Predicting Multi-Scale Dimensional Accuracy of Engine Cylinder by Honing

2017 ◽  
Author(s):  
Zaoyang Zhou ◽  
Xueping Zhang ◽  
Zhenqiang Yao ◽  
Lifeng Xi
Keyword(s):  
Surface Texture ◽  
Dimensional Accuracy ◽  
Scale Model ◽  
Cylinder Wall ◽  
Initial Shape ◽  
Abrasive Resistance ◽  
Micro Scale ◽  
Multi Scale ◽  
Macro Scale ◽  
Cylinder Bore

The deviations of cylinder bore dimensional accuracy have tremendous influence on engine performances including friction power loss, vibration, leak tightness between piston ring and cylinder wall, and abrasive resistance. Many researches were devoted to capturing cylinder dimensional accuracies by honing using analytical, experimental and simulation methods. These researches investigated the topography and roughness of the honed surface, the relationship between the process parameters and the dimensional accuracies. However, most researches focused on macro-scale dimensional accuracy and micro-scale surface texture respectively. To overcome the limitation, a multi-scale model for cylinder bore honing is proposed to predict the dimensional accuracy and surface texture of cylinder bore at macro-scale and micro-scale simultaneously. The model integrates the microscale factors of the honing stone abrasives distribution characteristics, abrasive wear process, previous cylinder surface topography, and macro-scale factors of cylinder geometry and honing head motion trajectory. A Force matching method is adopted to determine the feed depth of cylinder honing process. Thus the model can predict the roundness, cylindricity, roughness and Abbott-Firestone curve of the honed cylinder bore at multi-scale levels. Simulation results show that material removal distribution is closely related to cylinder bore initial shape deviations. The deviations with long wavelengths cannot be eliminated by the sequential honing.

Analytically Predicating the Multi-Dimensional Accuracy of the Honed Engine Cylinder Bore

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Xueping Zhang ◽  
Zaoyang Zhou ◽  
Zhenqiang Yao ◽  
Lifeng Xi
Keyword(s):  
Surface Texture ◽  
Dimensional Accuracy ◽  
Multiscale Model ◽  
Cylinder Surface ◽  
Initial Shape ◽  
Wear Process ◽  
Force Matching ◽  
Engine Cylinder ◽  
Cylinder Bore

Abstract The dimensional accuracy of engine cylinder bore at multiscale has a tremendous influence on engine performances including friction power loss, vibration, leak tightness between piston and cylinder, and wear resistance. Tremendous researches were devoted to predict the dimensional accuracies of the honed cylinder by means of analytical, experimental, and numerical simulation methods. The dimensional quality of the honed cylinder bore was usually determined by establishing the relationship between honing parameters and dimensional accuracies of the honed cylinder bore. However, most researches predicted dimensional accuracy at macroscale or surface texture at microscale, respectively. Few efforts were devoted to predict the dimensional quality of honed cylinder bore at both macroscale and microscale levels simultaneously. To explore a new understanding of the honing mechanism of the cylinder bore, a multiscale model is proposed to predict the dimensional accuracy and surface texture of cylinder bore generated from the honing process at the macroscale and microscale simultaneously. The model aims to integrate both microscale factors including honing stone abrasives distribution, abrasive wear process, previous cylinder surface topography, and macroscale factors including cylinder geometric features and honing head motion trajectory into a multiscale analytical analysis. A force matching method is adopted in the multiscale predictive model to determine the feed depth in the honing of the cylinder bore. Thus, the proposed multiscale analytical model possesses an excellent capacity to simultaneously predict the roundness and cylindricity of the honed cylinder bore, as well as the surface texture/roughness of the honed cylinder bore in terms of Abbott-Firestone curve. The simulated results also revealed that the material removal process is closely related to the initial shape deviations of the cylinder bore, which cannot be corrected, compensated, or eliminated by the subsequent honing process given the deviations are associated with wavelengths higher than 27 mm under the given honing condition.

Multi-scale density detection for yarn-dyed fabrics with deformed repeat patterns

2016 ◽  
Vol 87 (20) ◽  
pp. 2524-2540 ◽  
Author(s):  
Dejun Zheng ◽  
Lingheng Wang
Keyword(s):  
Computation Time ◽  
Registration Method ◽  
Decomposition Approach ◽  
Micro Scale ◽  
Detection Model ◽  
Multi Scale ◽  
Fabric Density ◽  
Macro Scale ◽  
Dyed Fabrics ◽  
Dyed Fabric

A new method combining the characteristics of macro-scale texture repeat patterns and micro-scale interwoven yarns of fabric images was proposed for yarn-dyed fabric density detection. The method was formulated in a research framework of multi-scale image processing and analysis. Firstly, a structure–texture decomposition approach was used to extract texture information and woven pattern details from the macro-scale fabric image. Secondly, a texture unit detection model was proposed to extract the texture units and to detect the yarn skewness in these texture units. Thirdly, a simple yet effective image registration method and a lightness gradient projection method were adopted to analyze the micro-scale fabric image and obtain the yarn locations in a texture unit. Finally, the average fabric density was calculated by coupling the near-regular features of texture units and yarn locations. The experiments showed that the proposed method was effective in detecting hundreds of yarns in the fabric samples and the computation time was very reasonable.

A Micro-Scale Model for Fiber Tow Characterization under Nondeterministic Assumption: Longitudinal and Transverse Permeability

2013 ◽  
Vol 554-557 ◽  
pp. 2348-2354 ◽  
Author(s):  
Pierpaolo Carlone ◽  
Gaetano S. Palazzo
Keyword(s):  
Scale Model ◽  
Liquid Composite Molding ◽  
Trial And Error ◽  
Flow Simulations ◽  
Micro Scale ◽  
Multi Scale ◽  
Representative Cell ◽  
Transverse Permeability ◽  
Composite Molding ◽  
Cure Models

Liquid Composite Molding processes are characterized by the impregnation of a dry fibrous perform by means of injection or infusion of a catalyzed resin. In recent years computational flow and cure models allowed for a remarkable time and cost compression in process planning with respect to trial and error procedures. In this contest multi-scale simulative approaches are gaining considerable attention and intriguing results have been recently presented. Most of the proposed models, however, rely on deterministic hypothesis, assuming perfect fiber packing and neglecting dimensional variations between fibers, in strong contrast with experimental observations. In this paper the influence of the stochastic variability of the fiber packing on tow permeability has been investigated by means of a CFD micro scale model. The variability of the microstructure defining the Representative Volume Element has been considered introducing random perturbations of the fiber packing. The components of the permeability tensor, in each case, have then been derived applying the Darcy model to flow simulations through the representative cell.

Prediction of Contact Area and Frictional Behaviour of Rubber on Rigid Rough Surfaces

2014 ◽  
Author(s):  
Hagen Lind ◽  
Matthias Wangenheim
Keyword(s):  
Contact Area ◽  
Surface Texture ◽  
Rough Surfaces ◽  
Scale Model ◽  
Real Contact Area ◽  
Contact Friction ◽  
Sliding Velocity ◽  
Normal Contact ◽  
Multi Scale ◽  
Frictional Behaviour

In the tire-road contact friction depends on several influencing variables (e.g. surface texture, real contact area, sliding velocity, normal contact pressure, temperature, tread block geometry, compound and on the existence of a lubrication film). A multi-scale model for prediction of contact area and frictional behaviour of rubber on rigid rough surfaces at different length scales is presented. Within this publication the multi-scale approach is checked regarding convergence. By means of the model influencing parameters like sliding velocity, compound and surface texture on friction and contact area will be investigated.

Multi-Scale Stereolithography Using Shaped Beams

2017 ◽  
Author(s):  
Huachao Mao ◽  
Yuen-Shan Leung ◽  
Yuanrui Li ◽  
Pan Hu ◽  
Wei Wu ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Path ◽  
Three Dimensional ◽  
Laser Exposure ◽  
Micro Scale ◽  
Multi Scale ◽  
Good Surface ◽  
Single Scale ◽  
Macro Scale ◽  
Micro Patterns

Current Stereolithography (SL) can fabricate three-dimensional (3D) objects in a single scale level, e.g. printing macro-scale or micro-scale objects. However, it is difficult for the SL printers to fabricate a 3D macro-scale object with micro-scale features. In the paper a novel SL-based multi-scale fabrication method is presented to address such a problem. The developed SL process can fabricate multi-scale features by dynamically changing the shape and size of a laser beam. Different shaped beams are realized by switching apertures with different micro-patterns. The laser beam without using any micro-patterns is used to fabricate the macro-scale features, while the shaped laser beams with smaller sizes are used to fabricate micro-patterned features. Accordingly, the tool path planning method for the multi-scale fabrication process are developed so that macro-scale and micro-scale features can be built by using different layer thicknesses, laser exposure time, and scanning paths. Compared with the conventional SL process based on a fixed laser beam size, our process can fabricate multi-scale features in a 3D object. It also has fast fabrication speed and good surface quality.

Finite Element Modeling of Multi-Scale Thermal Contact Resistance

2008 ◽  
Author(s):  
M. K. Thompson
Keyword(s):  
Finite Element ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Unit Area ◽  
Thermal Contact ◽  
Contact Model ◽  
Micro Scale ◽  
Multi Scale ◽  
Macro Scale ◽  
Scale Surface

Many traditional macro scale finite element models of thermal contact systems have incorporated the effect of micro scale surface topography by applying a constant value of thermal contact conductance (TCC) per unit area to the regions in contact. However, it has been very difficult to determine an appropriate TCC value for a given system and analysts typically had to rely on experimental data or values from the literature. This work presents a method for predicting micro scale TCC per unit area by incorporating micro scale surface roughness in a multi-scale iterative thermal/structural finite element contact model. The resulting TCC value is then used in a macro scale thermal/structural contact model with apparent surface form to predict the thermal contact resistance and overall thermal resistance for a commercial power electronics module.

scholarly journals Multi-scale atmospheric environment modelling for urban areas

2009 ◽  
Vol 3 (1) ◽  
pp. 53-57 ◽  
Author(s):  
A. A. Baklanov ◽  
R. B. Nuterman
Keyword(s):  
Urban Areas ◽  
Scale Effects ◽  
Urban Setting ◽  
Atmospheric Environment ◽  
Scale Model ◽  
Limited Area ◽  
Nested Models ◽  
Micro Scale ◽  
Multi Scale ◽  
Meso Scale

Abstract. Modern supercomputers allow realising multi-scale systems for assessment and forecasting of urban meteorology, air pollution and emergency preparedness and considering nesting with obstacle-resolved models. A multi-scale modelling system with downscaling from regional to city-scale with the Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM) and to micro-scale with the obstacle-resolved Micro-scale Model for Urban Environment (M2UE) is suggested and demonstrated. The M2UE validation results versus the Mock Urban Setting Trial (MUST) experiment indicate satisfactory quality of the model. Necessary conditions for the choice of nested models, building descriptions, areas and resolutions of nested models are analysed. Two-way nesting (up- and down-scaling), when scale effects both directions (from the meso-scale on the micro-scale and from the micro-scale on the meso-scale), is also discussed.

A Multi-Scale Finite Element Model for Shock Wave-Induced Axonal Brain Injury

2008 ◽  
Author(s):  
M. Sotudeh-Chafi ◽  
N. Abolfathi ◽  
A. Nick ◽  
V. Dirisala ◽  
G. Karami ◽  
...  
Keyword(s):  
Shock Wave ◽  
Brain Injury ◽  
Shock Waves ◽  
Brain Tissue ◽  
Scale Model ◽  
Micro Scale ◽  
Multi Scale ◽  
Injury Criteria ◽  
Wave Induced ◽  
The Brain

Traumatic brain injuries (TBIs) involve a significant portion of human injuries resulting from a wide range of civilian accidents as well as many military scenarios. Axonal damage is one of the most common and important pathologic features of traumatic brain injury. Axons become brittle when exposed to rapid deformations associated with brain trauma. Accordingly, rapid stretch of axons can damage the axonal cytoskeleton, resulting in a loss of elasticity and impairment of axoplasmic transport. Subsequent swelling of the axon occurs in discrete bulb formations or in elongated varicosities that accumulate organelles. Ultimately, swollen axons may become disconnected [1]. The shock waves generated by a blast, subject all the organs in the head to displacement, shearing and tearing forces. The brain is especially vulnerable to these forces — the fronts of compressed air waves cause rapid forward or backward movements of the head, so that the brain rattles against the inside of the skull. This can cause subdural hemorrhage and contusions. The forces exerted on the brain by shock waves are known to damage axons in the affected areas. This axonal damage begins within minutes of injury, and can continue for hours or days following the injury [2]. Shock waves are also known to damage the brain at the subcellular level, but exactly how remains unclear. Kato et al., [3] described the effects of a small controlled explosion on rats’ brain tissue. They found that high pressure shock waves led to contusions and hemorrhage in both cortical and subcortical brain regions. Based on their result, the threshold for shock wave-induced brain injury is speculated to be under 1 MPa. This is the first report to demonstrate the pressure-dependent effect of shock wave on the histological characteristics of brain tissue. An important step in understanding the primary blast injury mechanism due to explosion is to translate the global head loads to the loading conditions, and consequently damage, of the cells at the local level and to project cell level and tissue level injury criteria towards the level of the head. In order to reach this aim, we have developed a multi-scale non-linear finite element modeling to bridge the micro- and macroscopic scales and establish the connection between microstructure and effective behavior of brain tissue to develop acceptable injury threshold. Part of this effort has been focused on measuring the shock waves created from a blast, and studying the response of the brain model of a human head exposed to such an environment. The Arbitrary Lagrangian Eulerian (ALE) and Fluid/Solid Interactions (FSI) formulation have been used to model the brain-blast interactions. Another part has gone into developing a validated fiber-matrix based micro-scale model of a brain tissue to reproduce the effective response and to capturing local details of the tissue’s deformations causing axonal injury. The micro-model of the axon and matrix is characterized by a transversely isotropic viscoelastic material and the material model is formulated for numerical implementation. Model parameters are fit to experimental frequency response of the storage and loss modulus data obtained and determined using a genetic algorithm (GA) optimizing method. The results from macro-scale model are used in the micro-scale brain tissue to study the effective behavior of this tissue under injury-based loadings. The research involves the development of a tool providing a better understanding of the mechanical behavior of the brain tissue against blast loads and a rational multi-scale approach for driving injury criteria.

Scaling up microbial dynamics for soil carbon cycling models

2020 ◽  
Author(s):  
Stefano Manzoni ◽  
Arjun Chakrawal ◽  
Naoise Nunan
Keyword(s):  
Soil Heterogeneity ◽  
Scale Model ◽  
Soil Drying ◽  
Integration Step ◽  
Soil Core ◽  
Microbial Dynamics ◽  
Element Cycling ◽  
Micro Scale ◽  
Macro Scale ◽  
Soil Heterogeneities

<p>Soils are heterogeneous at all scales and so are the biogeochemical reactions driving the cycling of carbon (C) and nutrients in soils. While the microbial processes involved in these reactions occur at the pore scale, what we observe at the soil core or pedon scale depends on how micro-scale processes are integrated in space (and time). This integration step requires accounting for the inherent patchiness of soils, but models used to describe element cycling in soils typically assume that conditions are well-mixed and that kinetics laws developed for laboratory conditions hold. Similarly, the response functions used in models to capture the effects of environmental conditions on C and nutrient fluxes neglect the contribution of spatial heterogeneities, which might alter their shape. There is therefore a need to re-evaluate model structures to test whether they can account for micro-scale heterogeneities. Alternatively, one can ask why some models are clearly successful in capturing observations despite neglecting soil heterogeneities. In this contribution, we present examples of how soil heterogeneities – in particular the spatial placement of soil microorganisms and their substrate – may affect decomposition kinetics and microbial responses to soil drying. We show that the kinetics laws used in current models are different from the kinetics obtained by integrating microbial dynamics at the micro-scale, and that respiration responses to soil drying may vary depending on soil heterogeneity. These results thus highlight structural uncertainties in current models that we propose can be assessed using existing ‘scale-aware’ methods to derive macro-scale model formulations. Model advances will need to be supported by empirical evidence bridging the gap between pore and core (or larger) scales, but can also provide new theory-based hypotheses for novel experiments.</p>

MD-ISE-FE Multiscale Modeling and Numerical Simulation of Thermal Conductivity of Cu Film Interface Structure

2011 ◽  
Vol 382 ◽  
pp. 242-246 ◽  
Author(s):  
Li Qiang Zhang ◽  
Ping Yang ◽  
Fang Wei Xie ◽  
Tao Xi ◽  
Xin Gang Yu ◽  
...  
Keyword(s):  
Interface Structure ◽  
Scale Model ◽  
Interface Element ◽  
Multi Scale ◽  
Nano Scale ◽  
Cu Film ◽  
Macro Scale ◽  
Sequential Coupling ◽  
Properties Of Materials ◽  
Eam Potential

With the devices miniaturization, the properties of materials at the micro/nano scale were much different from what at Macro-scale because of the scale effect. The Interface Stress Element (ISE) was introduced into the multi-scale model. These three methods, Molecular Dynamics (MD), ISE and Finite Element (FE) were effectively combined by designing a handshake region and using the transition interface element method. The multi-scale model of film was built based on MD-ISE-FE. The sequential coupling method was used to calculate, and then, the results of the FE and ISE region were applied to the MD region. The EAM potential was used to simulate. The results were the basically same with the other experimental and simulation results in the reference. It indicated that the multi-scale analysis method could be applied to calculate the thermodynamics properties of the interface structure at the Micro/nano scale.

Sign in / Sign up

Export Citation Format

Share Document