Different Modes Of Vibration Research Articles

Study for the Identification of Dominant Frequencies and Sensitive Structure on Machine Tools Using Modal Decoupling and Structural Sensitivity Analysis

The research on machine tool vibration has significant impact to improve the processing quality of the processed parts. The vibration response on the surface quality is quite different based on different modes of vibration. Current study proposed a new approach of modes decoupling based on Operational Deflection Shape (ODS) and structural sensitivity analysis, which used to identify the structural vibrations on surface topography in manufacturing process. Method According to the modes decoupling based on the ODS method, the dominant vibration frequencies of machine tool are identified in a wide range of frequency band. Furthermore, the modal mass distribution matrix analysis is used to determine the sensitive structures that cause greater machining errors. A milling process is used to conduct experiments. The experimental and theoretical results indicate that (i) the contribution of dominant vibration frequency to the vibration of machine tool is larger than weak modes vibration and (ii) the sensitive structure has higher vibration energy than the insensitive structures. The multimode vibration at dominant frequencies of the sensitive structures (MVDFSS) directly can determine the surface topography of the products.

Damping Measurements on a Multi-Blade Cascade with Multiple Degrees of Freedom: A Francis-99 Test Case

Due to thinner blades and higher demands for flexibility, the high-head Francis runners designed today face considerable challenges that severely affect the runners’ expected lifetime. For many high-head Francis runners, the leading cause of fatigue is blade cracking due to Rotor-Stator Interaction, which cause vibrations in the runner blades.Accurate prediction of the vibration magnitudes in a turbine is paramount in designing a reliable Francis runner. The understanding of the interaction between the hydrodynamic forces and the internal stresses in the runner is not yet sufficient to make this prediction. Previous investigations have identified some key parameters that affect dynamic behaviour in water, such as added mass, as well as added stiffness and damping from moving water. These parameters affect the natural frequency and damping of a structure, which in the end will affect what vibrations magnitudes the runner will be subjected to for a given frequency of excitation. The behavior of these parameters have recently been investigated by several researchers, but the effect of neighboring blades is yet not understood.A multi-blade cascade has been tested for four of its different modes of vibration. The results indicate that the slope of the damping with respect to the inverse Strouhal number is constant. This slope was found to be the same as for several single-blade tested performed, both in the same rig and in other works. The implication is that the product of added mass and mode shape does not change significantly.

Vibration, Buckling and Deflection Analysis of Cracked Thin Magneto Electro Elastic Plate Under Thermal Environment

The Magneto-Electro-Elastic (MEE) material exhibits pyroelectric and pyromagnetic effects under thermal environment. The effects of such pyroelectric and pyromagnetic behavior on vibration, buckling and deflection analysis of partially cracked thin MEE plate is presented and discussed in this paper. The aim of the study is to develop an analytical model for the vibration and geometrically linear thermal buckling analysis of cracked MEE plate based on the classical plate theory (CPT). The line spring model (LSM) is modified for the crack terms to accommodate the effect of electric and magnetic field rigidities, whereas the effect of thermal environment is accommodated in the form of thermal moment and in-plane forces. A classical relation for thermal buckling phenomenon of cracked MEE plate is also proposed. The governing equation for cracked MEE plate has also been solved to get central deflection which shows an important phenomenon of shift in primary resonance due to crack and temperature rise. The results evaluated for natural frequencies as affected by crack length, plate aspect ratio and critical buckling temperature are presented for first four modes of vibration. The obtained results reveal that the fundamental frequency of the cracked plate decreases with increase in temperature and crack length. Furthermore the variation of the critical buckling temperature with plate aspect ratio and crack length is also established for different modes of vibration.

Synthesis, growth, structural, thermal and optical properties of diguanidinum hydrogen phosphate monohydrate (G2HP) crystal for NLO applications

A semi-organic nonlinear optical diguanidinum hydrogen phosphate monohydrate (G2HP) single crystal was synthesized by slow solvent evaporation technique. Single crystal XRD analysis was done on the grown semi-organic crystal G2HP. It reveals that the title compound has crystallized in a non-centrosymmetric tetragonal system with space group \({\text{P}}\bar{4}2_{1} {\text{c}}\). Solubility of the synthesized material has been determined for various temperatures using water as solvent. Intermolecular interaction of diguanidinum G2HP was visualized using Hirshfeld surface (HS) analysis. HS analysis permitted for the identification of individual types of intermolecular and their impact on the complete packing. Fingerprint plots of HS were used to locate and analyze the percentage of H…H, O…H, N…H hydrogen-bonding interactions. The functional groups present in diguanidinum G2HP and the different modes of vibrations were identified by Fourier transmission spectrum analysis. The UV–Visible spectrum (UV–Vis) of G2HP crystal was between 200 and 800 nm and the lower cut off wavelength was found to be 242 nm. The energy band gap was estimated as 5.5 eV using Tauc’s plot. The thermogravimetric and differential thermal analysis ensures the thermal stability, melting point and decomposition point of the crystal. From the thermal study, the material is found to be stable up to 397 °C. Second harmonic generation studies shows that G2HP crystal exhibits 0.5% efficiency in comparison with other standard materials.

Analysis of the global second-order effects on irregular reinforced concrete structures using the natural period of vibration

Abstract The χT parameter, a simplified method recently presented, allows to estimate the global second-order effects on reinforced concrete frames using the natural period of vibration. This parameter was developed based on the fact that both natural period of vibration and global second-order effects depend essentially on the stiffness and mass matrices of the structure, being thus related. In this paper, numerical analyses are conducted on nine models with different patterns of irregularity in terms of geometry in plan and stiffness. The main purpose of these analyses is to evaluate the applicability of the χT parameter in asymmetric structures as well as that can present torsional modes as the fundamental mode of vibration. In addition, different hypotheses are tested in order to verify the influence of the different modes of vibration in the structural sensitivity to global second-order effects. Results of the simplified analyses were compared to the final bending moment values obtained through a nonlinear numerical analysis considering the P-Δ effect. It is observed that the parameter χT is a promising indicator for a simplified estimation of the global second-order effects for concrete frames, especially when higher modes of vibration are taken account in the analysis.

Vibrational characterization of wavy atomic structures of single walled boron nitride nanotubes

This paper illustrates the variation in the natural frequencies of different modes of vibration considering the different types of waviness of the atomic structures of single walled boron nitride nanotubes (SWBNNTs), i.e., sinusoidal, elliptical and parabolic. The waviness present in the atomic structures of SWBNNTs causes a variation in the localized stiffness in waviness regions, thereby affecting the natural frequency of the SWBNNTs. Thus, it is important to understand the effects of the different types of possible waviness present in the atomic structures of SWBNNTs on their natural frequency. A vibrational analysis was performed for the bridged configuration (with both ends fixed) of SWBNNTs. Continuum modelling based analytical and finite element method (FEM) simulation approaches were used to estimate the natural frequencies of SWBNNTs with different types of wavy curvatures. The FEM approach reflects the shear deformation on the natural frequency of wavy nanotubes, whereas inclusion of shear deformation in the analytical approach adds complexity to the model, which requires more computational time for analysis. The obtained results indicate that the sinusoidal curvature of wavy atomic structures of SWBNNTs is more sensitive compared to the parabolic and elliptical curvatures of wavy nanotubes. Mode shape analysis is also found to be useful for estimating the type of curvature in the atomic structures of the nanotube. As presented herein, understanding the effect of waviness on the variation in the natural frequency of the wavy atomic structure of SWBNNTs is found to be useful for the practical realization of wavy atomic structure based nano-mechanical resonators for applications such as in sensor systems on the nano-scale level.

Crystal growth and investigation of novel semi organic single crystal: l-malic acid sodium nitrate for photonic applications

l-Malic acid sodium nitrate, a novel semi organic nonlinear optical crystal was grown from aqueous solution by slow evaporation method at room temperature. The cell parameters for the grown crystal were determined by using single crystal X-ray diffraction method. The different functional groups with different modes of vibrations were confirmed by FTIR spectral analysis. The optical absorption studies show that the crystal has wide optical transparency in the entire visible region. From UV absorption profile, the electronic optical band gap and Urbach energy is calculated as 5.0 eV and 0.1401 eV. The photoluminescence spectra exhibit different peaks to indicate the single transitional band structure and high purity of the grown crystal. The EDAX and SEM study shows the presence of elements in the grown crystal and growth of second layer over the surface. The second harmonic generation efficiency was confirmed by the Kurtz powder method using Nd:YAG laser with fundamental wavelength of 1064 nm. DSC study shows that the grown crystal was thermally stable up to 273 °C. The dielectric behavior of the grown crystal was measured in the frequency range 50 Hz–5 MHz at different temperatures. The Vickers micro hardness studies were carried out on the grown crystals and there by Vickers hardness number (Hv) and work hardening coefficient (n) were calculated.

On estimation of seismic damage from ductility and hysteretic energy demands in equivalent oscillators using linear response

Estimation of damage in a structure under anticipated seismic events is important for its performance-based design. This can be done in terms of the ductility and hysteretic energy demands for each of the anticipated plastic hinges under the anticipated ground motions. This study considers the possibility of quantifying the structural damage simply from the linear analysis based on the elastic design spectra of the ground motions and undamped mode shapes of the structure. A two-parameter model is first developed for the estimation of hysteretic energy demand in single-degree-of-freedom (SDOF) oscillators for five types of nonlinearities from the linear displacement peaks. The parameters of this model are estimated for various initial periods, nonlinearity types, and specific values of damping ratio, maximum possible ductility demand, and hysteretic parameters. Next, it is assumed that damage in each of the equivalent oscillators corresponding to different modes of vibration of the structure can be combined to quantify the structural damage. The hysteretic properties of these equivalent oscillators are estimated in the cases of 2-DOF and 3-DOF frames, and linear-peaks-based models for ductility demand and hysteretic energy demand are then used to estimate damage index for each of these oscillators. Finally, a combination rule is proposed to suitably combine these damage indices and thus estimate the extent of overall damage. A numerical study with the help of a suite of 100 ground motions illustrates how the proposed methodology estimates the damage levels of 2-DOF and 3-DOF example frames with strain-hardening bilinear and stiffness-degrading Riddell-Newmark type nonlinearities in the moment–curvature relationships of their column sections.

Modal analysis for implant stability assessment: Sensitivity of this methodology for different implant designs

ObjectiveTo investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis. MethodsSix implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch (‘long branch’ and ‘short branch’) in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes. ResultsWith reference to the ‘long branch’ model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with the exception of the initial condition (1% bone maturation) where the implant is not osseointegrated. By contrast, implant displacements become relevant in the ‘short branch’ model, unless osseointegration level is beyond 20%. The difference between resonance frequency at whole bone maturation and resonance frequency at 1% bone maturation remained lower than 6.5% for all modes, with the exception of the third mode of vibration in the ‘D’ implant where this difference reached 9.7%. With reference to the ‘short branch’, considering the first mode of vibration, 61–68% of the frequency increase was achieved at 10% osseointegration; 72–79% was achieved at 20%; 89–93% was achieved at 50% osseointegration. The pattern of the natural frequency versus the osseointegration level is similar among different modes of vibration. SignificanceResonance frequencies and their trends towards osseointegration level may differ between implant designs, and in different boundary conditions that are related to implant position inside the mandible; tapered implants are the most sensitive to bone maturation levels, small implants have very little sensitivity. Resonance frequencies are less sensitive to bone maturation level beyond 50%.

DFT Study for the Spectroscopic and Structural Analysis of p-Dimethylaminoazobenzene

The study under consideration represents the computational calculations of Azo-based direct dye named p-(dimethylamino)azobenzene (DMAB) under the effect of solvents with different relative permittivities. A density functional theory (DFT) method at the B3LYP level with 6-311G++ was applied for the spectroscopic and structural analysis of the title compound. Calculations of geometric parameters (bond orders, bond lengths, and dihedral angles), electron densities, thermodynamic parameters, and orbital energies were performed for the title compound. Mulliken population analysis (MPA) as well as natural population analysis (NPA) was also performed at the B3LYP level with different solvents for finding solvent effects. In order to predict the reactivity of DMAB, molecular electrostatic potential (MESP) calculations were carried out for it. For vibrational analysis, the infrared (IR) spectra were computed for the title compound at the B3LYP/6-311G++ level in the gas phase and in different solvents with good agreement to the experimental FT-IR spectrum. The different modes of vibrations were assigned using potential energy distribution (PED). The computed Raman spectra also showed appreciable agreement with the experimental recorded Raman spectrum. The electronic absorption spectra of the title compound have been computed employing DFT/B3LYP with the 6-311G++ basis set in the gas phase and in four different solvents, that is, DMSO, ethanol, acetonitrile, and water which were compared with the experimental spectra with appreciable agreement. NBO analysis was carried out for understanding the intramolecular and intermolecular bonding of the compound and the density transfer from completely filled to unfilled orbital was found. The HOMO-LUMO energies were determined for analyzing the mechanism of intramolecular charge transfer.

Development and Analysis of Human Hand-Arm System Model for Anti-Vibration Isolators

The potential health injuries associated with human hand-transmitted mechanical vibration which caused during driving vehicles, and operating on hand-held power tools. In this study five Degree-of-Freedom (DOF) human hand-arm system model is developed to analyze HAS model in terms of acceleration responses. The study analysed one of the possible protective way to reduce hand-transmitted vibration by using the anti-vibration isolators to machine handle. This study presents biomechanical models consisting deflection patterns due to masses at the finger, palm-wrist and upper-arm, corresponding to different modes of vibration, subject to z-axis vibration. A MATLAB-SIMULINK based model is also developed to determine the effect of vibration transmission from machine tool handle. The anti-vibration isolators have been introduced as a gripper of machine tool handle and simulation results shows significantly better damping characteristics and reduction of the vibration transmission effect to HAS.

Formula omitted]-deformed Einstein’s model to describe specific heat of solid

Realistic phenomena can be described more appropriately using generalized canonical ensemble, with proper parameter sets involved. We have generalized the Einstein’s theory for specific heat of solid in Tsallis statistics, where the temperature fluctuation is introduced into the theory via the fluctuation parameter q. At low temperature the Einstein’s curve of the specific heat in the nonextensive Tsallis scenario exactly lies on the experimental data points. Consequently this q-modified Einstein’s curve is found to be overlapping with the one predicted by Debye. Considering only the temperature fluctuation effect(even without considering more than one mode of vibration is being triggered) we found that the CV vs T curve is as good as obtained by considering the different modes of vibration as suggested by Debye. Generalizing the Einstein’s theory in Tsallis statistics we found that a unique value of the Einstein temperature θE along with a temperature dependent deformation parameter q(T), can well describe the phenomena of specific heat of solid i.e. the theory is equivalent to Debye’s theory with a temperature dependent θD.

Design of a Testing Facility for Investigation of Drill Pipes Fatigue Failure

Drillstring and down-hole tool failure usually results from failing to control one or more of the vibration mechanisms. The solution starts with the ability to measure different modes of vibration, hence identifying different vibration mechanisms. Lateral, torsion and axial are vibration modes that take place when drill pipes run into problems downhole. Due to the three modes of vibration mechanisms such as bit bounce, stick-slip, lateral shocks, bit and bottom hole assembly (BHA) whirl, parametric and torsional resonance occur. Understanding the causes of the destructive loads is the main step towards developing approaches to prevent or reduce their effects, hence improving drilling performance. Vibration modes and mechanisms lead to failure of the drill pipes, BHA and drill bits. Drill pipes fatigue failure is very common due to capability of producing all vibration modes and mechanisms. Drill pipe and downhole tool assembly failure usually result from failing to have power over one or more of these vibration mechanisms. A novel in house experimental setup has been developed to mimic downhole axial, lateral and torsional vibration modes and mechanisms in drilling operations. In this paper, we focus on the design and construction of the testing facility. A number of tests were conducted to validate the capability and performance of the test setup. Drill pipe fatigue failure due to lateral cyclic stresses induced in the drill pipe has also been investigated and presented in this paper. The results show that operating on a rotation speed higher than 90% of the drillstring critical speed leads to yielding in the drillstring.

Model-based analysis of construction design of technological adapter for magnetic-pulse processing of plants in horticulture

The article analyzes the features of design of an adapter unit for magnetic-pulse processing (MPP) of plants. It is necessary for radiation of plants by a low frequency 0-100 Hz magnetic field with simultaneous additional synchronous exposure to light with 445-650 nm waves. Classification of the agricultural technological adapters is presented. Analysis of it showed that the electrocylinders with electronic control elements placed on a frame are suitable for construction of a technological adapter of MPP of plants better. In a software environment of Solid Works/Simulation by means of the module of physical simulation the authors visualized the kinematic 3D model of the technological adapter and create a mesh Finite Element Analysis. The studied model placed at fixing three-point hinged system. Load of 50 N was applied to the guideway in the place of fastening of the working elements MPP over the entire surface. The dynamic characteristics of technological adapter MPP, frequency analysis, analysis of stress-strain state of the structure and its components were estimated. The resonance frequencies values were obtained. Zones of concentration of tension 50 mm apart the upper point of fixing of the actuator to a guideway were determinated. Their maximum values reach 40 MPas. Features of distribution of tension dispersion of in these zones are revealed, spectrum of the equivalent tension of model are received. The resonance frequencies equal 0.2-9.2 I rad/s at different modes of vibration of the technological adapter. Resistance to impact of sinusoidal vibration is revealed. The found resonance frequencies are outside the range of the frequencies influencing the technological adapter in case of its operation and transportation. The modelling uncertainty is not more than 5 percent. In case of loading of the technological adapter with MPP working elements (magnetic inductors) of 50 N vertical offset of a guideway makes 1.16 mm. The developed technological adapter of manipulyatorny type, with the simplified construction and the reduced metal consumption, allows to automate completely magnetic-pulse processing of plants with a possibility of automatic adjustment to different agrotechnological parameters of plantings. Frequency of impulse and luminous radiation and time of exposure is showed on control box of the electronic device. Use of special technical means for impulse magnetic processing of garden cultures improves a rooting ability of cherry cuttings by 1.8 times, black chokeberry - by 1,4, blackberry and raspberry - by 1.5-2.0, honeysuckles - by 1.4 times in comparison with the untreated cuttings. The quantity of roots at the same time increases by 21-48 percent, length - for 25-61 percent. Application of MPP when growing of the implanted cuttings in the greenhouse increases survival obyf blackberry by 10 percent, honeysuckles - on 18, mountain ashes - by30 percent. The amount of cuttings growth increases by 14-46 percent.

DTA and FTIR of 70TeO2–(25 − x)MnO2–xV2O5–5Fe2O3 tellurite glass systems

A series of quaternary tellurite glasses in the form of 70TeO2–(25 − x)MnO2–xV2O5–Fe2O3 where (0 ≤ x ≤ 25 mol%) have been prepared by the conventional melt quenching technique. Differential thermal analysis (DTA) curves of these glasses have been investigated in the temperature range 300–1093 K and at different heating rates a = (2.5, 5, 10, 20 and 40 K min−1). The glass transition temperature (T g), the crystallization temperature (T P), the glass stability (∆T) and the activation energy for crystallization have been measured. The glass transition temperature has been analyzed according to the average cross-link density, and the average stretching force constant is present in the glass. FTIR investigations showed that the absorption bands of different modes of vibration in the manganese tellurite network were shifted toward higher wave number.

Vibration fatigue using modal decomposition

Abstract Vibration-fatigue analysis deals with the material fatigue of flexible structures operating close to natural frequencies. Based on the uniaxial stress response, calculated in the frequency domain, the high-cycle fatigue model using the S-N curve material data and the Palmgren-Miner hypothesis of damage accumulation is applied. The multiaxial criterion is used to obtain the equivalent uniaxial stress response followed by the spectral moment approach to the cycle-amplitude probability density estimation. The vibration-fatigue analysis relates the fatigue analysis in the frequency domain to the structural dynamics. However, once the stress response within a node is obtained, the physical model of the structure dictating that response is discarded and does not propagate through the fatigue-analysis procedure. The structural model can be used to evaluate how specific dynamic properties (e.g., damping, modal shapes) affect the damage intensity. A new approach based on modal decomposition is presented in this research that directly links the fatigue-damage intensity with the dynamic properties of the system. It thus offers a valuable insight into how different modes of vibration contribute to the total damage to the material. A numerical study was performed showing good agreement between results obtained using the newly presented approach with those obtained using the classical method, especially with regards to the distribution of damage intensity and critical point location. The presented approach also offers orders of magnitude faster calculation in comparison with the conventional procedure. Furthermore, it can be applied in a straightforward way to strain experimental modal analysis results, taking advantage of experimentally measured strains.

Spectra, electronic structure and molecular docking investigations on 3-(phenyl(p-tolylamino)methyl)naphthalen-2-ol – An experimental and computational approach

A combined experimental and theoretical study on synthesis, molecular structure, vibrational analysis, natural bond orbitals, electronic structure, hyperpolarizability, thermochemical properties has been reported for 3-(phenyl(p-tolylamino)methyl) naphthalen-2-ol (PTMN). The FT-IR spectrum was recorded in the range 4000–400 cm−1 and FT-Raman spectrum was recorded in the range 4000–50 cm−1. Sadlej pVTZ basis set was used to calculate the molecular geometry and the vibrational spectra. Natural bond orbital analysis (NBO) were calculated for PTMN using Density Functional Theory (DFT) based on B3LYP/6-311G(d,p) model chemistry. The potential energy distribution (PED) was derived to deepen the understanding on different modes of vibrations which are contributed by respective wavenumber. The molecular structure of PTMN was confirmed also with the simulation of NMR spectrum was performed using GIAO strategy by using B3LYP/6-311G(d,p). The non-linear nature of PTMN was confirmed by hyperpolarizabilty examination. The docking results suggest that the PTMN might exhibit inhibitory activity against protein induce Alopecia disease. The experimental UV–Visible spectra was recorded in the region of 600–200 nm and correlated with simulated spectra by suitable solvated PBEPBE/6-311G(d,p) model. The properties of HOMO-LUMO energies were measured by DFT approaches. In addition, the molecular electrostatic potential (MEP) was computed and investigated. Thermal properties are theoretically calculated that are obtained from the thermochemistry results against a range of temperatures.

Vortex-induced vibrations of a vertical riser with time-varying tension

Numerical simulations of a vertical tensioned riser in a sheared flow are performed, where the riser top end oscillates sinusoidally in the vertical direction. The oscillating top-end motion causes tension variations and changes in the natural frequencies of the riser. The flow around the structure causes vortex shedding, oscillating lift forces and vortex-induced vibrations (VIV). It is well-known that the vortex shedding is affected by structure motion, and may lock on to the riser’s natural frequencies. However, the vortex shedding frequency must remain close to the Strouhal frequency, and may therefore excite different modes of vibration as the riser tension changes. With this in mind, the overall aim of this paper is to investigate how tension variations affect the VIV response. The riser dynamics are simulated in time domain using a non-linear finite element structural model combined with an empirical hydrodynamic load model. The latter includes a synchronization model which simulates how the vortex shedding reacts to the structure motion to obtain lock-in. Simulations are run using different amplitudes and frequencies for the top-end motion, and the resulting cross-flow displacements and bending strains are studied. The results show that, when the riser top-end oscillates, the VIV response contains several modes, and the dominating mode may vary with time. The number of active modes are found to be strongly dependent on the period of the riser tension.

Evaluation of frequency excitation of helical suspension spring using finite element analysis

Frequency response analysis is a technique used to determine the steady-state response of a linear structure to loads that vary harmonically with time. The aim is to calculate the structure's response at several frequencies and obtain results as response quantity versus frequency or time using finite element analysis. Peak responses are then identified on the graph and stresses reviewed at those peak frequencies. This paper discusses the modal and harmonic or frequency response of helical suspension spring of rail road vehicle using finite element tool ANSYS for different harmonic forces on inner and composite springs. The experimental result of accelerometer has been recorded for maximum speed of 80 km/hr determines excitations for amplitude of acceleration of suspension system versus time. Modal analysis finds the natural frequencies of spring for different modes of vibration for inner and composite assembly of spring and harmonic analysis of undamped suspension system reveals peak amplitude of stress and acceleration for the frequency range of 0 Hz to 50 Hz. The analysis reveals that the maximum amplitudes occurred at frequency of 40 Hz for inner spring and 35 Hz for composite spring which is nearer to theoretical natural frequency of inner spring 38.06 Hz.

Evaluation of frequency excitation of helical suspension spring using finite element analysis

Frequency response analysis is a technique used to determine the steady-state response of a linear structure to loads that vary harmonically with time. The aim is to calculate the structure's response at several frequencies and obtain results as response quantity versus frequency or time using finite element analysis. Peak responses are then identified on the graph and stresses reviewed at those peak frequencies. This paper discusses the modal and harmonic or frequency response of helical suspension spring of rail road vehicle using finite element tool ANSYS for different harmonic forces on inner and composite springs. The experimental result of accelerometer has been recorded for maximum speed of 80 km/hr determines excitations for amplitude of acceleration of suspension system versus time. Modal analysis finds the natural frequencies of spring for different modes of vibration for inner and composite assembly of spring and harmonic analysis of undamped suspension system reveals peak amplitude of stress and acceleration for the frequency range of 0 Hz to 50 Hz. The analysis reveals that the maximum amplitudes occurred at frequency of 40 Hz for inner spring and 35 Hz for composite spring which is nearer to theoretical natural frequency of inner spring 38.06 Hz.