Combined empirical–analytical method for determining contact radius and indenter displacement during Hertzian indentation on coating/substrate systems

2004 ◽  
Vol 19 (9) ◽  
pp. 2774-2781 ◽  
Author(s):  
Chun-Hway Hsueh ◽  
Pedro Miranda
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Empirical Equation ◽  
Contact Radius ◽  
Finite Element Analyses ◽  
Modulus Ratio ◽  
Properties Of Coatings ◽  
Hertzian Indentation ◽  
Potential Applications

An analytical model was developed in a previous work to relate the normalized indenter displacement to both the coating-to-substrate Young's modulus ratio and the coating-thickness-to-contact-radius ratio for Hertzian indentation on coating/substrate systems. However, application of this model is contingent upon the determination of the contact radius during indentation. Using the data from finite element analyses, an empirical equation is proposed in this paper to determine the normalized contact radius. Combining this empirical equation with the previous analytical equation, both the contact radius and the indenter displacement for Hertzian indentation on coating/substrate systems are predicted. The predictions obtained by this combined empirical–analytical method are shown to agree with the finite element results in general although the indenter displacement is over-estimated when the coating is stiffer than the substrate. Finally, the potential applications of this method to determine the elastic properties of coatings from the indentation data are envisaged.

Master curves for Hertzian indentation on coating/substrate systems

2004 ◽  
Vol 19 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Chun-Hway Hsueh ◽  
Pedro Miranda
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Coating Thickness ◽  
Closed Form Solution ◽  
Form Solution ◽  
Contact Radius ◽  
Finite Element Analyses ◽  
Master Curves ◽  
Modulus Ratio ◽  
Hertzian Indentation

An analytical model was developed to derive an approximate closed-form solution for indenter displacement when a rigid spherical indenter is pressed onto a coating/substrate system. Finite element analyses were also performed to verify the analytical solution. The results showed that the solution could be obtained from the analytical expression for Hertzian indentation on a homogeneous semi-infinite elastic medium multiplied by a modification term. This modification term is a function of two ratios: (i) Young’s modulus ratio between the coating and the substrate and (ii) the ratio between the coating thickness and the contact radius. Based on this modification term, master curves for Hertzian indentation on coating/substrate systems were plotted.

Study of bolted joint axial stiffness using finite element analyses, experimental tests, and analytical calculations

2020 ◽  
Vol 234 (23) ◽  
pp. 4671-4681
Author(s):  
Raphael Calazans Cardoso ◽  
Brenno Lima Nascimento ◽  
Felipe de Freitas Thompson ◽  
Sandro Griza
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
High Reliability ◽  
Experimental Tests ◽  
Bolted Joints ◽  
Axial Stiffness ◽  
Bolted Joint ◽  
Finite Element Analyses ◽  
Load Distributions ◽  
Reliable Design

The bolted joints sizing procedures shall adequately match the conditions imposed on the joint in service, to ensure high reliability designs. Therefore, this study aims to analyze the load distributions on the bolt when applying external load on bolted joints. Finite element and extensometry analyses as well as analytical calculations were performed in order to compare the magnitude of the joint overall stiffness, with respect to several available theories. The results acquired through the analytical method prescribed in the VDI 2230 standard as well as the finite element and extensometry analyses obtained great accordance. These results indicate that VDI 2230 standard adequately represents the mechanical behavior of the joint and should be used as a guideline for the reliable design of bolted joints subjected to the loading conditions of the present paper.

Constraint Solutions for Cracked Plates and Cylinders

2016 ◽  
Author(s):  
Caroline Meek ◽  
Marius Gintalas ◽  
Andrew H. Sherry ◽  
Robert A. Ainsworth
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Biaxial Loading ◽  
Analytical Determination ◽  
Plastic Collapse ◽  
Finite Element Analyses ◽  
Elastic Plastic ◽  
Cracked Plates ◽  
Computing Effort

There is little advice in fitness for service procedures for assessing constraint parameters T (elastic) and Q (elastic plastic) for biaxially loaded plates and cylinders. This paper presents the analytical determination of T stresses for biaxially loaded plates and the determination of Q for plates and cylinders using finite element analyses. It demonstrates the extent to which T can be used to conservatively predict Q and how, near collapse, Q can be estimated from the stress field corresponding to plastic collapse, enabling a significant reduction in computing effort. The effect of biaxial loading of plates and cylinders on these parameters is discussed as well as the differences found when comparing the values for plates and cylinders.

scholarly journals A method for handlebars ballast calculation in order to reduce vibrations transmissibility in walk behind tractors

2017 ◽  
Vol 48 (2) ◽  
pp. 81 ◽  
Author(s):  
Angelo Fabbri ◽  
Chiara Cevoli ◽  
Giuseppe Cantalupo
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Experimental Tests ◽  
Dynamic Structure ◽  
Average Percentage ◽  
Percentage Difference ◽  
Average Percentage Difference ◽  
Vibration Transmissibility ◽  
High Level

Walk behind tractors have some advantages over other agricultural machines, such as the cheapness and the easy to use, however the driver is exposed to high level of vibrations transmitted from handles to hand-arm system and to shoulders. The vibrations induce discomfort and early fatigue to the operator. In order to control the vibration transmissibility, a ballast mass may be added to the handles. Even if the determination of the appropriate ballast mass is a critical point in the handle design. The aim of this research was to study the influence of the handle mass modification, on the dynamic structure behaviour. Modal frequencies and subsequent transmissibility calculated by using an analytical approach and a finite elements model, were compared. A good agreement between the results obtained by the two methods was found (average percentage difference calculated on natural frequencies equal to 5.8±3.8%). Power tillers are made generally by small or medium-small size manufacturers that have difficulties in dealing with finite element codes or modal analysis techniques. As a consequence, the proposed analytical method could be used to find the optimal ballast mass in a simple and economic way, without experimental tests or complex finite element codes. A specific and very simple software or spreadsheet, developed on the base of the analytical method here discussed, could effectively to help the manufacturers in the handlebar design phase. The choice of the correct elastic mount, the dimensioning of the guide members and the ballast mass could be considerably simplified.

Industrial Application of the Method “Early Determination of Product Properties”

1998 ◽  
Author(s):  
Udo Lindemann ◽  
Ralf Stetter
Keyword(s):  
Finite Element ◽  
Product Development ◽  
Development Process ◽  
Product Development Process ◽  
Complex Method ◽  
Finite Element Analyses ◽  
Negative Effects ◽  
Influencing Parameters ◽  
Industrial Company

Abstract Nothing is more critical for the success of a project than a design flaw that remains undetected until the product is in production or even handed over to the customer. In order to prevent the negative effects of undetected flaws, the method “early determination of product properties” has been developed at the Chair of Design at the Technische Universität München. In this paper the introduction of the method in a mid-size industrial company and the first resulting tool, the Parameter Checklist, are described. The presented research started with a detailed analysis of the product development process in the industrial company. In order to introduce a complex method in an industrial company, many aspects of the situation of the designers, from existing tools and procedures to the designers’ capabilities have to be considered. Because of this, the method was divided into distinct ideas, stages and tools, and compared individually to the situation given. On this basis a first methodical tool was developed, intended to support designers while using the method. The tool called Parameter Checklist supports designers in planning analyses (e.g. tests with physical prototypes, finite element analyses) and in interpreting the results of these analyses. Furthermore, by using the tool, a database is filled that provides enough information to reconstruct the described analyses. In contrast with conventional testing instructions, the Parameter Checklist contains an explicit description of the model, in some respects found to be important, and a list of the influencing parameters. This is the basis for both a simple but conscious form of analysis planning and a more thorough interpretation of the analysis results.

scholarly journals Optimum Design of Sunken Reinforced Enclosures under Buckling Condition

2020 ◽  
Vol 10 (23) ◽  
pp. 8449
Author(s):  
Mostafa Omidi Bidgoli ◽  
Kazem Reza Kashyzadeh ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů ◽  
Nima Amiri
Keyword(s):  
Finite Element ◽  
Critical Load ◽  
Optimum Design ◽  
Analytical Method ◽  
Design Principles ◽  
Offshore Structures ◽  
Finite Element Analyses ◽  
Marine Structures ◽  
Minimum Thickness ◽  
Good Agreement

Increasing the lifetime and improving the performance of structures through redesign and optimization are important, especially in marine structures. In general, there are two main groups of marine structures: onshore and offshore structures. Most marine structures are offshore, and these are divided into two categories: floating or sunken. One of the important parameters in the design of sunken structures is the critical load resulting from the buckling of walls, which can cause damage to the structure. In the present paper, three rectangular aluminum and steel compartments of different conditions and sizes were modeled using design analysis methods. Then, different finite element analyses were performed, and the compartments were optimized to reduce the weight of the structure. Finally, the buckling results of three types of rectangular reinforced compartments were calculated and were compared with each other. The results show that the stresses calculated using the analytical method are in good agreement with the results of the finite element analyses. In addition, the weight of the compartment is reduced by utilizing the reinforced conductors in accordance with the design principles and considering the minimum thickness.

Substrate-affected indentation contact parameters of elastoplastic coating/substrate composites

2009 ◽  
Vol 24 (3) ◽  
pp. 831-843 ◽  
Author(s):  
Mototsugu Sakai
Keyword(s):  
Finite Element ◽  
Strain Field ◽  
Constitutive Relationship ◽  
Contact Radius ◽  
Spatial Confinement ◽  
Composite Systems ◽  
Theoretical Predictions ◽  
Relationship Of ◽  
Contact Parameters

In coating/substrate bilayer systems, the indentation contact behavior transitionally varies from coatinglike to substratelike behaviors. Spatial confinement effects of the substrate induce very complicated plastic flows in the coating beneath the indenter, leading to a crucial difficulty that is not accounted for by any of the present quantitative analytical/theoretical predictions for the substrate-affected contact hardness. In this work, the author presents finite-element-based studies on the elastoplastic indentation contact mechanics of coating/substrate systems. The effect of the substrate is taken into account by introducing the spatially variable elastic modulus and the yield stress; this approach quantitatively describes the substrate-affected stress/strain field in the spatially localized area beneath the indenter. The elastoplastic constitutive relationship of the contact hardness for semi-infinite homogeneous bulks combined with these spatially variable material characteristics are successfully applied to analytically as well as quantitatively predict the substrate-affected contact hardness of bilayer composite systems having wide ranges of elastoplastic coating/substrate characteristics. The experimental procedures for determining the elastic/plastic parameters both of the coating and the substrate are also discussed, in which the importance of the experimental determination of substrate-affected indentation contact radius/area is emphasized.

Parametric finite element analyses of geocell-supported embankments

2007 ◽  
Vol 44 (8) ◽  
pp. 917-927 ◽  
Author(s):  
G. Madhavi Latha ◽  
K. Rajagopal
Keyword(s):  
Finite Element ◽  
Laboratory Experiments ◽  
Empirical Equation ◽  
Tensile Modulus ◽  
Confining Pressure ◽  
Composite Model ◽  
Finite Element Analyses ◽  
Numerical Studies ◽  
Strength And Stiffness ◽  
Geocell Reinforcement

This paper presents the results from parametric finite element analyses of geocell-supported embankments constructed on weak foundation soils. A composite model is used to numerically simulate the improvement in the strength and stiffness of the soil as a result of geocell confinement. The shear strength of the geocell-encased soil is obtained as a function of the additional confining pressure due to the geocell encasement considering it as a thin cylinder subjected to internal pressure. The stiffness of the geocell-encased soil is obtained from the stiffness of the unreinforced soil and the tensile modulus of the geocell material using an empirical equation. The validity of the model is verified by simulating the laboratory experiments on model geocell-supported embankments. Parametric finite element analyses of the geocell-supported embankments are carried out by varying the dimensions of the geocell layer, the tensile strength of the material used for fabricating the geocell layer, the properties of the infill soil, and the depth of the foundation layer. Some important guidelines for selecting the geocell reinforcement to support embankments on weak foundation soils are established through these numerical studies.

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