R&D Journal最新文献

{"title":"Statistical Analysis of Effects on Weld Response Variables during Friction Hydro-Pillar Processing","authors":"C. V. Zyl, D. Hattingh","doi":"10.17159/2309-8988/2019/v35a2","DOIUrl":"https://doi.org/10.17159/2309-8988/2019/v35a2","url":null,"abstract":"R & D Journal of the South African Institution of Mechanical Engineering 2019, 35, 9-20 http://dx.doi.org/10.17159/2309-8988/2019/v35a2 http://www.saimeche.org.za (open access) © SAIMechE All rights reserved. 9 Abstract: The article provides insight to the complex relationships that exist between the selected weld process parameters and the associated effects on weld responses by application of statistical analysis relating to response predictive models for Friction Hydro-Pillar Processing (FHPP). The literature review focused at obtaining the current assumptions made with regards to the relationship between FHPP and conventional Friction Welding (FW) variations. Experimental welds were produced at varying selected process parameters; motor speed, axial force, consumed length and forging time. These parameters were compared to five weld response variables through a 27-run full factorial Design of Experiment and multiple regressions. The analysis focussed on quantifying the main effects of process parameters on energy input, temperature profile, friction time, torque and consumed rate. Comparison with experimental results served to validate the effect of dominant process parameters. The process and statistical analysis are explained in detail to assist further understanding of the applied methodology and the effect of the various process parameters on weld responses presented. Results indicate that the mathematical equation based models predict the responses adequately within the limits of welding parameters used and that no single parameter solely control the weld responses during FHPP. This study provides a clearer understanding of FHPP showing that generalised conclusions, with regards to the influences of process parameters on weld responses during conventional FW, cannot be made as the effects of these inputs differ depending on the combination of levels included in a parameter set.","PeriodicalId":299970,"journal":{"name":"R&D Journal","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123968753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fatigue Life Testing of Locally Additive Manufactured AlSilOMg Test Specimens","authors":"N. Agenbag, C. McDuling","doi":"10.17159/2309-8988/2019/V37A3","DOIUrl":"https://doi.org/10.17159/2309-8988/2019/V37A3","url":null,"abstract":"ABSTRACT In order for additive manufacturing to become a viable manufacturing methodfor aerospace engineering, it is required that exhaustive static and fatigue testing be performed. The testing is required in order to describe material properties in a statistical manner. Fatigue tests were performed on standard additive manufactured ASTM E466 test specimens in order to obtain the low (1000 cycles) to high cycle (1E6 cycles) behaviour of AlSi10Mg. The specimens were manufactured using non-heat treated, but stress relieved specimens. Specimens were printed in three build directions, namely the XY (parallel with build plate), 45 degree and vertical direction as measured with respect to the build baseplate. The three different directions were chosen to investigate the sensitivity of the material properties to the build direction. The specimens were stress relieved on the baseplate. Static testing was also performed on specimens according to ASTM E8/E8M. The specimens were produced to have a surface finish representative of standard deburring techniques used in the aerospace industry. The surface roughness on the specimens were measured. The scatter in test data as a result of the surface finish on material properties is quantified. It is a requirement to quantify the effect of the surface roughness on fatigue failure allowable values since a machined type finish (less than 3.2 micrometer) is not always practically possible to achieve with additive manufactured structures. This is because the organic shapes produced with additive manufacturing makes some surfaces inaccessible to normal surface finishing techniques. Furthermore, some internal structures such as lattice structures are completely inaccessible to surface finishing techniques such as polishing or lapping. In addition to the surface roughness the roundness of the test section was also measured using inspection equipment. This was required since the industrial deburring techniques did not yield a completely concentric test section as a lathe operation would produce. Once again this is representative of an additive manufactured structure. The fatigue tests were performed at an R-ratio of 0.1. The test results were used to produce Wöhler or S-N curves for the material in all three material directions. The scatter was quantified using industry accepted methods. The results were compared with fatigue test results from literature of specimens produced with a lathe in order to compare a practical industrial surface finish on an additive manufactured component with a machined surface finish. It was found that the build support structures of the additive manufacturing process causes stress concentrations in the fatigue test specimens. This leads to a reduction in fatigue life and an increase in the scatter of the results. Additional keywords: Additive manufacturing, fatigue testing, static testing, aluminium, AlSi10Mg.","PeriodicalId":299970,"journal":{"name":"R&D Journal","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122021073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Structural Design of a High-Performance WBD Brake Disc","authors":"A. Chen, K. Kang, F. Kienhöfer","doi":"10.17159/2309-8988/2021/v37a8","DOIUrl":"https://doi.org/10.17159/2309-8988/2021/v37a8","url":null,"abstract":"ABSTRACT A high performance, newly-developed wire-woven bulk diamond (WBD) ventilated brake disc is introduced to reduce the operating temperatures and mass of conventional brake discs. The use of the highly porous material requires a deeper understanding of the mechanical stresses developed within a brake disc to be developed to improve the disc core strength to withstand the high stresses developed during braking. In this study, experimentally determined solid brake disc stress distribution results, separated into the compressive stresses due to the pad clamping force and the shear stresses due to the applied brake torque, were applied to the reinforcement ofthe WBD core brake disc. The analysis was based on the maximum predicted deceleration conditions of a medium sized truck (Mercedes-Benz Atego). While the WBD core material possessed sufficient strength to withstand the shearing due to the braking torque, the pad clamping load was predicted to cause disc failure. Consequently, straight radial ribs were designed to reinforce the ventilated core, with final rib dimensions of 74x14x2.5 mm, manufactured from mild steel (SAE1006). A total of 10 ribs at 36° intervals were added to reinforce the core, increasing the mass by 0.20 kg compared to the original disc. The newly reinforced WBD brake disc remains lighter than a commercially available pin-finned disc, and is expected to maintain superior thermal performance while possessing the required mechanical strength. Additional keywords: Ventilated disc, mechanical stresses, braking, stress distribution","PeriodicalId":299970,"journal":{"name":"R&D Journal","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124760987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bagasse-Based Desiccant Wheel Dehumidifier","authors":"H. Ramchurreetoo, B. Rajkumarsingh","doi":"10.17159/2309-8988/2019/v35a4","DOIUrl":"https://doi.org/10.17159/2309-8988/2019/v35a4","url":null,"abstract":"R & D Journal of the South African Institution of Mechanical Engineering 2019, 35, 31-37 http://dx.doi.org/10.17159/2309-8988/2019/v35a4 http://www.saimeche.org.za (open access) © SAIMechE All rights reserved. 31 Abstract: Green desiccants are obtained from natural waste products like bagasse. They are fully biodegradable and cause no harm to the environment compared to chemical desiccants. A bagasse-based desiccant wheel dehumidifier that uses a green desiccant like sugarcane bagasse to remove humidity from air has been implemented and tested. Sugarcane bagasse was chosen as the main desiccant since it not only shows high adsorption properties but is also abundant in Mauritius and is much cheaper compared to other desiccants. The prototype was implemented and tested under various input parameters. A mathematical model was constructed to show how the dehumidification rate varies with airflow, desiccant wheel speed and bagasse thickness. It was found that dehumidification rate increases with an increase of the previously mentioned parameters. Another finding showed that as dehumidification rate increases, a higher regeneration rate for the desiccant is required. At maximum operating conditions, the dehum idifier has a Coefficient of Performance of 0.0118 and a Moisture Removal Capacity of 2.06 g/min. It could also be deduced that at lower temperature, the prototype has a better efficiency. A controller was implemented and incorporated in the dehumidifier which responded well to different inlet air relative humidity and temperature.","PeriodicalId":299970,"journal":{"name":"R&D Journal","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124853918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Peridynamic Approach to Predict Ductile and Mixed-Mode Failure","authors":"J. H. Conradie, T. H. Becker, D. Z. Turner","doi":"10.17159/2309-8988/2019/V35A1","DOIUrl":"https://doi.org/10.17159/2309-8988/2019/V35A1","url":null,"abstract":": The peridynamic theory has been developed to address problems in solid mechanics regarding fracture through its integral non-local basis. It has been successful in predicting brittle cracking, however, uncertainty still remains with regards to mixed mode and ductile fracture. This work presents a study in using peridynamics to simulate fracture in mixed mode or ductile type fractures. The results are presented as a quantitative comparison between experimental tests and numerical simulations. Standard compact tension tests were performed on polymethyl methacrylate (PMMA), stainless steel 304L and aluminium 1200H4 to obtain the respective JR-curves and critical energy release rates,","PeriodicalId":299970,"journal":{"name":"R&D Journal","volume":"203 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125735111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drowsiness Detection using Android Application and Mobile Vision Face API","authors":"B. Rajkumarsingh, D. Totah","doi":"10.17159/2309-8988/2021/V37A4","DOIUrl":"https://doi.org/10.17159/2309-8988/2021/V37A4","url":null,"abstract":"ABSTRACT Absence of forbearance among drivers, fatigue and irresponsible behaviour among drivers result in countless fatal crashes and road traffic injuries. Driver drowsiness is a highly problematic issue which impairs judgment and decision making among drivers resulting in fatal motor crashes. This paper describes a simple drowsiness detection approach for a smartphone with Android application using Android Studio 3.6.1 and Mobile Vision API for drowsiness detection before and while driving. Physiological analysis and a quick facial analysis were performed to check drowsiness before the driver starts driving. The smartphone camera was used for analysing the heart rate by tracking colour changes due to blood flow on the fingertip. Facial analysis was undertaken by Google Vision API which determined the head position, blinking duration and yawning frequency through the eye opening and mouth opening probabilities. The heart rate, blinking duration, yawning frequency and speeding were used as indicators for drowsiness. The facial analysis was repeated with speeding data while driving with results analysed each one minute. A performance accuracy of the combined results with speeding detection proved to be around 93.3%. Additional keywords: Drowsiness detection; Facial analysis; Heartrate; Mobile Vision API; Physiological analysis.","PeriodicalId":299970,"journal":{"name":"R&D Journal","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129878060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}