Steel, elastic moduli

Example 10 Response to Instantaneous Valve Closing Compute the wave speed and maximum pressure rise for instantaneous valve closing, with an initial velocity of 2,0 m/s, in a 4-in Schedule 40 steel pipe with elastic modulus 207 X 10 Pa, Repeat for a plastic pipe of the same dimensions, with E = 1.4 X 10 Pa. The liquid is water with P = 2.2 X 10 Pa and p = 1,000 kg/m. For the steel pipe, D = 102,3 mm, b = 6,02 mm, and the wave speed is... 

Elastic modulus Up to the fracture stress, glass behaves, for most practical purposes, as an elastic solid at ordinary temperatures. Most silicate-based commercial glasses display an elastic modulus of about 70GNm", i.e. about 1/3 the value for steel. If stress is applied at temperatures near the annealing range, then delayed elastic effects will be observed and viscous flow may lead to permanent deformation. 

To compare with experimental results, the parameters corresponding to real conditions were used in our computation cases. The lubricant used in the experiment is polyglycol oil. The diameter of the steel ball is 25.4 mm, elastic modulus of the balls is 2.058 X 10 Pa, and the elastic modulus of the glass disk is 5.488 X 10 ° Pa. The circumstance temperature is 28 1 °C. The oil viscosity-pressure index is taken as 1.5 X10- Pa-. ... 

The tensile strength and elastic modulus of metals decrease with increasing temperature. For example, the tensile strength of mild steel (low carbon steel, C < 0.25 per cent) is 450 N/mm1 2 3 4 at 25°C falling to 210 at 500°C, and the value of Young s modulus... 

For steel, the modulus of elasticity is the same in the elastic region and yield plateau for static and dynamic response. In the strain hardening region the slope of the stress-strain curve is different for static and dynamic response, although this difference is not important for most structural design applications. 

In summary, we can first say that there is no significant evidence that the low surface energy siloxane-modified epoxies reduce friction compared with the unmodified epoxy or the ATBN- and CTBN-modified epoxies. Based on the results of the steel ball-on-epoxy experiments, the most significant effect of the siloxane modifiers is the reduction of the elastic modulus associated with large closely spaced domains. The longer initiation times and lowest wear rates observed for the siloxane-modified epoxies were generally associated with a lower modulus. Epoxy modified with the CTBN of 18% AN content also showed lower wear rates with lower modulus but, in contrast with the siloxane-modified resins, had shorter initiation times with lower modulus. 

Suzuki et al ° made hot-pressed composites of molybdenum disulphide 80%, molybdenum dioxide 10% and niobium 10%. They were pressed at 25 MPa and 1500°C in carbon dies, and the flexural strength was 59 - 63 MPa and the elastic modulus 27.9 MPa. To improve the strength they added 5% of 304 stainless steel, and this gave a flexural strength of 69 - 80 MPa and elastic modulus 43.8 MPa. The coefficient of friction of the latter compact was 0.07 to 0.18 and the specific wear rate 2.2 x 10" mm Nm at 450°C in vacuum. 

Implant materials for coating. Prosthetic materials coated with HAp include titanium, Ti-6A1-4V, stainless steel, Co-Cr-Mo, and alumina (Jiang and Shi 1998). These materials are roughened by grit blasting for a mechanical interlock between the melted component of the particle and the substrate. The Ti-6A1-4V and Cr-Co-Mo alloys are the most common. Ideally, the elastic modulus and co-efficient of thermal expansion of the substrate and the coating material will be matched to minimize any residual stresses at the interface. Hydroxylapatite (E = 100 GPa and a = 12 x 10 °C (Perdok et al. 1987)) is... 

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