Figure 19.4 Frictional (F) and normal force (F) vectors versus

1999 ◽  
pp. 408-409
Keyword(s):  
Normal Force

Rheological characterization of tack and viscoelasticity of compositions of crepe coating used in the Yankee dryer

TAPPI Journal ◽  
2019 ◽  
Vol 18 (11) ◽  
pp. 641-649
Author(s):  
JOSHUA OMAMBALA ◽  
CARL MCINTYRE
Keyword(s):  
Normal Force ◽  
Weight Ratio ◽  
Good Combination ◽  
Rheological Characterization ◽  
Nonlinear Viscoelastic ◽  
Coating Composition ◽  
Linear And Nonlinear ◽  
Work Done ◽  
Tissue Production

The vast majority of tissue production uses creping to achieve the required set of properties on the base sheet. The Yankee coating helps to develop the desired crepe that in turn determines properties such as bulk and softness. The adhesion of the sheet to the Yankee surface is a very important characteristic to consider in achieving the desired crepe. The coating mix usually consists of the adhesive, modifier, and release. A good combination of these components is essential to achieving the desired properties of the tissue or towel, which often are determined by trials on the machine that can be time consuming and lead to costly rejects. In this paper, five compositions of an industrial Yankee coating adhesive, modifier, and release were examined rheologically. The weight ratio of the adhesive was kept constant at 30% in all five compositions and the modifier and release ratios were varied. The normal force and work done by the different compositions have been shown at various temperatures simulating that of the Yankee surface, and the oscillatory test was carried out to explain the linear and nonlinear viscoelastic characteristic of the optimal coating composition.

scholarly journals Effect of Water-Based Nanolubricants in Ultrasonic Vibration Assisted Grinding

2018 ◽  
Vol 2 (4) ◽  
pp. 80 ◽  
Author(s):  
Mir Molaie ◽  
Ali Zahedi ◽  
Javad Akbari
Keyword(s):  
Surface Roughness ◽  
Specific Energy ◽  
Material Removal ◽  
Normal Force ◽  
Tangential Force ◽  
Process Efficiency ◽  
Multiwall Carbon Nanotube ◽  
Ultrasonic Vibrations ◽  
Mql Grinding ◽  
Water Based

Currently, because of stricter environmental standards and highly competitive markets, machining operations, as the main part of the manufacturing cycle, need to be rigorously optimized. In order to simultaneously maximize the production quality and minimize the environmental issues related to the grinding process, this research study evaluates the performance of minimum quantity lubrication (MQL) grinding using water-based nanofluids in the presence of horizontal ultrasonic vibrations (UV). In spite of the positive impacts of MQL using nanofluids and UV which are extensively reported in the literature, there is only a handful of studies on concurrent utilization of these two techniques. To this end, for this paper, five kinds of water-based nanofluids including multiwall carbon nanotube (MWCNT), graphite, Al2O3, graphene oxide (GO) nanoparticles, and hybrid Al2O3/graphite were employed as MQL coolants, and the workpiece was oscillated along the feed direction with 21.9 kHz frequency and 10 µm amplitude. Machining forces, specific energy, and surface quality were measured for determining the process efficiency. As specified by experimental results, the variation in the material removal nature made by ultrasonic vibrations resulted in a drastic reduction of the grinding normal force and surface roughness. In addition, the type of nanoparticles dispersed in water had a strong effect on the grinding tangential force. Hybrid Al2O3/graphite nanofluid through two different kinds of lubrication mechanisms—third body and slider layers—generated better lubrication than the other coolants, thereby having the lowest grinding forces and specific energy (40.13 J/mm3). It was also found that chemically exfoliating the graphene layers via oxidation and then purification prior to dispersion in water promoted their effectiveness. In conclusion, UV assisted MQL grinding increases operation efficiency by facilitating the material removal and reducing the use of coolants, frictional losses, and energy consumption in the grinding zone. Improvements up to 52%, 47%, and 61%, respectively, can be achieved in grinding normal force, specific energy, and surface roughness compared with conventional dry grinding.

scholarly journals Fretting Wear Behavior of Three Kinds of Rubbers under Sphere-On-Flat Contact

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2153
Author(s):  
Tengfei Zhang ◽  
Jie Su ◽  
Yuanjie Shu ◽  
Fei Shen ◽  
Liaoliang Ke
Keyword(s):  
Normal Force ◽  
Wear Behavior ◽  
Displacement Amplitude ◽  
Fretting Wear ◽  
Butadiene Rubber ◽  
Force Frequency ◽  
Sealing Performance ◽  
Rubber Surface ◽  
Sealing Materials ◽  
Flat Contact

Rubbers are widely used in various fields as the important sealing materials, such as window seal, door seal, valve, pump seal, etc. The fretting wear behavior of rubbers has an important effect on their sealing performance. This paper presents an experimental study on the fretting wear behavior of rubbers against the steel ball under air conditions (room temperature at 20 ± 2 °C and humidity at 40%). Three kinds of rubbers, including EPDM (ethylene propylene diene monomer), FPM (fluororubber), and NBR (nitrile–butadiene rubber), are considered in experiments. The sphere-on-flat contact pattern is used as the contact model. The influences of the displacement amplitude, normal force, frequency, and rubber hardness on the fretting wear behavior are discussed in detail. White light profiler and scanning electron microscope (SEM) are used to analyze the wear mechanism of the rubber surface. The fretting wear performances of three rubbers are compared by considering the effect of the displacement amplitude, normal force, frequency, and rubber hardness. The results show that NBR has the most stable friction coefficient and the best wear resistance among the three rubbers.

Effect of Variations in Weight or Normal Acceleration on the Ceiling of Jet-Propelled Aircraft

1955 ◽  
Vol 59 (534) ◽  
pp. 435-437
Author(s):  
P. L. Sutcliffe
Keyword(s):  
High Altitude ◽  
Normal Force ◽  
Control Surface ◽  
Military Aircraft ◽  
Longitudinal Control ◽  
The Past ◽  
Normal Acceleration

The ability to manoeuvre at high altitude has become one of the main requirements in the design of modern military aircraft. Ability to manoeuvre enables the fighter pilot to execute tight turns during the attack on a bomber and the bomber pilot to perform evasive manoeuvres and so make the task of the fighter more difficult.Normally the main manoeuvre considered is the application of increased normal acceleration, or g, and if we assume that (a) there is sufficient pitching power available from the longitudinal control surface to increase the wing incidence to give the necessary increase in normal force, and (b) that the new wing incidence is below the stalling incidence of the wing, then the degree of manoeuvrability available is a function of thrust and drag alone. In the past the manoeuvrability required at a given altitude has been expressed in terms of the rate of climb available at that altitude and thus we have such definitions as “ the 1,000 ft./min. ceiling ” and so on.

Roller Cutter Forces

1970 ◽  
Vol 10 (01) ◽  
pp. 57-65 ◽  
Author(s):  
C.R. Peterson
Keyword(s):  
Normal Force ◽  
Penetration Rate ◽  
Rolling Force ◽  
Skew Angle ◽  
Average Force ◽  
Straight Line ◽  
Bearing Load ◽  
Boring Machines ◽  
Force Reduction ◽  
Cutter Head

Abstract An experimental technique is described in which three component forces are measured while a typical toothed cutter is rolled in a straight line over a rock sample. The technique includes the attainment of a steady state in which volume-averaged penetration is correlated with average force during penetration is correlated with average force during the removal of several layers from the rock surface. Simple rolling and skewed rolling forces are measured. The cutter was artificially dulled for some of the measurements. Surprisingly little variation in force requirement is noted. A qualitative explanation is suggestedThe normal force requirement is substantially reduced when the cutter is skewed. A theoretical description of the force reduction is presented, showing reasonable agreement with the observed behavior in terms of cutter radius, tooth width, penetration and skew angle. penetration and skew angle Introduction Toothed roller cutters have long been in use on tricone bits, and they are in common use on boring machines. Yet the designer of boring machines is still faced with a dearth of good design information on the performance of such cutters. For example, what are the relationships between thrust, power, and penetration rate? How are these relationships influenced by rock properties and cutter configuration?While the data presented here provide answers to more specific questions than those mentioned above, these data are necessary for arriving at solutions to the broader questions. This work is restricted to one tooth type, typical of the wedge-shaped steel teeth used on medium rock. A limited range of rock types was tested; this coupled with the extreme variation of rock drillability, renders the data of limited value in predicting penetration rate. But the designer must predicting penetration rate. But the designer must answer questions even more important than the prediction of absolute penetration rate. For example, prediction of absolute penetration rate. For example, the cutter normal force is usually known in terms of the thrust to be applied to the cutter head. What is the torque or power required to rotate the cutter head? For an answer, one need know only the ratio of normal force to the tangential or rolling force. This ratio may be estimated from the present data. Variation of this ratio is reasonably small from one rock to another so that, lacking more specific information, these data can provide at least rough design estimates for other rocks. Tricone bits for soft to medium rock usually are constructed with skewed cutter elements that provide a "gouging and scraping action". Whatever the explanation, skewed cutters do provide increased drilling rate or, for a given drilling rate, a decreased thrust requirement. To my knowledge, skewed cutter elements have not been used on boring machines. If they were, bearing load could be reduced at a given penetration rate, or, conversely, an increased penetration rate could be obtained at the same penetration rate could be obtained at the same bearing load. Of course, a side load is introduced to the cutter bearing and this must be provided for. As for the rolling force, the designer really needs only the ratio of side-to-normal load. The present data indicate that this ratio is quite independent of rock type. The magnitude of the force reduction to be expected with skewed cutters is also of interest. The present data indicate that substantial reductions might be expected. A simple analytical model predicts the observed reduction reasonably well on the basis of the limited data available. EXPERIMENTAL APPARATUS AND TECHNIQUES Forces produced by a single cutter wheel rolling in a straight line over the rock specimen were measured. This simple geometry is experimentally convenient and is thought to be reasonably representative of cutter conditions on a large boring machine. Fig 1 illustrates the "linear apparatus" on which the measurements were made. The cutter wheel was rotatably mounted in a heavy yoke. SPEJ P. 57

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