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  • 1.
    Aidanpää, Jan-Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Review of Mechanical Vibrations by S.S. Rao2007Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 221, nr 1, s. 135-Artikkel i tidsskrift (Annet vitenskapelig)
  • 2.
    Calleecharan, Yogeshwarsing
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Aidanpää, Jan-Olov
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Dynamics of a hydropower generator subjected to unbalanced magnetic pull2011Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 225, nr 9, s. 2076-2088Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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

  • 3.
    Furustig, Joel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Almqvist, Andreas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Pelcastre, Leonardo
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Bates, Charles Anthony
    Danfoss Power Solutions ApS, Nordborg.
    Ennemark, Poul
    Danfoss Power Solutions ApS, Nordborg.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    A strategy for wear analysis using numerical and experimental tools, applied to orbital type hydraulic motors2016Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 230, nr 12, s. 2086-2097Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 4.
    Furustig, Joel
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Almqvist, Andreas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Bates, C.A.
    Danfoss Power Solutions ApS, Nordborg.
    Ennermark, P.
    Danfoss Power Solutions ApS, Nordborg.
    A wear model for EHL contacts in gerotor type hydraulic motors2015Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 229, nr 2, s. 254-264Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 5. Grapis, O.
    et al.
    Ohlson, Nils-Gunnar
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Andersons, J.
    Rotor-frame contact in a centrifuge installed on board a ship2010Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 224, nr C3, s. 635-646Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The criticality of rotor and stator contact in a large-size marine separator is studied by numerical modelling. Two plausible mechanisms leading to such contact, namely rolling of a ship in steady-state motion and a suddenly occurring unbalance in the rotor, are considered. It is found that contact due to sea motion may be tolerable, while sudden development of unbalance at operating speed can lead to unacceptably high contact forces. This agrees with experience of centrifugal separators operating on board of ships.

  • 6. Hosseini-Hashemi, Sh.
    et al.
    Atashipour, Seyed Rasoul
    Fadaee, M.
    On the buckling analysis of isotropic, transversely isotropic and laminated rectangular plates via Reddy plate theory: an exact closed-form procedure2012Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 226, nr 5, s. 1210-1224Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Based on Reddy's third-order shear deformation theory, an exact closed-form solution is proposed to describe linear buckling of transversely isotropic laminated rectangular plates under either mono- or bi-axial compressive in-plane loads. To this end, the coupled governing equations are exactly converted to two sets of uncoupled equations for in-plane and transverse deformations of symmetric laminated plates. The new uncoupled equations are analytically solved by applying both Navier and Lévy-type solution methods. The validity and high accuracy of the current exact solution are evaluated by comparing the present results with their counterparts reported in literature.

  • 7.
    Lindholm, Per
    et al.
    KTH.
    Sosa, Mario
    KTH.
    Olofsson, Ulf
    KTH.
    The effect of elasticity in powder metal gears on tooth loading and mean coefficient of friction2018Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 232, nr 11, s. 2023-2031Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Powder metal gears have a lower density than conventional steel gears due to their intrinsic porosity from the manufacturing process. This also results in a lower elasticity leading to larger deformations and lower contact pressure in a gear contact. By using different modelling tools (namely FEA and available commercial software), the load behavior along the line of action is studied to compare the influence of lower elasticity with standard wrought steel elasticity for FZG-C type gears. A further step is taken analyzing this effect on the mean coefficient of friction through the recalculation of the gear mesh power loss factor. Conclusions observed are differences in load distribution and marginal differences in the gear mesh power loss factor when comparing sintered and wrought steel FZG-C type gears. Sintered steel showed a marginally longer line of action and simultaneously a decrease of the single tooth contact length when compared to wrought steel, while differences in the gear mesh power loss factor proved non-essential due to the spread in previously measured experimental data.

  • 8.
    Pérez-Ràfols, Francesc
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Larsson, Roland
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    van Riet, Egbert J.
    Shell Global Solutions International BV, Innovation, Research and Development.
    Almqvist, Andreas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    On the flow through plastically deformed surfaces under unloading: A spectral approach2018Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 232, nr 5, s. 908-918Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study considers flow through the gap left between two surfaces during unloading, in other words, when an applied load is gradually reduced after loading to a state where plastic deformation occurs. In particular, the permeability of the gap is studied. It was found that a substantial reduction of the applied load is required before the permeability starts to increase significantly. The explanation for this phenomenon is given by the combination of components with different wavelengths present in the surface. Components with long wavelengths deform elastically and those with shorter wavelengths may also deform plastically. We found that plastic deformation acts to keep the permeability nearly constant at the beginning of the unloading and elastic spring-back is responsible for the rapid increase at lower loads. This principle constitutes a basis for the strategy that was developed in order to predict the load at which the rapid increase of permeability starts.

  • 9. Saidi, A.R.
    et al.
    Atashipour, Seyed Rasoul
    Keshavarzi, H.
    Bending analysis of thick laminated rectangular plates using a boundary layer function2010Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 224, nr 10, s. 2073-2081Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, the governing bending equations of thick laminated transversely isotropic rectangular plates are derived based on third-order shear deformation theory (TSDT). Using a new function, called the boundary layer function, the three coupled governing equations are converted to two decoupled equations. These equations are in terms of the deflection of the plate and the mentioned boundary layer function, which are written in invariant form. By solving the decoupled equations, a Levy-type analytical solution is presented for bending of a transversely isotropic plate. Finally, numerical results are presented for boundary layer phenomenon and its effects in TSDT. It is shown that all of the boundary layer effects in Mindlin—Reissner theory appear in this theory. However, it is shown that the intensity of the boundary layer effects in TSDT exceeds that of the Mindlin—Reissner theory.

  • 10.
    Sun, Tao
    et al.
    Tianjin University.
    Wu, Hao
    Lian, Binbin
    Yang, Qi
    Wang, Panfeng
    Stiffness modeling, analysis andevaluation of a 5 degree of freedom hybrid manipulator for friction stirwelding2017Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 231, s. 4441-4456Artikkel i tidsskrift (Fagfellevurdert)
  • 11.
    Thomas, Tom
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Rosén, Bengt-Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Maskinteknisk produktframtagning (MTEK), Funktionella ytor.
    Implementation of Whitehouse's method for calculating properties of self-affine fractal profiles2008Inngår i: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 222, nr 8, s. 1547-1550Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many software packages for roughness analysis offer the possibility of calculating the fractal dimension D of surface profiles by techniques, which assume them to be self-similar and therefore uniquely defined by D. However, fractal profiles are not self-similar but self-affine, so that two profiles of quite different roughnesses may share the same fractal dimension. To distinguish between them requires the calculation of an additional scaling factor, the so-called topothesy Λ. Traditionally, D and Λ are derived laboriously from the slope and intercept of the profile's structure function. A quicker and more convenient derivation from standard roughness parameters has been suggested by Whitehouse. Based on this derivation, it is here shown that D and Λ depend on two dimensionless numbers: the ratio of the mean peak spacing to the rms roughness and the ratio of the mean local peak spacing to the sampling interval. Using this approach, values of D and Λ are calculated from the measurements on surface profiles produced by polishing, plateau honing, and various single-point machining processes. Different processes are shown to occupy different regions in D-Λ space, and polisbed surfaces show a relationship between D and Λ, which is independent of the surface material. © IMechE 2008.

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