Tuning of Friction Oscillation Amplitude in Halloysite, Montmorillonite, and Wollastonite Filled Friction Composites: Load, Speed, and Temperature Sensitivity

2021 ◽  
pp. 1-42
Author(s):  
Debarghya Saha ◽  
Bhabani K. Satapathy
Keyword(s):  
Operation Research ◽  
Oscillation Amplitude ◽  
Optimal Level ◽  
Research Approach ◽  
Composite Surface ◽  
Acceptable Range ◽  
Fe Content ◽  
The Coefficient Of Friction ◽  
Friction Oscillation ◽  
Frictional Oscillation

Abstract The influence of clay mineral silicate types, such as halloysite, montmorillonite, and wollastonite with tubular, plate like, and acicular morphologies respectively, on frictional oscillation of composite materials have been evaluated on Chase type dynamometer and optimised following the combination of Taguchi's L9 design of experiment and regression analysis approaches. The coefficient of friction of ~0.35-0.45 and cumulative wear at < 10 % remained well within the acceptable range. The optimal tuning of friction oscillation to reduce braking induced noise and vibration propensity has been achieved by montmorillonite clay with platelet type morphology or by combination of MgO and wollastonite clay with acicular morphology. The extent of Fe- content in wear debris close to ~ 80 % on the composite surface led to an optimal level of friction oscillation amplitude (Aamp). The hierarchical ranking of the clay based composites by TOPSIS based operation research approach lead to the understanding of design ideology optimization for composites to ensure minimal friction oscillations.

Kajian Kandungan Fe dalam Air Tanah Terhadap Kadar Ekskresi Yodium dalam Urin pada Anak Sekolah di Desa Cerme Kecamatan Panjatan Kabupaten Kulon Progo

2017 ◽  
Vol 19 (1) ◽  
pp. 7-11
Author(s):  
Vivi Linda Fristianti ◽  
Nur Hidayat ◽  
Slamet Iskandar
Keyword(s):  
Elementary School ◽  
Ground Water ◽  
School Children ◽  
Laboratory Data ◽  
Simple Random Sampling ◽  
Optimal Level ◽  
The Body ◽  
Design Data ◽  
Cross Sectional ◽  
Fe Content

Background : IDD problem is a serious problem, 33% of districts in Indonesia are endemic, 21% of endemic mild, moderate endemic 5% and 7% by weight endemic. Urine Iodine Excretion (EYU) illustrates the iodine intake of a person, because 90% of the iodine that enter the body are excreted through the urine. Blocking agents are substances certain minerals such as iron, manganese and calcium, which can bind iodine in groundwater. Objectives : This study aims to determine the relationship of Fe content in ground water sources against EYU levels in school children in the village of the District Cerme Panjatan Kulon Progo. Methods : An observational analytic research with cross sectional design. Data collection is done in May - June 2015. Location research Elementary School Cerme, District Panjatan Kulon Progo. The subjects of the study as many as 34 children in elementary school classroom Cerme 3, 4 and 5 were taken by simple random sampling. Well water and urine samples taken students then tested the iron in the Central Health Laboratory test Yogyakarta and iodine in urine in Magelang BP2GAKY Laboratory. Data analysis using Spearman Range test with significancy level : 0.05. Result : Fe content in the ground water is below the normal threshold is <0.3 mg / L. While levels EYU school children who are under the optimal level of 5.9%, the optimal level of 32.4%, and the optimum levels above 61.8% (optimal: 100 - 199μg / L). Conclusion : There was no significant relationship between the Fe content in groundwater with levels of EYU in school children in District Panjatan Kulon Progo (p = 0.447).   Keywords: Fe, EYU

scholarly journals A Model for Humanitarian Supply Chain: An Operation Research Approach

2018 ◽  
Vol 212 ◽  
pp. 659-666 ◽  
Author(s):  
Ma.Teodora E. Gutierrez ◽  
Jose Edgar S. Mutuc
Keyword(s):  
Supply Chain ◽  
Operation Research ◽  
Research Approach ◽  
Humanitarian Supply Chain

Effects of External Hard Particles on Brake Friction Characteristics During Hard Braking

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
M. K. Abdul Hamid ◽  
G. W. Stachowiak
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Contact Area ◽  
Oscillation Amplitude ◽  
Stopping Time ◽  
Hard Particle ◽  
Friction Coefficients ◽  
Hard Particles ◽  
Effective Contact ◽  
Friction Oscillation

The effects of external hard particles on the friction coefficients and its oscillation amplitudes during hard braking were investigated. Silica sands of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient and the fluctuation of frictional oscillation amplitude. Different sliding speeds were applied and external hard particle of different size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficients increase with hard particle due to the rapid changes of the effective contact area and the abrasion mode. Some embedded particles operating in two body abrasion mode help to increase the disc surface roughness and influence the stopping time of the disc. The standard deviation values of friction oscillation amplitude however were stable due to more wear debris produced and get compacted to form friction films assisting friction and they tend to reduce at medium speeds because many contact plateaus and effective contact area started to stabilize.

Enhancement of Wear Resistance of Copper With Tungsten Addition (≤20 wt %) by Powder Metallurgy Route

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Poulami Maji ◽  
R. K. Dube ◽  
Bikramjit Basu
Keyword(s):  
Wear Resistance ◽  
Wear Rate ◽  
Electrical Contacts ◽  
Operating Conditions ◽  
Fretting Wear ◽  
Wear Loss ◽  
Composite Surface ◽  
The Coefficient Of Friction ◽  
Improved Performance ◽  
Pure Cu

Copper–tungsten composite materials are developed for applications such as electrical contacts, resistance electrodes, and contact tips in welding guns as well as for components requiring higher wear resistance. In addition to the aspect of improved performance, it is scientifically interesting to assess the tribological properties, and therefore the objectives of the present work include, to determine the role of W additions in improving the fretting wear resistance of Cu for electrical applications, to determine the optimum concentration for W additions, and to identify the mechanisms responsible for fretting wear improvements. In addressing these issues, a planned set of fretting wear tests were conducted on powder metallurgically processed Cu–W composites (maximum W content of 20 wt %) against steel counterbody under varying load (up to 10 N) for 10,000 cycles. It has been observed that at lower loads of 2 N, the coefficient of friction (COF) recorded was ∼0.9 for the Cu–20 wt % W/steel, whereas it was ∼0.85 for a pure Cu/steel couple. Under similar operating conditions with the increase in load, the COF decreases to 0.5 at 10 N load, irrespective of the composition of the Cu–W composite. Furthermore, the incorporation of 5 wt % W has reduced the volumetric wear loss by 4–6 folds in comparison to unreinforced Cu. The addition of even higher percentage of W has led to increase its wear resistance by ∼10 folds. Under the investigated conditions, the wear rate systematically decreases with the increase in load for all the tested Cu–W composites. Based on the topographical observation of worn surfaces, it is observed that wear mechanisms for the Cu and Cu–W composites are tribochemical wear, adhesive wear, and abrasive wear. The incorporation of harder W particles (5 wt % or more) help in abrading the steel ball and in forming a dense tribolayer of FexOy, which effectively reduces wear rate and hence, increases wear resistance of the Cu–W composite surface in reference to unreinforced Cu.

Paper 5: Relaxation Oscillations on a Machine Tool Slideway

1969 ◽  
Vol 184 (12) ◽  
pp. 33-39
Author(s):  
D. G. Stewart ◽  
J. B. Hunt
Keyword(s):  
Machine Tool ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Empirical Relation ◽  
Oscillation Amplitude ◽  
Feed Speed ◽  
Relaxation Oscillations ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Machine Configuration

An investigation into the variation of the coefficient of friction during stick-slip sliding of a machine tool carriage is reported. The errors of position induced by the oscillation at feed speeds approaching zero, and at the critical speed when the oscillation amplitude is at a maximum, were measured and the results are given in a non-dimensional empirical relation which includes the effect of system natural frequency and feed speed. The amplitudes of the errors during sliding are shown to remain substantially constant at feed speeds below a critical value for any given machine configuration. At speeds above the critical the oscillations are rapidly damped out. The value of the critical velocity is shown to be a function of bearing pressure. The magnitude of the errors is seen to depend on the system natural frequency, there being a rapid rise in errors with system natural frequencies below about 60 rad/s.

scholarly journals Dynamics of a vibration system, taking into account the hereditary type friction and the mobility of a vibration limiter

2018 ◽  
Vol 226 ◽  
pp. 03022
Author(s):  
Vladimir S. Metrikin ◽  
Leonid A. Igumnov ◽  
Mikhail V. Zaitsev ◽  
Aleksandr V. Boev
Keyword(s):  
Classical Method ◽  
Functional Dependence ◽  
Variable Structure ◽  
Mapping Method ◽  
Research Approach ◽  
Vibration System ◽  
Friction Forces ◽  
Periodic Action ◽  
Point Mapping ◽  
The Coefficient Of Friction

The paper investigates the dynamics of some vibration systems taking into account the hereditary-type dry friction and mobility of a vibration limiter. The interaction of the vibration limiter and the vibration system occurs either according to Newton’s hypothesis (an absolutely rigid limiter) or softly (the limiter is mobile). A general mathematical model (MM) of systems has been developed, which is highly non-linear nonautonomous system with variable structure. A numerical-analytical approach using the mathematical apparatus of the point mapping method is implemented to study the dynamics of the MM. The peculiarity in the research approach is that the point mapping is not formed by the classical method (mappings of the Poincaré surface into itself), but by the duration of relative rest of the vibration system, which greatly facilitated the process of point mapping and its detailed study. The presence of floating boundaries of slip-motion plates required the creation of an original approach in constructing point mapping and interpreting the results obtained. The structure of the phase portrait of the MM as a function of the characteristics of the sliding and state friction forces, as well as on the type and position of the limiter was studied using the developed research methodology and the created software product. Based on the character of changes in bifurcation diagrams, it was possible to determine the main laws of changes in the motion regimes (occurrence of random complexity via the period possible transfer to chaos doubling process) when changing the parameters of the vibration system (amplitude and frequency of periodic action, the form of the functional dependence describing the change in the coefficient of friction of relative rest. Analytical results with and without a vibration limiter are compared.

scholarly journals A STUDY TO ASSESS THE EFFECTIVENESS OF SELECTED YOGA ON THE LEVEL OF ANXIETY, PREGNANCY DISCOMFORTS, CLINICAL PARAMETERS, MATERNAL AND NEONATAL OUTCOME AMONG PRIMIGRAVIDA WOMEN

2021 ◽  
Vol 9 (10) ◽  
pp. 1307-1310
Author(s):  
V. Vijayalakshmi ◽  
N. Jaya
Keyword(s):  
Pregnant Women ◽  
Neonatal Outcome ◽  
Human Life ◽  
Optimal Level ◽  
Research Approach ◽  
Study Group ◽  
Hormonal Changes ◽  
Post Test ◽  
Quasi Experimental ◽  
Relaxation Practice

Background: Pregnancy is a wonderful landmark in the life of a woman. It is the origin of human life. Pregnancy is a time of physical and hormonal changes and of emotional and psychological preparation for motherhood. Comforting techniques may enhance the women to settle and provide with an appreciation of personal capabilities. Therefore yoga can be an effective way to emancipate women during labour and to assist in attaining and maintaining their optimal level of functioning. Yoga is the great way to stay fit during pregnancy because yoga posture can easily meet the needs of pregnant women. It educates pregnant women to listen to their body and reduce stress and anxiety, and to calm the mind. Methodology: The research approach selected for this study was Quasi experimental -Pre and Post test design. The intervention for study group consisted of selected yoga which includes Asanas (tadasana, utkatasana, katichakrasana, konasana, ardhatitali, purnatitali), pranayama (nadishodhana, bhramari, sheetkari, sheetali, OM chanting), ashwini mudra, deep relaxation practice from 28th weeks of pregnancy till delivery. Result: There was a significant reduction in level of anxiety and pregnancy discomfort for primigravida women and improved maternal and neonatal outcome. The selected yoga was found to be effective in reduction of anxiety and pregnancy discomfort and improved the maternal and neonatal outcome for study group. Conclusion: Regular practices of selected yoga were effective in minimizing the level of anxiety during pregnancy, pregnancy discomfort and improving maternal and neonatal outcome.

Effects of External Hard Particles on Brake Friction Characteristics During Hard Braking

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
M. K. Abdul Hamid ◽  
G. W. Stachowiak
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Contact Area ◽  
Oscillation Amplitude ◽  
Stopping Time ◽  
Hard Particle ◽  
Friction Coefficients ◽  
Hard Particles ◽  
Effective Contact ◽  
Friction Oscillation

The effects of external hard particles on the friction coefficients and its oscillation amplitudes during hard braking were investigated. Silica sands of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient and the fluctuation of frictional oscillation amplitude. Different sliding speeds were applied and external hard particle of different size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficients increase with hard particle due to the rapid changes of the effective contact area and the abrasion mode. Some embedded particles operating in two body abrasion mode help to increase the disc surface roughness and influence the stopping time of the disc. The standard deviation values of friction oscillation amplitude however were stable due to more wear debris produced and get compacted to form friction films assisting friction and they tend to reduce at medium speeds because many contact plateaus and effective contact area started to stabilize.

Optimisasi Model Analisa Sensitivitas Primal–Dual dalam Management Produksi Dodol

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Iin Maulina ◽  
Siti Rusdiana ◽  
Rini Oktavia
Keyword(s):  
Sensitivity Analysis ◽  
Objective Function ◽  
Operation Research ◽  
Raw Materials ◽  
Applied Mathematics ◽  
Optimal Solution ◽  
Optimal Level ◽  
Research Problems ◽  
Dual Analysis ◽  
Primal Dual

Optimalisasi adalah cabang matematika terapan yang mempelajari masalah-masalah operasi riset dengan tujuan untuk memaksimalkan atau meminimalkan besaran tertentu. Dalam penelitian ini, kami akan menerapkan konsep optimasi pada mengoptimalkan kegiatan produksi di CV. Sentra Halia Sabang yang merupakan industri rumah tangga yang memproduksi dodol dalam kotak kemasan. Dengan melakukan penelitian tentang kegiatan produksi di CV. Sentra Halia Sabang, ditentukan bahwa fungsi tujuan adalah untuk memaksimalkan keuntungan perusahaan, yang dimodelkan sebagai Z=7537x1+5871x2+7887x3+6151x4+7987x5+6231x6+7909x7+6171x8+8037x9+6271x10+8629x11, di mana xi mewakili jumlah produksi untuk setiap jenis dodol. Selanjutnya, juga ditinjau sumber daya terbatas yang digunakan oleh perusahaan seperti jumlah bahan baku, waktu, maksimum dan batas minimum produksi. Pemrosesan data dilakukan dengan menggunakan perangkat lunak LINDO. Analisis yang digunakan adalah analisis dual primal yang dilanjutkan dengan analisis sensitivitas. Hasil penelitian ini menunjukkan bahwa produksi CV. Sentra Halia Sabang hampir mencapai level optimal. Jika perusahaan berproduksi dalam kondisi optimal, laba yang bisa diperoleh adalah Rp 195.330. Analisis dual primal menunjukkan bahwa ada sumber daya yang belum digunakan secara optimal, yang bisa dilihat dari nilai slack / surplus pada beberapa sumber daya. Dalam analisis sensitivitas, beberapa variasi penambahan pada masing-masing koefisien fungsi tujuan diterapkan. Hasil analisis sensitivitas menunjukkan bahwa penambahan koefisien fungsi tujuan sebesar Rp 150 tidak akan mempengaruhi solusi optimal awal.   Optimization is a part of applied mathematics that studies operation research problems with the aim to maximize or minimize a certain magnitude. In this research, we will apply the optimization concepts on optimizing production activities in CV. Sentra Halia Sabang which is a home industry producing dodol in a packing box. By doing research on production activities at CV. Sentra Halia Sabang, it was determined that the objective function is to maximize the profits of the company, which is modeled as Z=7537x1+5871x2+7887x3+6151x4+7987x5+6231x6+7909x7+6171x8+8037x9+6271x10+8629x11, where xi represents the amount of productions for each type of dodol. Next, it is also reviewed the limited resources used by the company such as the amount of raw materials, the time, the maximum and the minimum limit of production. Data processing is performed using software LINDO. The analyses applied were the primal dual analysis that was continued with the sensitivity analysis. The results of this study indicate that the production of CV. Sentra Halia Sabang almost reached the optimal level. If the company produces in optimal conditions, the profit that can be obtained is Rp 195 430. The primal dual analyses show that there are resources that have not been used optimally, that can be seen from the value of slack / surplus on some resources. In the sensitivity analysis, some various addition on each of the coefficients of the objective function were applied. The result of the sensitivity analysis show that the addition of the coefficients of the objective function as much as Rp 150 will not affect the initial optimal solution.

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