scholarly journals Vibration Induced by Moving Cranes in High-Tech Buildings due to Rail Pad Materials

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
S. H. Ju ◽  
H. H. Kuo ◽  
S. H. Ni
Keyword(s):  
Finite Element ◽  
Displacement Field ◽  
Degrees Of Freedom ◽  
Laboratory Experiments ◽  
Low Cost ◽  
High Tech ◽  
Full Model ◽  
Finite Element Analyses ◽  
Two Degrees Of Freedom ◽  
Low Stiffness

In this work, an appropriate rail pad is proposed to reduce the vibration induced by moving cranes near the source location in high-tech buildings. Using a simple two-degrees-of-freedom model and laboratory experiments, we found that a low-cost rubber pad is effective to reduce crane-induced vibration. A number of finite element analyses with the full model are then performed for a high-tech factory and a moving crane. The results show that a decrease in the stiffness of the rail pad can decrease crane-induced vibration, and it is obvious that the proposed low-stiffness rubber rail pad with significant damping is an appropriate material to reduce crane-induced vibration by as much as five dB. In addition, the displacement field using the rubber pad is still much smaller than 2 mm, which is the working requirement for moving cranes.

A New Stress-Intensity Factor Solution for an External Surface Crack in Spheres

2021 ◽  
Author(s):  
James C. Sobotka ◽  
Yi-Der Lee ◽  
Joseph W. Cardinal ◽  
R. Craig McClung
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Crack Front ◽  
Surface Crack ◽  
Degrees Of Freedom ◽  
External Surface ◽  
Crack Plane ◽  
Finite Element Analyses ◽  
Stress Variations ◽  
Geometric Formulation

Abstract This paper describes a new stress-intensity factor (SIF) solution for an external surface crack in a sphere that expands capabilities previously available for this common pressure vessel geometry. The SIF solution employs the weight function (WF) methodology that enables rapid calculations of SIF values. The WF methodology determines SIF values from the nonlinear stress variations computed for the uncracked geometry, e.g., from service stresses and/or residual stresses. The current approach supports two degrees of freedom that denote the two crack tips located normal to the surface and the surface of the sphere. The geometric formulation of this solution enforces an elliptical crack front, maintains normality of the crack front with the free surface, and supports two degrees of freedom for fatigue crack growth from an internal crack tip and a surface crack tip. The new SIF solution accommodates spherical geometries with an exterior diameter greater than or equal to four times the thickness. This WF SIF solution has been combined with stress variations common for spherical pressure vessels: uniform internal pressure on the interior surface, uniform tension on the crack plane, and uniform bending on the crack plane. This paper provides a complete overview of this solution. We present for the first time the geometric formulation of the crack front that enables the new functionality and set the geometric limits of the solution, e.g., the maximum size and shape of the crack front. The paper discusses the bivariant WF formulation used to define the SIF solution and details the finite element analyses employed to calibrate terms in the WF formulation. A summary of preliminary verification efforts demonstrates the credibility of this solution against independent results from finite element analyses. We also compare results of this new solution against independent SIFs computed by finite element analyses, legacy SIF solutions, API 579, and FITNET. These comparisons indicate that the new WF solution compares favorably with results from finite element analyses. This paper summarizes ongoing efforts to improve and extend this solution, including formal verification and development of an internal surface crack model. Finally, we discuss the capabilities of this solution’s implementation in NASGRO® v10.0.

A Local Refinement Technique for B-Spline Finite Element Shell Modeling

2013 ◽  
Author(s):  
Antonio Carminelli ◽  
Giuseppe Catania
Keyword(s):  
Finite Element ◽  
Displacement Field ◽  
Degrees Of Freedom ◽  
Natural Frequencies ◽  
Element Model ◽  
Complex Structures ◽  
Local Refinement ◽  
B Spline ◽  
Spline Finite Element ◽  
Shell Finite Element

This paper presents a refinement technique for a B2-spline degenerate isoparametric shell finite element model for the analysis of the vibrational behavior of thin and moderately thick-walled structures. Complex structures to be refined are modeled by means of FE B-spline patches assembled with C0 continuity as usual in FE technique. The model refinement was performed by adding, on the domain of the selected patch, a tensorial set of polynomial B-spline functions, defined on local clamped knot vectors, and normalizing all the functions so that the resulting displacement field remain polynomial and continuous overall the domain except on the boundaries of the refined subdomain. A degrees of freedom trasformation, based on the knot-insertion algorthim, is adopted in order to guarantee the C0 continuity of the displacement field on the boundaries of the refined subdomain. Two numerical examples are presented in order to test the proposed approach. The natural frequencies of two structures, computed by means of the proposed modelling technique, are compared with reference results available in the literature or computed by means of reference standard FE models. Strengths and limits of the approach are finally discussed.

scholarly journals On a bending problem of thick laminated composite plates

2002 ◽  
Vol 24 (1) ◽  
pp. 35-45
Author(s):  
Ngo Nhu Khoa ◽  
Ngo Ich Thinh
Keyword(s):  
Finite Element ◽  
Closed Form ◽  
Displacement Field ◽  
Degrees Of Freedom ◽  
Laminated Composite ◽  
Composite Plates ◽  
Layered Composite ◽  
Laminated Composite Plates ◽  
Quadrilateral Element ◽  
Transverse Loads

A high-order displacement field in quadrilateral element with nine nodes and twelve-degrees-of-freedom per node is developed for bending analysis of thick arbitrary layered composite plates under transverse loads. Results for plate deformations, internal stress-resultants and stresses for selected examples are shown to compare well with the closed-form and other finite element solutions.

A formulation of membrane finite elements with true drilling rotation

2019 ◽  
Vol 37 (1) ◽  
pp. 203-236 ◽  
Author(s):  
Djamel Boutagouga
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Displacement Field ◽  
Degrees Of Freedom ◽  
Polynomial Interpolation ◽  
Normal Displacement ◽  
Geometric Transformation ◽  
Rotational Degree ◽  
Content Type ◽  
Corner Node

Purpose This paper aims to describe the formulation of a displacement-based triangular membrane finite element with true drilling rotational degree of freedom (DOF). Design/methodology/approach The presented formulation incorporates the true drilling rotation provided by continuum mechanics into the displacement field by way of using the polynomial interpolation. Unlike the linked interpolation, that uses a geometric transformation between displacement and vertex rotations, in this work, the interpolation of the displacement field in terms of nodal drilling rotations is obtained following an unusual approach that does not imply any presumed geometric transformation. Findings New relationship linking the mid-side normal displacement to corner node drilling rotations is derived. The resulting new element with true drilling rotation is compatible and does not include any problem-dependent parameter that may influence the results. The spurious zero-energy mode is stabilized in a careful way that preserves the true drilling rotational degrees of freedom (DOFs). Originality/value Several works dealing with membrane elements with vertex rotational DOFs have been published with improved convergence rate, however, owing to the need for incorporating rotations in the finite element meshes involving solids, shells and beam elements, having finite elements with true drilling rotational DOFs is more appreciated.

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.

Enhancements to AMB Force Measurement Procedures for Application to a Rocket Thrust Measurement System

2000 ◽  
Author(s):  
Joe Imlach ◽  
Mary E. F. Kasarda ◽  
P. A. Balaji
Keyword(s):  
Finite Element ◽  
Measurement System ◽  
Degrees Of Freedom ◽  
Force Measurement ◽  
Calibration Procedure ◽  
Magnetic Bearings ◽  
Finite Element Analyses ◽  
Thrust Measurement ◽  
On Line ◽  
Rocket Thrust

Active Magnetic Bearings (AMBs) can be used concurrently as support bearings and as load cells for the measurement of support forces. This paper discusses the preliminary design for a test rig to simulate a full-scale rocket thrust measurement system utilizing AMBs and procedures that have been developed to enhance the use of AMBs in this application. These enhancements include the development of a model of the effect of fringing on force measurements and an on-line calibration procedure. The fringing effect model is based on actuator geometry and has been verified through finite element analyses. On-line calibration procedures for a magnetic thrust bearing arrangement have also been developed and verified through finite element analyses. Since the rocket thrust measurement system is not rotating, planar magnetic bearings will also be used for vertical support and will utilize the same calibration procedure, resulting in force and torque measurements in all six degrees of freedom.

scholarly journals Design and Accuracy Analysis of a Micromachine Tool with a Co-Planar Driving Mechanism

2021 ◽  
Vol 11 (3) ◽  
pp. 947
Author(s):  
Shih-Ming Wang ◽  
Zhe-Zhi Ye ◽  
Hariyanto Gunawan
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
High Accuracy ◽  
High Tech ◽  
Driving Mechanism ◽  
Control Analysis ◽  
Error Sources ◽  
High Feed ◽  
Optimal Accuracy ◽  
Cutting Experiments

Due to the requirements of manufacturing miniaturized high-tech products, micromachining with micromachine tools has come to be regarded as an important technology. The main goal of this study is to build up the key technologies, including optimal structure and configuration design, synchronous driving control, analysis of optimal accuracy, in order to develop a low-cost and high-accuracy micromachine tool with a multi-degrees of freedom (DOF) platform with a co-plane synchronous driving mechanism. Due to the advantages of such a mechanism, the machine is able to possess a high feed resolution and high accuracy without the use of expensive drive components and high-end CNC controllers. Because of the no pile-up structure, the machine has less movement inertia effect, as well as the merits of light weight, high stiffness, and increased stability. Furthermore, the machine has more DOF, resulting in a better cutting performance than that of 3-DOF machine tools. To better understand the characteristics of major error sources of the machine in order to further enhance its accuracy, hybrid error analysis, kinematics analysis, and a volumetric error model were conducted. Finally, a prototype of the designed micromachine tool was built, and cutting experiments for accuracy calibration and verification were carried out using this machine. The results showed that the machine was able to effectively execute 4-DOF microcutting with positioning accuracy of 800 nm.

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