| 1. |
- Aidanpää, Jan-Olov
(författare)
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Review of Mechanical Vibrations by S.S. Rao
- 2007
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 221:1, s. 135-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Baghdadchi, Amir, 1994-, et al.
(författare)
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Consumable pin-friction stir spot welding of Al-Mg-Si alloy via pre-created hole and refilling : Microstructure evolution, defects, and shear/tensile failure load
- 2023
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : Sage Publications. - 0954-4062 .- 2041-2983. ; 237:17
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Tidskriftsartikel (refereegranskat)abstract
- Since Al-Mg-Si alloys are widely used in the transportation industry, it is important to produce a sound and robust weld between the sheets of these alloys. The focus of this work is on the tensile-shear and cross-tension strengths of the consumable pin-friction stir spot welds (CP-FSSWs) without an exit-hole between the Al-6061 aluminum sheets. Before welding, a hole was created at the joint region in the base sheets and then, it was filled using a rotating consumable pin. The tensile-shear, cross-tension, and microhardness tests were employed to evaluate the mechanical properties of the spot welds. The results showed that the pre-created hole was entirely filled during the welding process. While a complete bond was formed between the consumable pin and the lateral surface of the hole, there were three distinct regions at the interface of the pin and the bottom of the hole: complete bond, kissing bond, and defects. Enhancement of the tool rotational speed decreased the area of the complete bond in the weld compared to the other regions. A linear relationship existed between the bonding area and weld failure load in the cross-tension test. The proposed relationship approved the impact of the swirly region at the interface of the base sheets on the weld strength. While in the cross-tension test, the weld failure load decreased from ∼2800 to ∼1950 N, it improved from ∼10,500 to ∼12,000 N in the tensile-shear test with enhancement of the tool rotational speed from 700 to 2000 rpm. The hardness measurements demonstrated that there was no common heat affected zone softening after CP-FSSW.
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| 3. |
- Bergstedt, Edwin, et al.
(författare)
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Influence of gear surface roughness on the pitting and micropitting life
- 2020
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : SAGE Publications Ltd. - 0954-4062 .- 2041-2983. ; 234:24, s. 4953-4961
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Tidskriftsartikel (refereegranskat)abstract
- Pitting and micropitting are the two main gear rolling contact fatigue modes. It is widely accepted that micropitting will lead to pitting; however, the relationship between pitting and micropitting life needs further investigation. In this work, micropitting and pitting tests were performed on an FZG back-to-back test rig using standard FZG PT-C and GF-C gears. The gear tooth profile change due to micropitting and pitting damage was measured in situ in the gearbox using a profilometer after each test. The gear surface roughness parameters were calculated from the measured tooth profile. A Gaussian low pass filter with cut off length (Formula presented.) mm was applied to the measured tooth profile to obtain the waviness. The calculated roughness parameters and the obtained tooth profile with waviness for each test were imported into the KISSsoft software to calculate the contact stress and specific film thickness at the corresponding load stage. Experimental results show that smooth gear surface can reduce or even avoid micropitting damage, but could lead to a reduction in pitting life.
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| 4. |
- Bidabadi, M, et al.
(författare)
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The analytical investigation of premixed combustion in cylindrical micro-combustor
- 2011
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. - 2041-2983 .- 0954-4062. ; 225:4, s. 931-938
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Tidskriftsartikel (refereegranskat)abstract
- In this study, an analytical model for heat recirculation in cylindrical micro-combustorsis presented, including the effects of heat transfer from the product gas stream in the reaction zoneand post-flame region to the reactant in the preheat zone, structural heat conduction through thecombustor walls and heat loss to ambient. Eventually, the explicit expression for the flame speedin non-adiabatic condition and the implicit expression for adiabatic condition are obtained in thisresearch. In addition, comparison is made between adiabatic and non-adiabatic flame speeds.It is demonstrated that the streamwise heat conduction through the structure of combustorplays an important role in the flame broadening in both adiabatic and non-adiabatic conditions.Moreover, it is shown that reducing the size of the combustor to a submillimetre scale extremelyincreases the surface-to-volume ratio, leading to the decrease in the flame speed and flamequenching.
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| 5. |
- Calleecharan, Yogeshwarsing, et al.
(författare)
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Dynamics of a hydropower generator subjected to unbalanced magnetic pull
- 2011
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 225:9, s. 2076-2088
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Tidskriftsartikel (refereegranskat)abstract
- Eccentricity leading to unbalanced magnetic pull (UMP) in electrical machines is a significant concern in industry. The UMP is known to be composed of two components: a radial component and a tangential one. Models that are used in industry tend to include the radial component alone. In this article, a Jeffcott rotor model together with a new UMP model that incorporates both radial and tangential UMP constituents is studied for an industrial hydropower generator. Characterizing the UMP as springs permits the model to inherit UMP stiffness contribution. Interesting dynamics are observed with the new model for a wide range of external forcing frequencies. It is shown firstly that the new UMP model is sensitive to forcing frequency in the rotor movements. Secondly, it is found that this sensitivity to forcing frequency increases with decreasing rotor system stiffness. Moreover, quasi-periodic motion in the rotor displacements is observed and it is noted that the rotor does not need to be forced by frequencies above its critical speed for this less desirable motion to occur. Thus, it becomes interesting to be able to account for the UMP stiffness contribution in order to curb machine malfunction which might result from these UMP forces
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| 6. |
- CHEN, LING, et al.
(författare)
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Quantitative study of roughness effect in nanoindentation on AISI316L based on simulation and experiment
- 2017
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Ingår i: Proceedings of the Institution of Mechanical Engineers. Part C: Journal of Mechanical Engineering Science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 231:21, s. 4067-4075
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Tidskriftsartikel (refereegranskat)abstract
- In nanoindentation, roughness of the sample surface can be a severe source of error in the determination of properties from indentation tests. Recently, roughness was also considered as a crucial issue in understanding the indentation size effect where a significant increase in hardness was seen with the decrease of depth. A three-dimensional roughness model with the Johnson–Cook material model is employed to study the roughness effect in nanoindentation on AISI316L stainless steel by use of finite element method. The rough surface is obtained by generating a random function in Matlab and then applying fast Fourier transform. With the quantitative analysis the mechanical properties such as the hardening and variation of the reduced modulus are found. From both the experimental and simulation results, the hardness distribution shows strengthening effect with the increased surface roughness. Both the scatter of hardness and indentation modulus increases with the increased roughness. In addition, the dependence of the pile-up effect and the contact area on the roughness is studied and analyzed.
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| 7. |
- Duraisamy, Palmani, et al.
(författare)
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Real-time implementation of deep reinforcement learning controller for speed tracking of robotic fish through data-assisted modeling
- 2024
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : Sage Publications. - 0954-4062 .- 2041-2983. ; 238:2, s. 572-585
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Tidskriftsartikel (refereegranskat)abstract
- This article proposes real-time speed tracking of two-link surface swimming robotic fish using a deep reinforcement learning (DRL) controller. Hydrodynamic modelling of robotic fish is done by virtue of Newtonian dynamics and Lighthill’s kinematic model. However, this includes external unsteady reactive forces that cannot be modeled accurately due to the distributed nature of hydrodynamic behavior. Therefore, a novel data-assisted dynamic model and control method is proposed for the speed tracking of robotic fish. Initially, the cruise speed motion data are collected through experiments. The water-resistance coefficient is estimated using the least mean square fit, which is then adopted in the model. Subsequently, a closed-loop discrete-time DRL controller trained through a soft actor-critic (SAC) agent is implemented through simulations. SAC overcomes the brittleness problem encountered by other policy gradient approaches by encouraging the policy network for maximum exploration and not assigning a higher probability to any single part of actions. Due to this robustness in the policy learning, the convergence error becomes low in RL-SAC than RL-DDPG controller. The simulation results verify that the DRL-SAC control with data-assisted modelling substantially improves the speed tracking performance. Further, this controller is validated in real-time, and it is observed that the SAC-trained controller tracks the desired speed more accurately than the DDPG controller.
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| 8. |
- Furustig, Joel, et al.
(författare)
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A strategy for wear analysis using numerical and experimental tools, applied to orbital type hydraulic motors
- 2016
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 230:12, s. 2086-2097
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Tidskriftsartikel (refereegranskat)abstract
- An accurate and reliable wear analysis requires detailed knowledge of the tribological conditions of the studied system. In this work, a numerical model which can quantify wear and is applicable to hydraulic motors is developed. Detailed tribological knowledge can be acquired through strategic experimental testing and numerical simulations. The model is constructed to include the effect on wear from varying lubricant film thickness. The development of the wear model includes consideration of wear observed in the Scanning Electron Microscopy (SEM) analysis of tested motors. The model is of the Archard type, in which the k-value is estimated from experiments, after considering the effect of lubrication. The contact pressure is the solution to a lubrication model that governs both the hydrodynamics of the lubricant film and the direct contact between the rough surfaces. To validate the model, a hydraulic motor is run at different operating conditions and the apparent wear depth is analysed after the tests. Numerical simulations mimicking the same configuration are performed and the predicted wear depths are compared to the experimental results. Similarities and differences are discussed and it is evident that a clear correlation exists between the wear predicted with the model and the measurement data of the apparent wear in the hydraulic motor. There are also discrepancies because of the model simplicity and the uncertainty in the specifications of the tested system. The results imply that wear analysis using numerical simulations aid the understanding of wear in machinery. The combined knowledge of physical conditions on different important scales enables in-depth analysis with numerical tools which cannot be achieved through experimental investigations alone. Furthermore, the numerical model can be refined leading to better wear predictions.
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| 9. |
- Furustig, Joel, et al.
(författare)
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A wear model for EHL contacts in gerotor type hydraulic motors
- 2015
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 229:2, s. 254-264
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Tidskriftsartikel (refereegranskat)abstract
- The heart of gerotor motors is a gear-set. The gear-set consists of an inner gear which is rotating and orbiting in contact with an outer gear. Wear in these contacts is investigated experimentally and with a numerical implementation of an Archard based wear model in combination with a load sharing concept. The model utilizes the symmetry of the motor and is based on a three-scale approach to estimate the wear on the gears. The global model calculates contact forces, relative surface velocities and contact radii in the contacts between inner and outer gear. The calculations performed on the local scale are used to collect information about the influence of the surface roughness on lubricant film thickness. The wear depth is calculated on a semi-local scale, involving only one tooth on the outer gear. In partial elastohydrodynamic lubrication, load is carried by the part of the conjunction where there is direct contact between the mating surfaces and by the lubricant pressure. In the wear model, wear only occurs as a direct consequence of contact between the mating surfaces. Experimental results are compared with the model predictions for equivalent running conditions. The wear predicted by the model agrees with the experimental results. For this reason, it is concluded that wear in the gerotor motor is dominated by the wear mechanisms which are considered in the tribological model.
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| 10. |
- Gopal, Dhivyasri, et al.
(författare)
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Optimization of processing parameters of cold metal transfer joined 316L and weld bead profile influenced by temperature distribution based on genetic algorithm
- 2022
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Ingår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science. - : Sage Publications. - 0954-4062 .- 2041-2983. ; 236:19
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Tidskriftsartikel (refereegranskat)abstract
- Austenitic stainless steel alloys find the wide range of application in modern industries like pipework, containers, food production and in medical industries for its excellent processing properties and corrosion resistance. There is enormous literature report on the mechanical properties, appropriate joining of materials using different fusion welding processes. Consequently, the cold metal transfer technique appears to weld materials with low heat input which is a noticeable feature of this welding process. In this paper, cold metal transfer welding is performed on austenitic stainless steel material 316L and its bead geometries such as reinforcement height, depth of weld penetration and bead width profile are examined. The temperature distribution at the welding line is observed by means of the data acquisition unit. Genetic algorithm based optimization technique is used to achieve the desired combination of input variables and weld bead geometry. This developed genetic algorithm optimizes the welding process parameters and geometry of the weld bead, by minimizing the least square error based objective function. The investigation outcome of this paper provides an insight into the characterization of the weldment, the effects of weld current and weld travel speed on temperature profile and mechanical properties include hardness, tensile and residual profiles.
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