increase causes the natural frequencies decrease, while the increase of the inflation pressure simply results in stiffening the ring, which means that the natural frequency increased. The FEM analysis gives an easy and fast way for the vibration analysis of the structures compared with the complicated analytical solutions.

THE MODAL SYNTHESIS IN THE ANALYSISOF ROBOT KINETO-ELASTODYNAMICS

ＴＨＥＭＯＤＡＬＳＹＮＴＨＥＳＩＳＩＮＴＨＥＡＮＡＬＹＳＩＳＯＦＲＯＢＯＴＫＩＮＥＴＯ－ＥＬＡＳＴＯＤＹＮＡＭＩＣＳＪｉａｎｇＪｉａｎｈｏｎｓ（姜剑虹）（ＮａｎｊｉｎｇＥｎｇｉｎｅｅｒｉｎｇＩｎｓｔｉｔｕｔｅｏｆＥｎｇｉｎｅｅｒｉｎｇＣｏｒｐｓ）ＴＨ...

Modal Correlation Based Analysis on Dynamic Characters of a Commercial Semi-Trailer's Chassis Frames

In order to evaluate two different schemes＇ structural dynamic characters, dynamic response analysis of a commercial truck＇s main chassis frames is carried out. On the basis of correlation study between the tested and calculated modal results, the assembled frames＇ finite element analysis （FEA） models with sufficient precision are built up. Random response analysis in frequency domain is carried out with these FEA models, RMS values of yon Mises and main principle stresses of these two frames are obtained. It shows that the analysis resuits of the distributing tendency and concrete value ranges are coincident very well with test results. And from the results, it could be concluded that frames of scheme A endures relative better loading conditions and should be adopted as the final scheme.

Finite Element Analysis of the 2 m Telescope Assemble

To improve the performance of the 2 m telescope, the optimum design is applied to the telescope assemble. Referring to the telescope assemble with the dimetric truss, a group of reasonable sizes of the telescope assemble are found by optimization methods and modal analysis, which will raise the resonant frequency by 4.21 %. As a result, the telescope assemble is less likely to resonate. Besides, the dynamic response module in ANSYS is utilized to analyze the modal type, harmonic vibration response and random vibration response of the telescope assemble. By the calculation of ANSYS, finite dement analysis （FEA） method proves that the performance of the telescope assemble is mildly enhanced by means of optimum design.

Finite Element Analysis on Vibration Characteristics of an Offshore Floating Breakwater

The construction of seaside facilities is a hot topic in the field of ocean engineering.In this paper,a new type of floating breakwater is designed by 3D-CAD geometric modeling.Based on the vibration theory and finite element tech-nology,the floating breakwater model is optimized,and the modal analysis of the structure with the bracket as main body and blades as functional attachments is carried out.Natural frequencies and mode shapes of the blades are fi rst calculated,and the effects of the natural frequencies in both dry and wet conditions are taken into account.Modal analysis and harmonic response analysis of the bracket with different lengths by removing the blades are also carried out,and the different var-iations of the natural frequencies between several bracket units are compared.The responses of the key position of the bracket under different loads and different bracket lengths are analyzed.The influence of liquid on the natural frequency of the blades and the influence of the length of the bracket on the natural fre-quency of the bracket are discussed in the fluid-solid coupling state.Research in this paper provides a data basis for the safety assessment of the breakwater construction.

Fatigue Strength and Modal Analysis of Bogie Frame for DMUs Exported to Tunisia

The equivalent stress at key positions of Bogie Frame for DMUs Exported to Tunisia is obtained by using simulation analysis. The evaluation of static strength and fatigue strength is checked referring to UIC specification and Goodman sketch for welding materials. In addition, the modal analysis of the frame is made, and the vibrational modal of frame in given frequency domain is predetermined to evaluate the dynamical behavior of the frame in order to meet the dynamical design requirements. The results show that the key points of the calculated frame of the equivalent stress are less than allowable stress, and thus it could provide a theoretical foundation for the optimized design of frame structure and safety of industrial production.

Modal Analysis of Drilling Machine Derrick

In this paper, the finite element analysis software (ANSYS) is applied to the modal analysis of a ZJ30/1700CZ's drilling machine derrick under a natural condition and a loaded condition, respectively. The preceding nine step natural frequencies and the corresponding mode shapes of the derrick are calculated. By means of the comparison of the natural frequency of the derrick with the design work frequency of the drilling machine and the analysis of the step mode shape of the derrick, the drilling machine derrick structure design is proved to be correct.

Modal-FEM混合法对复杂终端进气道RCS的计算

对带有复杂结构终端进气道的电磁散射问题进行了研究。给出一种高效的Modal-FEM分析方法,采用改进的模式法处理前端空腔部分,而复杂终端则只需有限元法进行一次求解;最后,在分界面上耦合得到整体的散射结果。与其他数值算法相比,计算结果表明:混合算法在保证精度的前提下减少了计算时间和所需内存,为计算带复杂终端进气道的RCS找到了一条可行的路径。

Stress and modal birefringence of single-mode specialty optical fibers with three-stress regions

Stress-induced birefringence and modal birefringence of single-mode specialty optical fibers with three stress regions are numerically analyzed by the vector finite element method. Stress distribution and stress-induced birefringence distribution of three kinds of optical fibers with different cross structures are presented and compared, and the influence on the stress- induced birefringence by temperature change are analyzed as well. The results show that the fibers with three-stress regions have a lower linear birefringence, which is very important for the fabrication of the circular polaxization-maintalning fiber with high performance drawn from the same fiber preform by using the spinning method.

Influence of structure and material on the vibration modal characteristics of novel combined flexible road wheel

Aiming at the independent development of tracked vehicles,it is urgent to improve its mobility,passability and ride comfort,a new type of flexible road wheel with a“wheel-hinge-hub”combined structure is proposed in this study.The vibration model characteristics of the flexible road wheel were studied by the combination of numerical simulation and experiments.The superelasticity of rubber is obtained through uniaxial tensile experiment of the material and a detail three-dimensional nolinear finite element model of the flexible road wheel is established through finite element software ABAQUS.The free vibration equation of the flexible road wheel is solved by Lanczos vector direct superposition method,and its predicted modes and natural frequencies are compared with experimental results,which verifies the accuracy and reliability of the established finite element model.On this basis,the effects of various key structural or material factors on the natural frequencies of the flexible road wheel are studied using orthogonal experimental design method.Besides,the vibration modal characteristics of the flexible road wheel are also compared with those of the rigid road wheel.The research results provide a theoretical basis for the vibration and noise reduction of flexible road wheel.

Analysis of sp Pillar Stability Experiment: Continuous thermo-mechanical model development and calibration

The paper describes an analysis of thermo-mechanical （TM） processes appearing during the Aspo Pillar Stability Experiment （APSE）. This analysis is based on finite elements with elasticity, plasticity and dam- age mechanics models of rock behaviour and some least squares calibration techniques. The main aim is to examine the capability of continuous mechanics models to predict brittle damage behaviour of gran- ite rocks. The performed simulations use an in-house finite element software GEM and self-developed experimental continuum damage MATLAB code. The main contributions are twofold. First, it is an inverse analysis, which is used for （1） verification of an initial stress measurement by back analysis of conver- gence measurement during construction of the access tunnel and （2） identification of heat transfer rock mass properties by an inverse method based on the known heat sources and temperature measurements. Second, three different hierarchically built models are used to estimate the pillar damage zones, i.e. elas- tic model with Drucker-Prager strength criterion, elasto-plastic model with the same yield limit and a combination of elasto-plasticity with continuum damage mechanics. The damage mechanics model is also used to simulate uniaxial and triaxial compressive strength tests on the ,Aspo granite.