Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Rate Dependent Material Model for Helmet Pads

2020 ◽  
Author(s):  
Timothy G. Zhang ◽  
A. H. Fulton ◽  
K. Ravi-Chandar ◽  
Sikhanda S. Satapathy
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
High Speed ◽  
Material Model ◽  
High Speed Camera ◽  
Low Velocity ◽  
Rate Dependent ◽  
Military Helmet ◽  
The Impact ◽  
Impact Experiments

Abstract Foam pads are commonly used in sports and military helmet for energy absorption, form-fitting and comfort. Both for low velocity and high velocity applications, their rate-dependent mechanical properties need to be characterized to understand their ability to effectively modulate the transmitted stress pulse. Impact experiments were conducted on bilayer helmet pads at a range of velocities covering low to medium rates up to ∼7000/s. Images from high-speed camera were used to construct x-T diagrams to measure the shock speeds from the impact experiments. Numerical simulations were carried out to validate a foam pad model and to understand experimental uncertainties. The scatter in the measured shock speeds was found to be related to the scatter in the material properties.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

Simulation of High-Speed Cutting Process Based on ABAQUS

2011 ◽  
Vol 230-232 ◽  
pp. 1221-1225 ◽  
Author(s):  
Xia Yu ◽  
Xu Yao Sun ◽  
Dan Ke Wei
Keyword(s):  
High Speed ◽  
Chip Morphology ◽  
Material Model ◽  
Rake Angle ◽  
Cutting Process ◽  
Fe Model ◽  
High Speed Cutting ◽  
Line Technology ◽  
Chip Separation ◽  
The Impact

Using the separation line technology, established a FE model of two-dimensional cutting process for AISI4340 steel and discussed some basic theory and pivotal questions associated with the simulation of cutting process including the Johnson-Cook material model, the contact model between tool and chip, criteria of chip separation and so on. In order to study the impact of tool rake angle on the chip morphology and the cutting forces, the high-speed cutting process for AISI 4340 steel was simulated based on ABAQUS software. Also, analyzed the influence of mesh azimuth on the chip morphology and its temperature distribution.

scholarly journals The impact on global magnetohydrodynamic simulations from varying initialisation methods: results from GUMICS-4

2017 ◽  
Vol 35 (4) ◽  
pp. 907-922 ◽  
Author(s):  
Antti Lakka ◽  
Tuija I. Pulkkinen ◽  
Andrew P. Dimmock ◽  
Adnane Osmane ◽  
Ilja Honkonen ◽  
...  
Keyword(s):  
High Speed ◽  
Synthetic Data ◽  
Constant Density ◽  
Satellite Measurements ◽  
Wind Measurements ◽  
Sinusoidal Functions ◽  
Magnetohydrodynamic Simulations ◽  
The Impact ◽  
Different Parts ◽  
Good Agreement

Abstract. We investigate the effects of different initialisation methods of the GUMICS-4 global magnetohydrodynamic (MHD) simulation to the dynamics in different parts of the Earth's magnetosphere and hence compare five 12 h simulation runs that were initiated by 3 h of synthetic data and followed by 9 h of solar wind measurements using the OMNI data as input. As a reference, we use a simulation run that includes nearly 60 h of OMNI data as input prior to the 9 h interval examined with different initialisations. The selected interval is a high-speed stream event during a 10-day interval (12–22 June 2007). The synthetic initialisations include stepwise, linear and sinusoidal functions of the interplanetary magnetic field with constant density and velocity values. The results show that the solutions converge within 1 h to give a good agreement in both the bow shock and the magnetopause position. However, the different initialisation methods lead to local differences which should be taken into consideration when comparing model results to satellite measurements.

Dynamics of High Speed Roller Chain Drives

1995 ◽  
Author(s):  
Peter Fritz ◽  
Friedrich Pfeiffer
Keyword(s):  
High Speed ◽  
Contact Forces ◽  
System Structure ◽  
Unilateral Constraints ◽  
Roller Chain ◽  
Contact Configuration ◽  
Nonlinear Force ◽  
A Chain ◽  
The Impact ◽  
Chain Drives

Abstract This paper deals with roller chain drives applied in combustion engines. In order to find characteristics for an optimal design, all components of a chain drive are taken into account. For a detailed analysis of the chain strand vibrations and the contact configurations each chain link, sprocket and guide is treated as a separate body. A nonlinear force element describes the joint forces, including elasticity, damping, backlash and oil-displacement. To determine real contact forces between a link and a sprocket or a guide, the exact contour and the mutual dependence of the contacts are considered. The impact of one link may influence the other links in such a manner that their contact configuration may change. In the mechanical model these contacts are represented by unilateral constraints. Applying the formulation of the linear complementarities including additional inequality conditions, the determination of a valid contact configuration after a change in the system structure is simplified.

scholarly journals Growth and instability of the liquid rim in the crown splash regime

2014 ◽  
Vol 752 ◽  
pp. 485-496 ◽  
Author(s):  
G. Agbaglah ◽  
R. D. Deegan
Keyword(s):  
Thin Film ◽  
High Speed ◽  
Unstable Mode ◽  
Linear Stability Theory ◽  
Scaling Relations ◽  
X Ray ◽  
X Ray Imaging ◽  
Secondary Droplets ◽  
The Impact ◽  
Good Agreement

AbstractWe study the formation, growth and disintegration of jets following the impact of a drop on a thin film of the same liquid for $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\mathit{We}<1000$ and $\mathit{Re}<2000$ using a combination of numerical simulations and linear stability theory (Agbaglah, Josserand & Zaleski, Phys. Fluids, vol. 25, 2013, 022103). Our simulations faithfully capture this phenomena and are in good agreement with experimental profiles obtained from high-speed X-ray imaging. We obtain scaling relations from our simulations and use these as inputs to our stability analysis. The resulting predictions for the most unstable wavelength are in excellent agreement with experimental data. Our calculations show that the dominant destabilizing mechanism is a competition between capillarity and inertia but that deceleration of the rim provides an additional boost to growth. We also predict over the entire parameter range of our study the number and timescale for formation of secondary droplets formed during a splash, based on the assumption that the most unstable mode sets the droplet number.

Air entrapment by a falling water mass

1995 ◽  
Vol 294 ◽  
pp. 181-207 ◽  
Author(s):  
Hasan N. Oguz ◽  
Andrea Prosperetti ◽  
Ali R. Kolaini
Keyword(s):  
High Speed ◽  
Water Mass ◽  
Boundary Integral ◽  
Surface Shape ◽  
Water Tank ◽  
Air Entrapment ◽  
Free Surface Shape ◽  
Large Water ◽  
The Impact ◽  
Good Agreement

The impact of a nearly cylindrical water mass on a water surface is studied both experimentally and theoretically. The experiments consist of the rapid release of water from the bottom of a cylindrical container suspended above a large water tank and of the recording of the free-surface shape of the resulting crater with a high-speed camera. A bubble with a diameter of about twice that of the initial cylinder remains entrapped at the bottom of the crater when the aspect ratio and the energy of the falling water mass are sufficiently large. Many of the salient features of the phenomenon are explained on the basis of simple physical arguments. Boundary-integral potential-flow simulations of the process are also described. These numerical results are in fair to good agreement with the observations.

Effects of Grain Size on Ballistic Response of Copper Materials

2017 ◽  
Author(s):  
Ge He ◽  
Yangqing Dou ◽  
Xiang Guo ◽  
Yucheng Liu
Keyword(s):  
Grain Size ◽  
High Speed ◽  
Damage Model ◽  
Material Model ◽  
Coarse Grained ◽  
Ballistic Performance ◽  
Fragmentation Behavior ◽  
Constitutive Material Model ◽  
Comparison Results ◽  
The Impact

Numerical simulations were conducted to compare ballistic performance and penetration mechanism of copper (Cu) with four representative grain sizes. Ballistic limit velocities for coarse-grained (CG) copper (grain size ≈ 90 μm), regular copper (grain size ≈ 30 μm), fine-grained (FG) copper (grain size ≈ 890 nm), and ultrafine-grained (UG) copper (grain size ≈ 200 nm) were determined for the first time through the simulations. It was found that the copper with reduced grain size would offer higher strength and better ductility, and therefore renders improved ballistic performance then the CG and regular copper. High speed impact and penetration behavior of the FG and UG copper was also compared with the CG coppers strengthened by nanotwinned (NT) regions. The comparison results showed the impact and penetration resistance of UG copper is comparable to the CG copper strengthened by NT regions with the minimum twin spacing. Therefore, besides the NT regions-strengthened copper, the single phase copper with nanoscale grain size could also be a strong candidate material for better ballistic protection. A computational modeling and simulation framework was proposed for this study, in which Johnson-Cook (JC) constitutive material model is used to predict the plastic deformation of Cu and Ni; JC damage model is to capture the penetration and fragmentation behavior of Cu; Bao-Wierzbicki (B-W) failure criterion defines the material’s failure mechanisms; and temperature increase during this adiabatic penetration process is given by the Taylor-Quinney method.

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