scholarly journals Study of the Fatigue Life and Weight Optimization of an Automobile Aluminium Alloy Part under Random Road Excitation

2010 ◽  
Vol 17 (2) ◽  
pp. 107-121 ◽  
Author(s):  
A. Saoudi ◽  
M. Bouazara ◽  
D. Marceau
Keyword(s):  
Fatigue Life ◽  
Aluminium Alloy ◽  
Natural Frequencies ◽  
Vehicle Suspension ◽  
Critical Element ◽  
Alloy Sample ◽  
Weight Optimization ◽  
Frequency Range ◽  
Power Spectral ◽  
Road Excitation

Weight optimization of aluminium alloy automobile parts reduces their weight while maintaining their natural frequency away from the frequency range of the power spectral density (PSD) that describes the roadway profile. We present our algorithm developed to optimize the weight of an aluminium alloy sample relative to its fatigue life. This new method reduces calculation time; It takes into account the multipoint excitation signal shifted in time, giving a tangle of the constraint signals of the material mesh elements; It also reduces programming costs. We model an aluminium alloy lower vehicle suspension arm under real conditions. The natural frequencies of the part are inversely proportional to the mass and proportional to flexural stiffness, and assumed to be invariable during the process of optimization. The objective function developed in this study is linked directly to the notion of fatigue. The method identifies elements that have less than 10% of the fatigue life of the part's critical element. We achieved a weight loss of 5 to 11% by removing the identified elements following the first iteration.

scholarly journals Vibration Characteristics Analysis of Convalescent-Wheelchair Robots Equipped with Dynamic Absorbers

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Song Wang ◽  
Leilei Zhao ◽  
Yanzhu Hu ◽  
Fuxing Yang
Keyword(s):  
Vibration Isolation ◽  
Natural Frequencies ◽  
The Road ◽  
Power Spectral ◽  
Vibration Model ◽  
Characteristics Analysis ◽  
Vibration Responses ◽  
Road Excitation ◽  
Dynamic Absorber ◽  
Numerical Calculation Method

To provide a theoretical guidance for the vibration isolation design, the vibration responses characteristics for the convalescent-wheelchair robot with DA (dynamic absorber) undergoing the random road were revealed. Firstly, the vibration model of the convalescent-wheelchair system with DA was created. The frequency response functions of the road excitation velocity to the convalescent acceleration, the wheelchair body acceleration, and the tire dynamic deflection were deduced. Then, the numerical calculation method of the PSD (power spectral density) and the RMS (root mean square) responses were proposed. Thirdly, the vibration isolation performances of the wheelchair robot with DA and without DA were compared. Finally, the sensitivity analysis of the vibration responses to the mass ratios, the damping ratios, and the natural frequencies was carried out to reveal the effects of the parameters on the vibration responses. The results show that the DA can partly suppress the vibration of the convalescent and the wheelchair body, especially in the resonance area of the wheelchair body. However, the DA cannot successfully improve the tire contact behavior.

A Pneumatic Artificial Muscle Bionic Kangaroo Leg Suspension

2019 ◽  
Vol 12 (4) ◽  
pp. 357-366
Author(s):  
Yong Song ◽  
Shichuang Liu ◽  
Jiangxuan Che ◽  
Jinyi Lian ◽  
Zhanlong Li ◽  
...  
Keyword(s):  
Strong Shock ◽  
Artificial Muscle ◽  
Suspension System ◽  
Vehicle Body ◽  
Vehicle Suspension ◽  
Pneumatic Artificial Muscle ◽  
Advantages And Disadvantages ◽  
Road Excitation ◽  
Vehicle Suspension System ◽  
Suspension Structure

Background: Vehicles generally travel on different road conditions, and withstand strong shock and vibration. In order to reduce or isolate the strong shock and vibration, it is necessary to propose and develop a high-performance vehicle suspension system. Objective: This study aims to report a pneumatic artificial muscle bionic kangaroo leg suspension to improve the comfort performance of vehicle suspension system. Methods: In summarizing the existing vehicle suspension systems and analyzing their advantages and disadvantages, this paper introduces a new patent of vehicle suspension system based on the excellent damping and buffering performance of kangaroo leg, A Pneumatic Artificial Muscle Bionic Kangaroo Leg Suspension. According to the biomimetic principle, the pneumatic artificial muscles bionic kangaroo leg suspension with equal bone ratio is constructed on the basis of the kangaroo leg crural index, and two working modes (passive and active modes) are designed for the suspension. Moreover, the working principle of the suspension system is introduced, and the rod system equations for the suspension structure are built up. The characteristic simulation model of this bionic suspension is established in Adams, and the vertical performance is analysed. Results: It is found that the largest deformation happens in the bionic heel spring and the largest angle change occurs in the bionic ankle joint under impulse road excitation, which is similar to the dynamic characteristics of kangaroo leg. Furthermore, the dynamic displacement and the acceleration of the vehicle body are both sharply reduced. Conclusion: The simulation results show that the comfort performance of this bionic suspension is excellent under the impulse road excitation, which indicates the bionic suspension structure is feasible and reasonable to be applied to vehicle suspensions.

scholarly journals Aspects of Strength Testing of Tank Containers in Compliance with the Requirements of the UN Navigation Rules and Regulations

2021 ◽  
Vol 9 (3) ◽  
pp. 349
Author(s):  
Andrii Sulym ◽  
Pavlo Khozia ◽  
Eduard Tretiak ◽  
Václav Píštěk ◽  
Oleksij Fomin ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Response Spectrum ◽  
Experimental Curve ◽  
Bulk Liquid ◽  
Frequency Range ◽  
Test Configuration ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Spectrum Curve ◽  
The Impact

This article deals with the method of computer-aided studies of the results of tank container impact tests to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped test rig or using a railway flat car by impacting a flat car with a striking car, in compliance with the requirements of the UN Navigation Rules and Regulations. It is shown that the main assessed characteristic of the UN requirements is the spectrum of the shock response (accelerations) for the interval natural frequencies of the shock pulse. The calculation of the points of the shock response spectrum curve based on the test results is reproduced in four stages. A test configuration of the impact testing of the railway flat car with a tank container is presented, and the impact is performed in such a way that, under a single impact, the shock spectrum curve obtained during the tests for both fittings subjected to impact repeats or exceeds the minimum shock spectrum curve for all frequencies in the range of 2 Hz to 100 Hz. Formulas for determining the relative displacements and accelerations for the interval natural frequencies of the shock wave are given. The research results are presented in graphical form, indicating that the experimental values of the shock response spectrum exceed the minimum permissible values; the equation of the experimental curve of the shock response spectrum in the frequency range 0–100 Hz is described by power-law dependence. The coefficients of the equation were determined by the statistical method of maximum likelihood with the determination factor being 0.897, which is a satisfactory value; a comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0–100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. A new test configuration is proposed using a tank car with a bulk liquid, the processes in which upon impact differ significantly from other freight wagons under longitudinal impact loads of the tank container. The hydraulic impact resulting from the impact on the tank container and the platform creates an overturning moment that causes the rear fittings to be unloaded.

scholarly journals Detection and localization of multiple small damages in beam

2021 ◽  
Vol 13 (1) ◽  
pp. 168781402098732
Author(s):  
Ayisha Nayyar ◽  
Ummul Baneen ◽  
Syed Abbas Zilqurnain Naqvi ◽  
Muhammad Ahsan
Keyword(s):  
Frequency Response ◽  
Natural Frequencies ◽  
Signal To Noise Ratio ◽  
Moving Average ◽  
A Priori ◽  
Damage Index ◽  
High Signal ◽  
Frequency Range ◽  
Spatial Locality ◽  
System Frequency

Localizing small damages often requires sensors be mounted in the proximity of damage to obtain high Signal-to-Noise Ratio in system frequency response to input excitation. The proximity requirement limits the applicability of existing schemes for low-severity damage detection as an estimate of damage location may not be known  a priori. In this work it is shown that spatial locality is not a fundamental impediment; multiple small damages can still be detected with high accuracy provided that the frequency range beyond the first five natural frequencies is utilized in the Frequency response functions (FRF) curvature method. The proposed method presented in this paper applies sensitivity analysis to systematically unearth frequency ranges capable of elevating damage index peak at correct damage locations. It is a baseline-free method that employs a smoothing polynomial to emulate reference curvatures for the undamaged structure. Numerical simulation of steel-beam shows that small multiple damages of severity as low as 5% can be reliably detected by including frequency range covering 5–10th natural frequencies. The efficacy of the scheme is also experimentally validated for the same beam. It is also found that a simple noise filtration scheme such as a Gaussian moving average filter can adequately remove false peaks from the damage index profile.

Influence of Impact-Oscillatory Loading on Fatigue Life of Aluminium Alloy 2024-T351

2021 ◽  
Author(s):  
Mykola Chausov ◽  
Elena Zasimchuk ◽  
Pavlo Maruschak ◽  
Oleg Khyzhun ◽  
Andrii Pylypenko ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Aluminium Alloy

Numerical and Experimental Studies of Pipe Vibration Generated by Elongated Orifice

2016 ◽  
Author(s):  
Wenjie Bai ◽  
Quan Duan ◽  
Zaoxiao Zhang
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Flow Rate ◽  
Vibration Response ◽  
Frequency Range ◽  
Fluctuating Pressure ◽  
Outlet Pressure ◽  
Wall Pressure Fluctuations ◽  
Power Spectral ◽  
Pipe Vibration

Hydraulic tests for elongated orifice-induced wall pressure fluctuations and vibration in pipeline have been carried out. The regulating modes of test system consist of maintaining outlet pressure to increase flow rate and maintaining flow rate to decrease outlet pressure. Both regulating modes would increase the possibility of cavitation within elongated orifice, which has been confirmed by numerical simulation in present study. Statistical characteristics of the fluctuating pressure and structure vibration response have been studied. The standard deviation analyses indicate that the amplitude of fluctuating pressure is mainly determined by flow rate. The power spectral density analyses show that the energy of the fluctuating pressure behind elongated orifice is concentrated in lower frequency range and it can be divided into two parts in this test: the pressure pulsation excited by plunger pump and the random fluctuating pressure produced by elongated orifice’s disturbance. The power spectral density of pipe vibration response shows that the lower frequency of pipe vibration response can be ascribed to the fluctuating pressure behind elongated orifice and the characteristic frequencies corresponding to cavitation within elongated orifice are in the higher frequency range.

SIMP for Complex Structures

2016 ◽  
Vol 846 ◽  
pp. 535-540
Author(s):  
David J. Munk ◽  
David W. Boyd ◽  
Gareth A. Vio
Keyword(s):  
Natural Frequencies ◽  
Dynamic Loads ◽  
Topology Optimisation ◽  
Complex Structures ◽  
Structural Failure ◽  
Frequency Range ◽  
Aerodynamic Loading ◽  
Frequency Excitation ◽  
Wing Structure ◽  
Lifting Surfaces

Designing structures with frequency constraints is an important task in aerospace engineering. Aerodynamic loading, gust loading, and engine vibrations all impart dynamic loads upon an airframe. To avoid structural resonance and excessive vibration, the natural frequencies of the structure must be shifted away from the frequency range of any dynamic loads. Care must also be taken to ensure that the modal frequencies of a structure do not coalesce, which can lead to dramatic structural failure. So far in industry, no aircraft lifting surfaces are designed from the ground up with frequency optimisation as the primary goal. This paper will explore computational methods for achieving this task.This paper will present a topology optimisation algorithm employing the Solid Isotropic Microstructure with Penalisation (SIMP) method for the design of an optimal aircraft wing structure for rejection of frequency excitation.

scholarly journals Experimental Design and Validation of an Accelerated Random Vibration Fatigue Testing Methodology

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Jiang ◽  
Gun Jin Yun ◽  
Li Zhao ◽  
Junyong Tao
Keyword(s):  
Fatigue Life ◽  
Stress Responses ◽  
Life Prediction ◽  
Random Vibration ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Power Spectral ◽  
Vibration Fatigue ◽  
Non Gaussian

Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a notched specimen structure were measured under different base random excitations. According to the measured stress responses, the structural fatigue lives corresponding to the different vibrational excitations were predicted by using the WAFO simulation technique. Second, a couple of destructive vibration fatigue tests were carried out to validate the accuracy of the WAFO fatigue life prediction method. After applying the proposed experimental and numerical simulation methods, various factors that affect the vibration fatigue life of structures were systematically studied, including root mean squares of acceleration, power spectral density, power spectral bandwidth, and kurtosis. The feasibility of WAFO for non-Gaussian vibration fatigue life prediction and the use of non-Gaussian vibration excitation for accelerated fatigue testing were experimentally verified.

scholarly journals Effects of Hard Surface Grinding and Activation on Electroless-Nickel Plating on Cast Aluminium Alloy Substrates

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Olawale Olarewaju Ajibola ◽  
Daniel T. Oloruntoba ◽  
Benjamin O. Adewuyi
Keyword(s):  
Aluminium Alloy ◽  
Electroless Nickel ◽  
Sodium Hypophosphite ◽  
Palladium Chloride ◽  
Alloy Sample ◽  
Sand Cast ◽  
Hard Surface ◽  
Cast Aluminium ◽  
Surface Polishing ◽  
Cylinder Piston

This work examined effects of hard surface polishing grits and activation on electroless-nickel (EN) plating on cast aluminium alloy substrates in sodium hypophosphite baths. As-received aluminium alloy sample sourced from automobile hydraulic brake master cylinder piston was melted in electric furnace and sand cast into rod. The cast samples were polished using different grits (60 μm–1200 μm) before plating. The effects on adhesion, appearance, and quantity of EN deposits on substrates were studied. Observation shows that the quantity of EN deposit is partly dependent on the alloy type and roughness of the surface of the substrates, whereas the adhesion and brightness are not solely controlled by the degree of surface polishing. The best yield in terms of adhesion and appearance was obtained from the activation in zincate and palladium chloride solutions. Higher plating rates (g/mm2/min) of 3.01E-05, 2.41E-05, and 2.90E-05 were obtained from chromate, zincate, and chloride than 8.49E-06, 8.86E-06, and 1.69E-05 as obtained from HCl etched, NaOH, and H2O activated surfaces, respectively.

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