scholarly journals Modeling of the buckstay system of membrane-walls in watertube boiler construction

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 59-72 ◽  
Author(s):  
Hasan Nagiar ◽  
Tasko Maneski ◽  
Vesna Milosevic-Mitic ◽  
Branka Gacesa ◽  
Nina Andjelic
Keyword(s):  
Finite Element ◽  
Orthotropic Plate ◽  
Global Model ◽  
Local Model ◽  
Thermal Loads ◽  
Water Tube ◽  
Bending Load ◽  
Specific Geometry ◽  
Structural Parts ◽  
Help Model

Membrane walls are very important structural parts of water-tube boiler construction. Based on their specific geometry, one special type of finite element was defined to help model the global boiler construction. That is the element of reduced orthotropic plate with two thicknesses and two elasticity matrixes, for membrane and bending load separately. A global model of the boiler construction showed that the high value of stress is concentrated in plates of the buckstay system in boiler corners. Validation of the new finite element was done on the local model of the part of membrane wall and buckstay. A very precise model of tubes and flanges was compared to the model formed on the element of a reduced orthotropic plate. Pressure and thermal loads were discussed. Obtained results indicated that the defined finite element was quite favorable in the design and reconstruction of the boiler substructures such as a buckstay system.

Finite element modeling of underground water flow with Ranney wells

2007 ◽  
Vol 7 (3) ◽  
pp. 41-50 ◽  
Author(s):  
M. Kojić ◽  
N. Filipović ◽  
B. Stojanović ◽  
V. Ranković ◽  
M. Krstić ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Boundary Conditions ◽  
Water Flow ◽  
Groundwater Resources ◽  
Underground Water ◽  
Global Model ◽  
Local Model ◽  
Fe Model ◽  
Surface Boundary

The objectives of this study were to define the regional and local groundwater flow, and to give quantitative estimates of the groundwater dynamic parameters and of the available groundwater resources. To achieve these objectives, numerical tools are required to quantitatively model flow through porous saturated and unsaturated media. We have developed a general finite element (FE) model for underground water flow and specific algorithms for Ranney wells. Solutions for steady and unsteady conditions are obtained by using two basic models: global and local. The global model consists of 3D finite elements and 1D finite elements with the equivalent well permeability representing Ranney wells. The local models are generated around wells, using solutions for all quantities from 3D global model at a cylindrical surface which bounds the local model. The local model consists of a fine 3D FE mesh and 1D elements used to model each of the well screens. We developed a software for pre- and post-processing, Lizza, which can be used for easy modeling of complex engineering underground water flow problems with Ranney wells. The FE package PAK-P is used as the solver. This software can handle flow regions with general irregular boundaries. The flow region itself may be composed of layers of nonuniform soils having an arbitrary degree of local anisotropy. Flow can occur in the vertical plane, the horizontal plane, or in a three dimensional region exhibiting radial symmetry about the vertical axis. The water flow model includes constant or time-varying prescribed head and flux boundaries, as well as boundaries controlled by atmospheric conditions. At a soil surface, boundary conditions may change during the time evolution from prescribed flux to prescribed head type conditions (and vice versa). The model also include a seepage face boundary through which water leaves the saturated part of the flow domain, and free drainage boundary conditions. The results of modeling several real engineering projects (Belgrade Water Supply Center) are presented.

The influence of infill density gradient on the mechanical properties of PLA optimized structures by additive manufacturing

2021 ◽  
pp. 146442072110071
Author(s):  
AIL Pais ◽  
C Silva ◽  
MC Marques ◽  
JL Alves ◽  
J Belinha
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Additive Manufacturing ◽  
Structural Optimization ◽  
Meshless Method ◽  
Load Case ◽  
Fused Filament Fabrication ◽  
Ductile Metals ◽  
Four Point Bending ◽  
Bending Load

The aim of this work is the development of a novel framework for structural optimization using bio-inspired remodelling algorithm adapted to additive manufacturing. The fact that polylactic acid (PLA, E = 3145 MPa (Young’s modulus) according to the supplier for parts obtained by injection) shows a similar parameterized behavior with ductile metals, in the sense that both materials are characterized by a bi-linear elastic-plastic law, allows to simulate and prototype parts to be further constructed in ductile metals at a lower cost and then be produced with more expensive fabrication processes. Moreover, cellular materials allow for a significant weight reduction and therefore reduction of production costs. Structural optimization algorithms based on biological phenomena were used to determine the density distribution of the infill density of the specimens. Several simple structures were submitted to distinct complex load cases and analyzed using the mentioned optimization algorithms combined with the finite element method and a meshless method. The surface was divided according to similar density and then converted to stereolitography files and infilled with the gyroid structure at the desired density determined before, using open-source slicing software. Smoothing functions were used to smooth the density field obtained with the remodeling algorithms. The samples were printed with fused filament fabrication technology and submitted to mechanical flexural tests similar to the ones analyzed analytically, namely three- and four-point bending tests. Thus, the factors of analysis were the smoothing parameter and the remodeling method, and the responses evaluated were stiffness, specific stiffness, maximum force, and mass. The experimental results correlated (obtaining accuracy of 35% for the three-point bending load case and 5% for the four-point bending load case) to the numerical results in terms of flexural stiffness and it was found that the complexity of the load case is relevant for the efficiency of the functional gradient. The fused filament fabrication process is still not accurate enough to be able to experimentally compare the results based of finite element method and meshless method analyses.

Modeling the HSK Toolholder-Spindle Interface

2002 ◽  
Vol 124 (3) ◽  
pp. 734-744 ◽  
Author(s):  
Ihab M. Hanna ◽  
John S. Agapiou ◽  
David A. Stephenson
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
System Reliability ◽  
High Volume ◽  
Finite Element Models ◽  
Operational Experience ◽  
Bending Load ◽  
Load Carrying ◽  
Detailed Evaluation ◽  
Contact Pressures

The HSK toolholder-spindle connection was developed to overcome shortcomings of the 7/24 steep-taper interface, especially at higher speeds. However, the HSK system was standardized quickly, without detailed evaluation based on operational experience. Several issues concerning the reliability, maintainability, and safety of the interface have been raised within the international engineering community. This study was undertaken to analytically investigate factors which influence the performance and limitations of the HSK toolholder system. Finite Element Models were created to analyze the effects of varying toolholder and spindle taper geometry, axial spindle taper length, drawbar/clamping load, spindle speed, applied bending load, and applied torsional load on HSK toolholders. Outputs considered include taper-to-taper contact pressures, taper-to-taper clearances, minimum drawbar forces, interface stiffnesses, and stresses in the toolholder. Static deflections at the end of the holder predicted by the models agreed well with measured values. The results showed that the interface stiffness and load-carrying capability are significantly affected by taper mismatch and dimensional variations, and that stresses in the toolholder near the drive slots can be quite high, leading to potential fatigue issues for smaller toolholders subjected to frequent clamping-unclamping cycles (e.g., in high volume applications). The results can be used to specify minimum toolholder material properties for critical applications, as well as drawbar design and spindle/toolholder gaging guidelines to increase system reliability and maintainability.

Experimental Characterization and Finite Element Modeling of Film Capacitors for Automotive Applications

2016 ◽  
Author(s):  
D. Croccolo ◽  
T. M. Brugo ◽  
M. De Agostinis ◽  
S. Fini ◽  
G. Olmi
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
High Reliability ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Life Time ◽  
Element Model ◽  
Image Correlation ◽  
Thermal Loads ◽  
Mechanical Shock

As electronics keeps on its trend towards miniaturization, increased functionality and connectivity, the need for improved reliability capacitors is growing rapidly in several industrial compartments, such as automotive, medical, aerospace and military. Particularly, recent developments of the automotive compartment, mostly due to changes in standards and regulations, are challenging the capabilities of capacitors in general, and especially film capacitors. Among the required features for a modern capacitor are the following: (i) high reliability under mechanical shock, (ii) wide working temperature range, (iii) high insulation resistance, (iv) small dimensions, (v) long expected life time and (vi) high peak withstanding voltage. This work aims at analyzing the key features that characterize the mechanical response of the capacitor towards temperature changes. Firstly, all the key components of the capacitor have been characterized, in terms of strength and stiffness, as a function of temperature. These objectives have been accomplished by means of several strain analysis methods, such as strain gauges, digital image correlation (DIC) or dynamic mechanical analysis (DMA). All the materials used to manufacture the capacitor, have been characterized, at least, with respect to their Young’s modulus and Poisson’s ratio. Then, a three-dimensional finite element model of the whole capacitor has been set up using the ANSYS code. Based on all the previously collected rehological data, the numerical model allowed to simulate the response in terms of stress and strain of each of the capacitor components when a steady state thermal load is applied. Due to noticeable differences between the thermal expansion coefficients of the capacitor components, stresses and strains build up, especially at the interface between different components, when thermal loads are applied to the assembly. Therefore, the final aim of these numerical analyses is to allow the design engineer to define structural optimization strategies, aimed at reducing the mechanical stresses on the capacitor components when thermal loads are applied.

Local model of a scientific collaboration in physics network compared with the global model

2010 ◽  
Vol 389 (23) ◽  
pp. 5530-5537 ◽  
Author(s):  
A.A. Roohi ◽  
A.H. Shirazi ◽  
A. Kargaran ◽  
G.R. Jafari
Keyword(s):  
Scientific Collaboration ◽  
Global Model ◽  
Local Model

The Evolution of Contact Stress and Surface Profile in Press-Fitted Shaft under Partial Slip Conditions

2006 ◽  
Vol 321-323 ◽  
pp. 1495-1498 ◽  
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Chan Woo Lee ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Surface Profile ◽  
Contact Stresses ◽  
Fretting Wear ◽  
Partial Slip ◽  
Initial Surface ◽  
Slip Conditions ◽  
Bending Load ◽  
Element Method

In this paper the fretting wear of press-fitted specimens under partial slip conditions was simulated using finite element method and numerical analysis based on Archard's equation. An elasto-plastic analysis of contact stresses in a press-fitted shaft in contact with a boss was conducted with finite element method and the amount of microslip and contact pressure due to bending load was estimated. The predicted wear profile of press-fitted specimens at the contact edge was compared with the experimental results. It is found that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact stresses and strain are redistributed.

scholarly journals Numerical Simulation on Reinforced Concrete Beam with Different Cover Size under Two Point Bending Load

2021 ◽  
Vol 7 (05) ◽  
pp. 39-43
Author(s):  
R Padma Rani & R Harshani
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Structural Analysis ◽  
Concrete Beam ◽  
Failure Modes ◽  
Equivalent Stress ◽  
Reinforced Concrete Beam ◽  
Simulation Software ◽  
Beam Specimen ◽  
Bending Load

Structural analysis is used to assess the behavior of engineering structures under the application of loads. Usually, structural analysis methods include analytical,experimental and numerical methods is used in thisproject, however, only Analytical method is used and the values are taken from literature reference, to get familiar with Finite Element Analysis (FEA) using ANSYS, this is done to acquire practical knowledge about of the effect of the cover. The aim is to identify different failure modes under a range of loading conditions by changing the cover size to get the data of various parameters such as deflection, stress etc. Study of cover helps to observe the stability, reliability and the overall strength of the structural beam. This project attempts made to study the effect of cover on the behavior of reinforced concrete beam. Forthis analytical study, the Reinforced concrete beam specimen of 2000x100x200mm was considered.ANSYS software is a suite of engineering simulation software, based on finite element method, which can solve problems ranging from linear analysis to nonlinear analysis. The Doubly reinforced beams weremodeled by using geometry. In this model,various covers are provided. The beam specimensused in this study were tested under two-point static loading condition until failure of the specimen. From theobtained resultconcluded that the total deformation and directional deformation values are low in 25mm cover compared to other cases but the equivalent stress value is low in 35mm cover size compared to 25mm cover size.

Modeling the HSK (Hollow Shank Taper 1/10 Tapered Joint) Toolholder-Spindle Interface

2000 ◽  
Author(s):  
Ihab M. Hanna ◽  
John S. Agapiou ◽  
David A. Stephenson
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
System Reliability ◽  
High Volume ◽  
Finite Element Models ◽  
Operational Experience ◽  
Bending Load ◽  
Load Carrying ◽  
Detailed Evaluation ◽  
Contact Pressures

Abstract The HSK toolholder-spindle connection was developed to overcome shortcomings of the 7/24 steep-taper interface, especially at higher speeds. However, the HSK system was standardized quickly, without detailed evaluation based on operational experience. Several issues concerning the reliability, maintainability, and safety of the interface have been raised within the international engineering community. This study was undertaken to analytically investigate factors which influence the performance and limitations of the HSK toolholder system. Finite Element Models were created to analyze the effects of varying toolholder and spindle taper geometry, axial spindle taper length, drawbar/clamping load, spindle speed, applied bending load, and applied torsional load on HSK toolholders. Outputs considered include taper-to-taper contact pressures, taper-to-taper clearances, minimum drawbar forces, interface stiffnesses, and stresses in the toolholder. Static deflections at the end of the holder predicted by the models agreed well with measured values. The results showed that the interface stiffness and load-carrying capability are significantly affected by taper mismatch and dimensional variations, and that stresses in the toolholder near the drive slots can be quite high, leading to potential fatigue issues for smaller toolholders subjected to frequent clamping-unclamping cycles (e.g., in high volume applications). The results can be used to specify minimum toolholder material properties for critical applications, as well as drawbar design and spindle/toolholder gaging guidelines to increase system reliability and maintainability.

An Evaluation and Comparison of Models for Maximum Deflection of Stiffened Plates Using Finite Element Analysis

2007 ◽  
Vol 44 (04) ◽  
pp. 212-225
Author(s):  
Lior Banai ◽  
Omri Pedatzur
Keyword(s):  
Finite Element ◽  
Orthotropic Plate ◽  
Lateral Pressure ◽  
Stiffened Plates ◽  
Maximum Deflection ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Element Analysis ◽  
The Past ◽  
Different Types

Stiffened plates form the backbone of most of a ship's structure. Today, finite element (FE) models are used to analyze the behavior of such structural elements for different types of loads. In the past, when usage of computers and FE models were not used very much, analytical analysis methods were required. Two well-known methods have been developed for analyses of stiffened plates under lateral loading (uniform pressure), based on two different models, namely, the orthotropic plate model and the grillage model. Both models can give estimations for the maximum plate deflection under uniform lateral pressure. The objective of this paper is to present the two methods, evaluate and compare the methods using the finite element method, and finally implement the methods as a computer program for quick estimations of the maximum deflection of stiffened plates. The degree of accuracy of the two methods when compared to FE is discussed in some detail.

Sign in / Sign up

Export Citation Format

Share Document