Simulation of the Friction Coefficient of Paper-Based Wet Clutch With Wavy Separators

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Fumitaka Yoshizumi ◽  
Hirofumi Tani ◽  
Shuzo Sanda
Keyword(s):  
Friction Coefficient ◽  
Wave Height ◽  
Fluid Pressure ◽  
Negative Slope ◽  
Large Wave ◽  
Detailed Model ◽  
Model Combining ◽  
Fiber Contact ◽  
Microscale Model ◽  
Simulation Results

To simulate the change rate of the friction coefficient μ with respect to the sliding speed V, that is, the μ-V slope, a model combining macroscale and microscale phenomena is proposed. The macroscale model obtains distributions of the fluid pressure and fiber contact pressure over the whole engagement face, and the microscale model obtains the friction coefficient of each fiber contact through a detailed model for single-protuberance fiber contact. An experiment was conducted to obtain the μ-V slope by changing the wave height of separator faces, and the simulation and experimental results were compared. The combined model is advantageous for representing experimental μ-V relationships at small and large wave heights in comparison with models using only the macroscale behavior. Both experimental and simulation results showed the μ-V slope becoming more negative with increasing wave height. The simulation results revealed possible causes for the negative slope. In the wavy separator, the fluid friction that contributes to the positive slope is difficult to achieve due to the large film thickness, and the load-sharing ratio of the fiber contact tends to decrease due to wedge action of the fluid film. These phenomena shift the μ-V slope to the negative.

Modeling and Simulation of Clamp Band Dynamic Envelope in a LV/SC Separation System

2011 ◽  
Vol 141 ◽  
pp. 359-363 ◽  
Author(s):  
Jun Lan Li ◽  
Shao Ze Yan ◽  
Xue Feng Tan
Keyword(s):  
Friction Coefficient ◽  
Modeling And Simulation ◽  
Band System ◽  
Separation Process ◽  
Impact Behavior ◽  
Separation System ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Simulation Results ◽  
Contact Impact

The clamp band system is a typical locked and separated device of the launch vehicle (LV) / the spacecraft (SC), and its release-separation process is one of the important factors that affect the LV/SC separation movement. A nonlinear spring-damper model was employed to describe the contact-impact behavior between the V-segment of the clamp band and the LV/SC interface, and lumped mass method was used to depict the clamp band. By using ADAMS, a dynamic model of the clamp band system was established. The simulation results show that the impulse of the explosive bolts and the stiffness of lateral-restraining springs have significant effects on the clamp band dynamic envelope. The shock of the satellite-vehicle separation is very vulnerable to the clamp band pretension and the friction coefficient between the V-segment and the LV/SC interface.

THE INFLUENCE OF CENTRE BOW LENGTH ON SLAMMING LOADS AND MOTIONS OF LARGE WAVE-PIERCING CATAMARANS

2021 ◽  
Vol 160 (A1) ◽  
Author(s):  
J R Shahraki ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Wave Height ◽  
Full Scale ◽  
Bending Moments ◽  
Regular Waves ◽  
Large Wave ◽  
Towing Tank ◽  
Segmented Model ◽  
Model Experiments ◽  
Slamming Load ◽  
Wave Induced

The effect of various centre bow lengths on the motions and wave-induced slamming loads on wave-piercing catamarans is investigated. A 2.5 m hydroelastic segmented model was tested with three different centre bow lengths and towed in regular waves in a towing tank. Measurements were made of the model motions, slam loads and vertical bending moments in the model demi-hulls. The model experiments were carried out for a test condition equivalent to a wave height of 2.68 m and a speed of 20 knots at full scale. Bow accelerations and vertical bending moments due to slamming showed significant changes with the change in centre bow, the longest centre bow having the highest wave-induced loads and accelerations. The increased volume of displaced water which is constrained beneath the bow archways is identified as the reason for this increase in the slamming load. In contrast it was found that the length of centre bow has a relatively small effect on the heave and pitch motions in slamming conditions.

scholarly journals REPRODUCTION ANALYSIS OF HUMAN DRIFTING BEHAVIOR DURING TSUNAMI USING NUMERICAL CALCULATION

2020 ◽  
pp. 34
Author(s):  
Riko Morita ◽  
Taro Arikawa
Keyword(s):  
Numerical Calculation ◽  
Wave Height ◽  
Prediction Method ◽  
Great East Japan Earthquake ◽  
Numerical Calculations ◽  
Water Tank ◽  
Maximum Wave Height ◽  
Hydraulic Experiment ◽  
Secondary Damage ◽  
Simulation Results

Along with the 2011 Great East Japan Earthquake (Mw 9.0), a huge tsunami exceeding a maximum wave height of 15 m occurred. Many people and objects were destroyed and drifted by the tsunami. In addition, these debris were transported to various places that could not be predicted, resulting in significant secondary damage and increase in the number of missing. Therefore, in order to reduce the amount of damage, it is important to predict the behavior and landing points of person after set adrift in a tsunami. The best way to increase the rescue rate is to predict in advance the area that people will be drifted, and prioritize searching operations at that area. Although there has been considerable number of studies which handle the drifting behavior of containers and ships (e.g., Kaida et al., 2016), the prediction of drifting areas focusing on people has not been conducted. Moreover, a drifting area prediction method has not yet been established. The purpose of this study is to conduct a hydraulic experiment using a flat water tank, and observe the drifting area of the drifting object. Then, we conducted numerical calculations and compared simulation results with the experimental ones.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/1yhKuodhCbg

scholarly journals Heterogeneous stresses and deformation mechanisms at shallow crustal conditions, Hungaroa Fault Zone, Hikurangi Subduction Margin, New Zealand

2020 ◽  
Author(s):  
Carolyn Boulton ◽  
Marcel Mizera ◽  
Maartje Hamers ◽  
Inigo Müller ◽  
Martin Ziegler ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Fault Zone ◽  
Mixed Mode ◽  
Fluid Pressure ◽  
Fault Zones ◽  
Deformation Mechanisms ◽  
Multiple Observations ◽  
Calcite Veins ◽  
Dynamic Recrystallisation ◽  
Clumped Isotope

<p>The Hungaroa Fault Zone (HFZ), an inactive thrust fault along the Hikurangi Subduction Margin, accommodated large displacements (~4–10 km) at the onset of subduction in the early Miocene. Within a 40 m-wide high-strain fault core, calcareous mudstones and marls display evidence for mixed-mode viscous flow and brittle fracture, including: discrete faults; extensional veins containing stretched calcite fibers; shear veins with calcite slickenfibers; calcite foliation-boudinage structures; calcite pressure fringes; dark dissolution seams; stylolites; embayed calcite grains; and an anastomosing phyllosilicate foliation.</p><p>Multiple observations indicate a heterogeneous stress state within the fault core. Detailed optical and electron backscatter diffraction-based texture analysis of syntectonic calcite veins and isoclinally folded limestone layers within the fault core reveal that calcite grains have experienced intracrystalline plasticity and interface mobility, and local subgrain development and dynamic recrystallisation. The recrystallized grain size in two calcite veins of 6.0±3.9 µm (n=1339; 1SD; HFZ-H4-5.2m_A;) and 7.2±4.2µm (n=406; 1SD; HFZ-H4-19.9m) indicate high differential stresses (~76–134 MPa). Hydrothermal friction experiments on a foliated, calcareous mudstone yield a friction coefficient of μ≈0.35. Using this friction coefficient in the Mohr-Coulomb failure criterion yields a maximum differential stress of 55 MPa at 4 km depth, assuming a minimum principal stress equal to the vertical stress, an average sediment density of 2350 kg/m<sup>3</sup>, and hydrostatic pore fluid pressure. Interestingly, calcareous microfossils within the foliated mudstone matrix are undeformed. Moreover, calcite veins are oriented both parallel to and highly oblique to the foliation, indicating spatial and/or temporal variations in the maximum principle stress azimuth.</p><p>To further constrain HFZ deformation conditions, clumped isotope geothermometry was performed on six syntectonic calcite veins, yielding formation temperatures of 79.3±19.9°C (95% confidence interval). These temperatures are well below those at which dynamic recrystallisation of calcite is anticipated and exclude shear heating and the migration of hotter fluids as an explanation for dynamic recrystallisation of calcite at shallow crustal levels (<5 km depth).</p><p>Our results indicate that: (1) stresses are spatiotemporally heterogeneous in crustal fault zones containing mixtures of competent and incompetent minerals; (2) heterogeneous deformation mechanisms, including frictional sliding, pressure solution, dynamic recrystallization, and mixed-mode fracturing accommodate slip in shallow crustal fault zones; and (3) brittle fractures play a pivotal role in fault zone deformation by providing fluid pathways that promote fluid-enhanced recovery and dynamic recrystallisation in the deforming calcite at remarkably low temperatures. Together, field geology, microscopy, and clumped isotope geothermometry provide a powerful method for constraining the multiscale slip behavior of large-displacement fault zones.</p>

scholarly journals Comparisons Between Braking Experiments and Longitudinal Train Dynamics Using Friction Coefficient and Braking Pressure Modeling in a Freight Train

2020 ◽  
Vol 14 (1) ◽  
pp. 154-163
Author(s):  
Don Bum Choi ◽  
Rag-Gyo Jeong ◽  
Yongkook Kim ◽  
Jangbom Chai
Keyword(s):  
Friction Coefficient ◽  
Time Integration ◽  
Expansion Method ◽  
Dynamics Simulation ◽  
Dynamic Simulations ◽  
Freight Train ◽  
Emergency Braking ◽  
Braking Distance ◽  
Train Dynamics ◽  
Simulation Results

Background: This paper describes the predictions and validation of the pneumatic emergency braking performance of a freight train consisting of a locomotive and 20 wagons, generally operated in Korea. It suggests the possibility of replacing the expensive and time-consuming train running tests with longitudinal train dynamic simulations. Methods: The simulation of longitudinal train dynamics of a freight train uses the time integration method of EN 14531. For reasonable simulation results, the characteristics of the train and brake equipment must be considered. For the train characteristics, specifications provided by the vehicle manufacturer are used. The braking characteristics are analyzed by friction coefficient tests and a braking pressure model. The friction coefficients of a locomotive and wagons are tested with a dynamo test bench and statistically expanded to account for variability. Freight trains should take into account the braking delay time. To reflect this in the simulation, the brake cylinder pressure pattern model uses pressures and exponential empirical equations measured at selective positions in a train of 50 vehicles. The simulation results are validated in comparison with those of the braking tests of a freight train consisting of 1 locomotive and 20 wagons. Results: The results of the longitudinal dynamics simulation show very similar results to the running test results based on the speed profile and braking distance. Conclusion: In particular, the statistical expansion method of the friction coefficient enables robust prediction of the distribution of the braking distance. The simulation can reduce or make up for costly and time-consuming repeated braking tests and reduce the risks that may arise during testing.

Effect of the Friction Coefficient on Large Strain Extrusion Machining

2013 ◽  
Vol 273 ◽  
pp. 138-142 ◽  
Author(s):  
Ping Lin ◽  
Zi Chun Xie ◽  
Qing Li
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Nanostructured Materials ◽  
Deformation Behavior ◽  
Large Strain ◽  
Effective Strain ◽  
Finite Element Simulations ◽  
Friction Coefficients ◽  
Simulation Results

The present study focused on the influence of the friction coefficient on the deformation behavior in large strain extrusion machining (LSEM). A series of simulation results of effective strain were obtained under different friction coefficients by conducting finite element simulations with a FEM code. The results show that LSEM can produce different effective strains by changing the friction coefficients, thus enabling the fabrication of bulk nanostructured materials. An analysis of the variation of effective strain through the chip demonstrated that the chip deformed much more inhomogeneously when the friction coefficient became larger. The obtained results can offer valuable guidelines for later LSEM studies.

Spectral Analysis of Irregular Wave Impact on the Structure in Splash Zone

2002 ◽  
Author(s):  
Bing Ren ◽  
Yongxue Wang
Keyword(s):  
Spectral Analysis ◽  
Wave Height ◽  
Incident Wave ◽  
Impact Pressure ◽  
Splash Zone ◽  
Spectral Moment ◽  
Wave Impact ◽  
Large Wave ◽  
Irregular Wave ◽  
The Impact

The spectral analysis from experimental data of irregular wave impact on the structures with large dimension in the splash zone is presented. The experiments were conducted in the large wave-current tank in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. In the experiment, the target spectrum is JONSWAP spectrum, the significant wave height H1/3 is in the range from 0.1m to 0.3m, and the peak period of spectrum Tp in the range from 1.0s to 2.0s. The ratio of s/H1/3, which refers to the clearance of the subface of the structure above still water level (s) to the incident wave height, is between −0.1 and 0.4. The spectral analysis results of the irregular wave impact pressure on the subface of the structure under various case studies are presented. The distribution of spectral moment of the impact pressure on the structure along the subface is given. And the influence of different incident wave parameters and relative clearance s/H1/3 on the average spectral moment of impact pressure are discussed.

Tribometer for Dry Friction Measurement

1999 ◽  
Author(s):  
Marc Brandl ◽  
Friedrich Pfeiffer
Keyword(s):  
Coefficient Of Friction ◽  
Dry Friction ◽  
Stribeck Curve ◽  
Body System ◽  
Friction Measurement ◽  
Detailed Model ◽  
The Coefficient Of Friction ◽  
Simulation Results ◽  
Multi Body

Abstract This paper deals with the measurement of dry friction. A tribometer was developed in order to identify both the sticking and the sliding coefficient of friction. The aim was to determine the so called Stribeck-curve of any material in contact. The design of the plant is presented. Avoiding errors in recalculating the coefficient of friction, a detailed model of the plant as a multi body system with motor feedback was generated. Advantages of the tribometer are shown in simulations. Some results of measurements in comparison with simulation results are presented.

scholarly journals Sensitivity Analysis of Johnson-Cook Material Constants and Friction Coefficient Influence on Finite Element Simulation of Turning Inconel 718

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3121 ◽  
Author(s):  
Xiaoli Qiu ◽  
Xianqiang Cheng ◽  
Penghao Dong ◽  
Huachen Peng ◽  
Yan Xing ◽  
...  
Keyword(s):  
Residual Stress ◽  
Sensitivity Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
Constitutive Model ◽  
Cutting Force ◽  
Inconel 718 ◽  
Coulomb Friction ◽  
Cutting Conditions ◽  
Simulation Results

The Johnson-Cook (J-C) constitutive model, including five material constants (A, B, n, C, m), and the Coulomb friction coefficient (μ) are critical preprocessed data in machining simulations. Before they become reliable preprocessed data, investigating these parameters’ effect on simulation results benefits parameter-selecting. This paper aims to investigate the different influence of five settings of the J-C constitutive equation and Coulomb friction coefficient on the turning simulation results of Inconel 718 under low-high cutting conditions, including residual stress, chip morphology, cutting force and temperature. A three-dimensional (3-D) finite element model was built, meanwhile, the reliability of the model was verified by comparing the experiment with the simulation. Sensitivity analysis of J-C parameters and friction coefficient on simulation results at low-high cutting conditions was carried out by the hybrid orthogonal test. The results demonstrate that the simulation accuracy of Inconel 718 is more susceptible to strain hardening and thermal softening in the J-C constitutive model. The friction coefficient only has significant effects on axial and radial forces in the high cutting condition. The influences of the coefficient A, n, and m on the residual stress, chip thickness, cutting force and temperature are especially significant. As the cutting parameters increase, the effect of the three coefficients will change visibly. This paper provides direction for controlling simulation results through the adjustment of the J-C constitutive model of Inconel 718 and the friction coefficient.

Investigating the Effects of the Friction Coefficient and Tool Geometry on the Cup Thickness in the Deep Drawing Process of SPXI250 Alloy

2013 ◽  
Author(s):  
Iman Rostamsowlat ◽  
Ahmad Afsari ◽  
Maziar Janghorban
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Deep Drawing ◽  
The Other ◽  
Tool Geometry ◽  
Drawing Process ◽  
Nose Radius ◽  
Deep Drawing Process ◽  
Simulation Results ◽  
Thickness Variations

In this paper, effects of friction coefficient and tool geometry on the thickness variations of a cylindrical cup were studied. Blank is made of SPXI250 alloy sheet which was analyzed by Finite Element Method (FEM). This not been studied yet. Finite Element modeling of the deep drawing process was conducted using ABAQUS/EXPLICIT software. A set of appropriate die and punch were designed for experimental tests. The results of the simulation showed that a change in the friction coefficient of the die-blank interface leads to a significant changes in the cup thickness. Moreover, the results revealed that the influence of die nose radius on the final cup thickness variations is greater than that of the punch nose radius. The simulation results of this study were compared with the experimental results and those of the other investigators’. The comparisons of the experimental and simulation results with those of the other researchers were so satisfactory.

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