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1

Dilatant-fluid torsional vibration damper for a four-stroke diesel engine crankshaf

Kozytskyi Sergiy, Kiriian Sergii

Polish Maritime Research

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2023

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nr 1

121--125

EN

This paper presents a study of a viscous torsional vibration damper for a crankshaft of a four-stroke diesel engine. The reliable operation of a widely used silicone-type viscous damper depends on the ability of the silicone oil to absorb the energy of torsional vibrations. The non-Newtonian shear flow of the silicone oil interlayer, characterised by a reduction in the shear-rate-dependent viscosity and a moment of the drag forces, negatively affects damping characteristics. A torsional vibration damper, filled with a shear-thickening fluid, was considered and a rheological approach, based on viscosity growth with the shear rate increase, was applied. For such a damper, larger velocity gradients correspond to the higher values of a viscous force, which decreases torsional vibration. The parameter of damper effectiveness (defined by the fluid flow index, values of the damper gaps, torsional vibration amplitude and frequency) was implemented. It has been established that the efficiency of the torsional vibration damper filled with a dilatant fluid does not depend on the damper dimensions and gaps and significantly increases when a shear-thickening fluid is used instead of silicone oil or a Newtonian fluid. At higher values of the flow index, when the non-Newtonian flow becomes distinct, torsional vibrations are damped more effectively. Critical vibration amplitudes at high-velocity gradients, in turn, increase the damping effect as the moment of the drag forces and flow index are power-law related.

2

Employment of concentrated-hardsphere-suspension pad for V-bending of thin strip

Ohashi T., Chiba H., Takano H.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 2

699-704

EN

Purpose: Authors have suggested employment of dilatant fluid for metal forming tools, and report an application on v-bending of thin stainless steel strips in this paper. Design/methodology/approach: An alumina concentrated hard-sphere suspension is employed as dilatant fluid for forming. The authors evaluate the suspension with backward extrusion test. Then, the authors try to bend SUS304 stainless strip with 0.25 mm thickness and 30 mm width on the pad of the suspension with a v-bend punch. Findings: Behaviour of the suspension is revealed in backward extrusion test. Migration of water takes important role in it. In v-bending test, including acute angle bending, the authors bend the strip with only the v-bend punch and the alumina concentrated hard-sphere suspension pad successfully. It is thought that forming load is less than with general polyurethane tools. Research limitations/implications: Spring-back in partial bending, which is similar to the suggested process, is larger than in bottoming and coining with dies and bending with polyurethane tools. Therefore, the authors are going to evaluate the spring-back in the suggested process in further study. Practical implications: Polyurethane pad is used in bending process generally because of advantageous points in easy-design, and safe from scratch. However it has disadvantageous points in its limited life and necessity of large forming load. The alumina concentrated hard-sphere suspension can be employed for such the pad with unlimited life. In addition, such the dilatant fluid can be applied on other metal forming process as easy tool. Originality/value: Employing dilatant fluid for forming tools is new idea. Authors try v-bending with an alumina concentrated hard-sphere suspension.

3

Employment of alumina suspension pad for v-bending of SUS304 strip

Ohashi T., Chiba H., Takano H.

Archives of Materials Science and Engineering

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2008

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Vol. 30, nr 1

57-60

EN

Purpose: Authors have suggested employment of dilatant fluid for metal forming tools, and report an application on v-bending of thin stainless steel strips in this paper. Design/methodology/approach: An alumina concentrated hard-sphere suspension is employed as dilatant fluid for forming. The authors evaluated the suspension with backward extrusion test. Followed by SUS304 stainless strip with 0.25mm thickness and 30mm width on the pad of the suspension with a v-bend punch. Findings: Behaviour of the suspension is revealed in the backward extrusion test. Migration of water takes important role in it. In v-bending test, including acute angle bending, the authors bend the strip with only the vbend punch and the alumina concentrated hard-sphere suspension pad successfully. It is thought that forming load is less than with general polyurethane tools. Research limitations/implications: Spring-back in partial bending, which is similar to the suggested process, is larger than in bottoming and coining with dies and bending with polyurethane tools. Therefore, the authors will evaluate the spring-back in the suggested process in further study. Practical implications: Polyurethane pad is used in bending process generally because of advantageous points in easy-design, and safe from scratch. However it has disadvantageous points in its limited life and necessity of large forming load. The alumina concentrated hard-sphere suspension can be employed for such a pad with unlimited life. In addition, such dilatant fluid can be applied on other metal forming process as easy tool. Originality/value: Employing dilatant fluid for forming tools is new idea. V-bending with an alumina concentrated hard-sphere suspension was attempted.

4

Natural convection of power-law fluid

Uściłowska A., Stręk T.

Vibrations in Physical Systems

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2004

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Vol. 21

399--402