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Externally Pressurized Thrust Spherical Bearing Performance Under Variable Lubricant Viscosity (Un-recessed Clearance Type)
Ahmad Waguih Yacout Elescandarany
Issue:
Volume 8, Issue 2, April 2020
Pages:
45-64
Received:
19 March 2020
Accepted:
7 April 2020
Published:
28 April 2020
Abstract: In a previous study handling this subject, a series of six papers has been published covering the fitted type (equal radii of this sort of bearings) with its configurations in details. The present study handles the same subject investigating the clearance type of this sort of bearings starting with the un-recessed one. The clearance type of bearings, where the sphere radius is smaller than that of the seat, provides plenty of complications and great divergence in its behavior compared with the fitted one. The study investigates theoretically the bearing behavior under the lubricant viscosity variation in the presence of the centripetal inertia due to the shaft rotation and the surface roughness. Solutions have been derived for the un-recessed clearance type of bearings with hemispherical and partial hemispherical seats in addition to its two special cases using capillary tube and orifice restrictors. Unlike other studies, using the conventional integration (i.e., without using the Sommerfeld substitution), only one equation with one form for the pressure gradient is derived to cover the positive and negative eccentricity ratios. Expressions for the pressure distribution, temperature distribution in turn the temperature rise, load carrying capacity; volume flow rate, frictional torque, friction factor, power losses and stiffness factor are obtained. The study shows the combined effects of the viscosity variation, the centripetal inertia and the surface roughness on the bearing performance. The optimum design (with constant viscosity) based on the minimum power losses, minimum flow rate and the optimal restrictor dimensions, in a previous study is checked where it is found out that designing this type of bearings on such basis only is not sufficient in despite of the bearing consistency. A natural dynamic phenomenon ignored in the previous study is revealed and briefly touched.
Abstract: In a previous study handling this subject, a series of six papers has been published covering the fitted type (equal radii of this sort of bearings) with its configurations in details. The present study handles the same subject investigating the clearance type of this sort of bearings starting with the un-recessed one. The clearance type of bearing...
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Bearing Box Process Specification and Tooling Design
Issue:
Volume 8, Issue 2, April 2020
Pages:
65-74
Received:
15 March 2020
Accepted:
31 March 2020
Published:
14 May 2020
Abstract: Reasonable process regulations and fixtures can ensure the high efficiency of parts processing and the economy of the enterprise. I started with data collection, then part analysis, then process design, then process specification design, and finally fixture design. In the process design, I obtained the best process route based on the experience of the production site to achieve the effect of saving time and increasing labor productivity. The design of the process specification was based on the production program, the production type was determined, and the process specification was compiled. Production, so the process card of parts and the card of machining process of parts were compiled. The fixture design is to design two sets of tools for the bearing box car mold and the bearing box drilling mold. The bearing box car mold is based on the processed large surface and the two right angle surfaces are used as positioning surfaces. The workpiece is fastened with bolts and nuts. The other large surface is up to size 70, φ180H7 holes; the bearing box drilling mold is based on the processed large surface, and is positioned at φ180H7 holes. The workpiece is fastened with bolts and nuts, and 6-φ13 holes are drilled to improve the part. Processing efficiency to ensure the quality of parts processing. In summary, the above-mentioned special fixture design scheme is adopted to ensure the production requirements of parts in batches and improve labor efficiency.
Abstract: Reasonable process regulations and fixtures can ensure the high efficiency of parts processing and the economy of the enterprise. I started with data collection, then part analysis, then process design, then process specification design, and finally fixture design. In the process design, I obtained the best process route based on the experience of ...
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Study on Optimization of Automobile Crash Box Considering the Influence of Strain Rate
Chih-Keng Chen,
Yu-Jie Ma
Issue:
Volume 8, Issue 2, April 2020
Pages:
75-80
Received:
20 April 2020
Published:
8 June 2020
Abstract: The strain rate is one of the main factors that determines the yield strength of the material, which has a great influence on the accuracy of the numerical simulation of the automobile crash box. The numerical simulation of the crash box considering the strain rate of the material is carried out, and found that the impact force on the longitudinal beam of the car body is large and the energy absorption ability is small during the collision process. Through two sets of optimization studies, the results show that increasing the double-sided convex groove at the proper position of the front crash box can effectively reduce the impact force transmitted to the car body at the initial stage of the collision, and at the same time reduce the energy absorption ability of the crash box; Adding double-sided grooves at the front crash box can make the crash box collapse smoothly, cut down the collision force transmitted to the car body, and increase the energy-absorbing ability. At the same time, the results of the two optimization designs are verified by the methods: the sense of crushing deformation and the average square of all nodes velocity.
Abstract: The strain rate is one of the main factors that determines the yield strength of the material, which has a great influence on the accuracy of the numerical simulation of the automobile crash box. The numerical simulation of the crash box considering the strain rate of the material is carried out, and found that the impact force on the longitudinal ...
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