scholarly journals Thermo-Mechanical Coupling Analyses for Al Alloy Brake Discs with Al2O3-SiC(3D)/Al Alloy Composite Wear-Resisting Surface Layer for High-Speed Trains

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3155
Author(s):  
Lan Jiang ◽  
Yanli Jiang ◽  
Liang Yu ◽  
Hongliang Yang ◽  
Zishen Li ◽  
...  
Keyword(s):  
Surface Layer ◽  
Thermal Stress ◽  
Transient Temperature ◽  
Al Alloy ◽  
Brake Disc ◽  
Air Cooling ◽  
Alloy Composite ◽  
Maximum Friction ◽  
Brake Discs ◽  
Friction Temperature

In the present work, a theoretical model of three-dimensional (3D) transient temperature field for Al alloy brake discs with Al2O3-SiC(3D)/Al alloy wear-resisting surface layer was established. 3D transient thermo-stress coupling finite element (FE) and computational fluid dynamic (CFD) models of the brake discs was presented. The variation regularities of transient temperature and internal temperature gradient of the brake discs under different emergency braking conditions were obtained. The effects of initial braking velocity (IBV) and thickness of Al2O3-SiC(3D)/Al alloy composite wear-resisting layer on the maximum friction temperature evolution of the disc were discussed. The results indicated the lower temperature and thermal stress distributed uniformly on the wear-resisting surface, which was dominated by high conductivity and cooling ability of the Al alloy brake disc. The maximum friction temperature was not obviously affected by the thickness of the wear-resisting layer. The maximum friction temperature of the brake discs increased with the increase of the IBV, the maximum friction temperature and thermal stress of the brake discs is about 517 °C and 192 MPa at IBV = 97 m/s considering air cooling, respectively. The lower thermal stress and fewer thermal cracks are produced during the braking process, which relatively decrease the damage. The friction behavior of the tribo-couple predicted using FE method correlated well with the experimental results obtained by sub-scale testing.

Coupling Analysis of Frictional Heat under Control of Disc Brake Anti-Skid Brake System

2011 ◽  
Vol 199-200 ◽  
pp. 721-728
Author(s):  
Yi Bing Zhang ◽  
Ying Ying Zhang
Keyword(s):  
Thermal Stress ◽  
Friction Pair ◽  
Brake System ◽  
Frictional Heat ◽  
Brake Disc ◽  
Analysis Model ◽  
Element Analysis ◽  
Study Results ◽  
Friction Temperature ◽  
Braking Force

The nonlinearity of material properties at different temperatures and the manner of braking force applying on a brake system are two key factors to affect the coupling of temperature and thermal stress. Considering these two factors, a finite element analysis model of automobile brake disc and pad is established. By using the model, the dynamic frictional heat and thermal stress of braking friction pair could be simulated and the coupling characters of temperature and thermal stress on friction surfaces could be studied, where the braking force is constant or controlled by an anti-skid brake system(ABS). The study results shown that the friction temperature of brake disk rises in periodic and fluctuant tendency. The fluctuant increase of temperature will influence the character of braking. The increase of friction temperature between a brake disc and pad can decrease under the control of ABS, so the effect of thermo-mechanical coupling could be reduced.

FEM for Brake Discs of SiC 3D Continuous Ceramic Reinforced 7075 Aluminum Alloy for CRH3 Trains Applying Emergency Braking

2011 ◽  
Vol 120 ◽  
pp. 51-55 ◽  
Author(s):  
Liang Yu ◽  
Yan Li Jiang ◽  
Sen Kai Lu ◽  
Hong Qiang Ru ◽  
Ming Fang
Keyword(s):  
Aluminum Alloy ◽  
Thermal Stress ◽  
High Speed ◽  
Distribution Model ◽  
Transient Temperature ◽  
Brake Disc ◽  
Three Dimension ◽  
High Speed Train ◽  
Emergency Braking ◽  
Aluminum Alloy 7075

The shaft disc prepared with SiC 3D continuous ceramic frame reinforced aluminum alloy 7075 (3D-SiC/Al) composite of the CRH3 high speed train with a speed at 250 km/h was chosen as the research object, and the course of emergency brake was simulated by Cosmos. A three dimension model was established, the way of applying loads were discussed, and the temperature field and thermal stress field were obtained. The result shows that the highest temperature appears at about 57 s since braking and the value is about 373 °C. The biggest stress is about 237 MPa, appearing at about 51 s since braking, the regions distribute at the surface corresponding with the radiating ribs, and near the inner diameter. The hoop stress is larger than other directions. The result shows that the thermal stress duce to the transient temperature distribution model is released well for the distribution of the 3D continuous ceramic frame reinforced aluminum alloy 7075 structure compares with the conventional brake disc, which can satisfy the requirement of the shaft disc of the high speed train with a speed at 250 km/h applying emergency braking.

ANSYS Analysis on Thermal Structure of Bionic Brake Discs

2015 ◽  
Vol 789-790 ◽  
pp. 430-435
Author(s):  
Li Xin Wang ◽  
Ya Yan Gao ◽  
Li Qiang Peng ◽  
Li Gang Zhai
Keyword(s):  
Smooth Surface ◽  
Heat Dissipation ◽  
Thermal Structure ◽  
Field Analysis ◽  
Transient Temperature ◽  
Brake Disc ◽  
Brake Discs ◽  
Thermal Wear ◽  
Brake Performance ◽  
Braking Process

The failure of brake performance, which is caused by thermal recession under the emergency brake, results in traffic accident frequently. Based on excellent wear-resisting properties of locust’s non-smooth surface structure, bionic brake disc with special surface micro-structure was designed. According to the thermal analysis theory, transient temperature field analysis of the bionic brake disc during the braking process under different initial velocity was analyzed. The results showed that bionic brake disc has excellent heat dissipation ability, which is beneficial to improve the brake performance. The non-smooth surface can store air and dissipate heat, thus reducing the thermal fatigue and thermal wear caused by temperature rise. This research provides a theoretical basis for designing bionic brake discs with excellent heat dissipation performance.

scholarly journals Air jet cooling of brake discs

2008 ◽  
Vol 222 (6) ◽  
pp. 995-1004 ◽  
Author(s):  
O F P Lyons ◽  
D B Murray ◽  
A A Torrance
Keyword(s):  
Heat Transfer ◽  
Hot Spot ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Brake Disc ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Jet Cooling ◽  
Air Jet ◽  
Brake Discs

This paper reports on an investigation of a novel approach to the cooling of brake discs, based on the application of impinging air jets. This has the capacity to enhance the heat transfer coefficients at the disc surface quite considerably without affecting the disc design, so that the disc construction may then be optimized without reference to heat transfer. Using a purpose built test-rig, disc temperature histories were recorded using infrared thermography for varying jet air flowrates, angle of impingement, dimensionless distance from the brake disc, and rotational speed. As well as comparing cooling effectiveness for different test parameters, convective heat transfer coefficients were calculated from the transient temperature data and were used as boundary conditions for a finite-element model of the process. The results obtained from this investigation suggest that the higher convection coefficients achieved with jet cooling will not only reduce the maximum temperature in the braking cycle but will reduce thermal gradients, since heat will be removed faster from hotter parts of the disc. Jet cooling should, therefore, be effective to reduce the risk of hot spot formation and associated disc distortion.

scholarly journals Evidence of Martensitic Transformation in Fe-Mn-Al Steel Similar to Maraging Steel

2020 ◽  
Vol 52 (1) ◽  
pp. 26-33
Author(s):  
Gurumayum Robert Kenedy ◽  
Yi-Jyun Lin ◽  
Wei-Chun Cheng
Keyword(s):  
Martensitic Transformation ◽  
Maraging Steel ◽  
Trip Steel ◽  
Single Phase ◽  
Lath Martensite ◽  
Al Alloy ◽  
Air Cooling ◽  
Small Temperature Gradient ◽  
Austenite Grains ◽  
Equilibrium Phases

AbstractThe Fe-Mn-Al steels claim a low density, and some fall into the category of transformation-induced plasticity (TRIP) steel. In Fe-Mn-Al TRIP steel development, phase transformations play an important role. Herein, the martensitic transformation of an Fe-16.7 Mn-3.4 Al ternary alloy (wt pct) was experimentally discovered, whose equilibrium phases are a single phase of austenite at 1373 K and dual phases of ferrite and austenite at low temperature. Ferritic lath martensite forms in the prior austenite grains after cooling from 1373 K under various cooling rates via quenching, air cooling, and furnace cooling. The formation mechanism of the ferritic lath martensite is different from that of traditional ferritic lath martensite in steel and quite similar to that in maraging steel. A slight strain energy coupled with a small temperature gradient can lead to the formation of ferritic lath martensite in the Fe-Mn-Al alloy after cooling from high temperature. It is also found that micro-twins exist in the ferritic lath martensite.

scholarly journals Precipitation during Quenching in 2A97 Aluminum Alloy and the Influences from Grain Structure

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2802
Author(s):  
Xiaoya Wang ◽  
Jiantang Jiang ◽  
Guoai Li ◽  
Wenzhu Shao ◽  
Liang Zhen
Keyword(s):  
Aluminum Alloy ◽  
Grain Structure ◽  
Water Quenching ◽  
Al Alloy ◽  
Air Cooling ◽  
Quenching Rate ◽  
Subsequent Aging ◽  
Nucleation Sites ◽  
Aging Response ◽  
Δ Phase

The quench-induced precipitation and subsequent aging response in 2A97 aluminum alloy was investigated based on the systematic microstructure characterization. Specifically, the influence on precipitation from grain structure was examined. The results indicated the evident influence from the cooling rate of the quenching process. Precipitation of T1 and δ′ phase can hardly occur in the specimen exposed to water quenching while become noticeable in the case of air cooling. The yield strength of 2A97-T6 alloy de-graded by 234 MPa along with a comparable elongation when water quenching was replaced by air cooling. Sub-grains exhibited a much higher sensitivity to the precipitation during quenching. The presence of dislocations in sub-grains promoted the quench-induced precipitation by acting as nucleation sites and enhancing the diffusion of the solute. A quenching rate of 3 °C/s is tolerable for recrystallized grains in 2A97 Al alloy but is inadequate for sub-grains to inhibit precipitation. The study fosters the feasibility of alleviating quench-induced precipitation through cultivating the recrystallization structure in highly alloyed Al–Cu–Li alloys.

Study of Microstructure Evolution during Semi-Solid Processing of an In-Situ Al Alloy Composite

2015 ◽  
Vol 30 (3) ◽  
pp. 356-366 ◽  
Author(s):  
Santosh Kumar ◽  
Prosenjit Das ◽  
Sandeep K. Tiwari ◽  
Manas K. Mondal ◽  
Supriya Bera ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Al Alloy ◽  
Alloy Composite ◽  
Semi Solid

scholarly journals The Electrical Resistivity of a SiCw/Al Alloy Composite with Temperature

2004 ◽  
Vol 14 (7) ◽  
pp. 489-493
Author(s):  
Byung-Geol Kim ◽  
Shang-Li Dong ◽  
Su-Dong Park ◽  
Hee-Woong Lee
Keyword(s):  
Electrical Resistivity ◽  
Al Alloy ◽  
Alloy Composite
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