Time filter

Source Type

Mildenhall, United Kingdom

DTR VMS Ltd | Date: 2013-07-12

A hydraulically damped mounting device (

DTR VMS Ltd | Date: 2010-08-25

A hydraulically damped mounting device has first and second anchor parts connected by a first deformable wall, and a working chamber for hydraulic fluid partially bounded by the first deformable wall. The working chamber is connected to a composition chamber for the hydraulic fluid by a first passageway, the composition chamber being partially bounded by a second deformable wall. There is also an auxiliary chamber partially bounded by a third deformable wall connected to the working chamber by a second passageway. The mounting device then has a vacuum chamber connectable to a vacuum source for varying the pressure in the vacuum chamber.

DTR VMS Ltd and Avon Vibration Management Systems Ltd | Date: 2004-08-17


Saeed F.,University of Engineering and Technology Lahore | Ansarifar A.,Loughborough University | Ellis R.J.,DTR VMS Ltd | Haile-Meskel Y.,DTR VMS Ltd
Journal of Rubber Research | Year: 2013

Rubber is viscoelastic in nature and used in a variety of industrial applications. Rubber mounts are used to dampen vibration and shock. Damping, fatigue and dynamic properties of rubber mounts depend to a large extent on chemical ingredients mixed with the rubber. Natural rubber is the most widely used polymer for conventional mounts. Apart from natural rubber, different fillers and rubber chemicals are also present in conventional formulation of rubber mounts. Conventionally, five different classes of chemical curatives are used in rubber industries, which include curing agents, primary and secondary accelerators as well as primary and secondary activators. When chemical curatives are present in excessive amounts in rubber, they migrate to the rubber surface and form a bloomed layer. In this work, two rubber formulations were used for preparing rubber-to-metal bonded bobbin mounts. The formulations were primarily based on natural rubber with 60 parts per hundred rubber by weight (p.h.r.) precipitated amorphous white silica nanofiller. The surface of silica was pre-treated with bis(3-triethoxysilylpropyl)-tetrasulphane (TESPT) coupling agent to chemically bond silica to the rubber. The rubber was cured primarily by reacting the tetrasulphane groups of TESPT with the rubber chains using a sulphenamide accelerator and the cure was then optimised by adding zinc oxide as an activator. The ratio of the accelerator to activator in one compound was 6 p. h.r./0.3. p.h.r. and the compound showed extensive blooming of the accelerator on the rubber surface when stored at ambient temperature for up to 60 days. However, the blooming was reduced significantly by changing the ratio of the accelerator to activator to 3 p.h.r./2.5. p.h.r., which was subsequently used to prepare a second compound. Dynamic and static properties of the bobbins were subsequently measured. Both compounds showed very low phase angle (δ) and spring rate ratio Kd/Ks (Kd: dynamic spring rate; Ks: static spring rate). Notably, the compound with the high accelerator to activator ratio had superior aforementioned properties, but the dynamic fatigue life of the bobbin reduced noticeably due to a gradual deterioration of the bond caused by the migration of the accelerator to the bonded interface. Source

Saeed F.,Loughborough University | Ansarifar A.,Loughborough University | Ellis R.J.,DTR VMS Ltd | Haile-Meskel Y.,DTR VMS Ltd
Journal of Applied Polymer Science | Year: 2012

Two rubber compounds with different amounts of chemical curatives were prepared by mixing natural rubber with a high loading of a sulfur-bearing silanized precipitated amorphous white silica nanofiller. The chemical bonding between the filler and rubber was optimized via the tetrasulfane groups of the silane by adding a sulfenamide accelerator and zinc oxide. The rubber compounds were cured and stored at ambient temperature for 65 days before they were tested. One compound showed extensive blooming as a function of storage time. Thin tensile strips of the rubber vulcanizates containing an edge crack were repeatedly stressed at constant strain amplitude and test frequency at ambient temperature and crack length c was measured as a function of the number of cycles n. The cut growth per cycle, dc/dn, was calculated and plotted against the tearing energy, T. The blooming of the chemical curatives increased dc/dn by up to an order of magnitude at a constant T. This was due to the reagglomeration of the chemical curatives in the rubber and also within a thin layer approximately 15 to μm in size beneath the rubber surface. Under repeated stressing, cracks grew through the relatively weak agglomerated areas in the rubber and this caused the rate of crack growth to increase at a constant T. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012. Source

Discover hidden collaborations