The studies considered the impacts of brake pad shape, instantaneous angular velocity, radial position, and so forth but did not include the impact of the shape and structural layout of brake pad friction blocks upon brake disc temperature and stress.
The structure differences of friction blocks of a brake pad can lead directly to differences in friction contact time and friction speed at each point on the brake disc surface, result in uneven temperature distribution on the brake disc surface, consequently cause high thermal stress, and therefore exacerbate the brake disc thermal fatigue.
Starting from the relations between the friction block structural difference of the brake pad and the temperature and stress fields of brake disc, this paper establishes a connection between friction block structures of brake pad and temperature and stress distribution characteristics of brake disc, optimizes the structure and arrangement of the brake pad friction blocks, analyzes the variation of brake disc temperature and stress with the optimized brake pad, and finally validates the findings by sequential coupling simulations with ABAQUS6.8 finite element software.
(v) the physical properties of the friction blocks do not change with temperature in the braking process.
Refer to Table 1 for related parameters of brake disc and friction blocks. Brake disc is made of 28CrMoV5-08, and brake pad is made of copper base powder metallurgy materials.
For brake disc A1, the friction blocks are distributed more evenly on its surface, the overlaying of friction heat decreases, and the brake disc surface temperature and stress are the lowest.
Three circular friction blocks of the same radius are located arbitrarily on the disc friction surface which is divided into seven equal distance rings of equal radial distance (or the ring thickness) H of 17.22 mm.
For the impact of brake pad structure on the friction heat distribution on the brake disc in circumferential direction, we adopt the circumferential structural factor, which is defined as the ratio of clearance area [S.sub.c] between friction blocks to total area [S.sub.t] of friction contact area of friction blocks multiplied by m, the number of friction blocks on the same friction ring:
Table 8 is the A1 data of optimized brake pad structure of 5 friction blocks, in which r is the friction ring radius of friction block center on the brake disc and (9 is the circumferential angle (Figure 9) of friction block center on the brake disc.
Due to the advancement in computer software, studies of existing hydraulic structures with appurtenants such as gates, baffle and friction blocks become possible.
Energy Dissipation System at Taunsa Barrage: Taunsa barrage energy dissipation system consisted of 77 ft long stilling basin, two rows of baffle/impact blocks and two rows of friction blocks (Chaudhry 2009).