Impact on Beams

1936 ◽  
Vol 3 (2) ◽  
pp. A55-A61
Author(s):  
H. L. Mason
Keyword(s):  
Historical Development ◽  
Contact Region ◽  
Local Deformation ◽  
Lateral Vibration ◽  
Transverse Impact ◽  
Concentrated Mass ◽  
Impact Theory ◽  
Inelastic Impact ◽  
Maximum Contact

Abstract This paper deals with transverse impact on beams the mass of which is of importance. Experimental results are presented for comparison with theory. Impacts which appear single to the eye are shown to consist in reality of several blows in quick succession. Section 1 of the paper traces the historical development of this subject by discussing the investigations of Young, Hodgkinson, Cox, Saint Venant, and Timoshenko. Section 2 treats a simplified system in which a concentrated mass strikes a smaller concentrated mass having a “soft” spring restraint. For elastic impact, theory predicts for the struck mass a path composed of sinusoidal elements separated by instantaneous blows. For inelastic impact it predicts a joint harmonic motion. Records of the paths of both masses were obtained experimentally. Section 3 of the paper uses Timoshenko’s method of combining local deformation of the contact region with lateral vibration of the beam. An experimental investigation of maximum contact pressure and of blow duration gives what is believed to be the first confirmation of this theory. Section 4 describes an experimental determination of flexural stresses in elastic and inelastic impact on a 3-in. I-beam by the use of a Westinghouse magnetic strain gage. The indication is that stresses may be higher than those calculated by the usual approximations.

scholarly journals Enhancement of a New Methodology Based on the Impulse Excitation Technique for the Nondestructive Determination of Local Material Properties in Composite Laminates

2020 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Carlo Boursier Niutta
Keyword(s):  
Resonant Frequency ◽  
Elastic Properties ◽  
Composite Laminates ◽  
Concentrated Mass ◽  
Modal Shape ◽  
Nondestructive Determination ◽  
Material Orientation ◽  
Impulse Excitation ◽  
Clamping System

A new approach for the nondestructive determination of the elastic properties of composite laminates is presented. The approach represents an improvement of a recently published experimental methodology based on the Impulse Excitation Technique, which allows nondestructively assessing local elastic properties of composite laminates by isolating a region of interest through a proper clamping system. Different measures of the first resonant frequency are obtained by rotating the clamping system with respect to the material orientation. Here, in order to increase the robustness of the inverse problem, which determines the elastic properties from the measured resonant frequencies, information related to the modal shape is retained by considering the effect of an additional concentrated mass on the first resonant frequency. According to the modal shape and the position of the mass, different values of the first resonant frequency are obtained. Here, two positions of the additional mass, i.e., two values of the resonant frequency in addition to the unloaded frequency value, are considered for each material orientation. A Rayleigh–Ritz formulation based on higher order theory is adopted to compute the first resonant frequency of the clamped plate with concentrated mass. The elastic properties are finally determined through an optimization problem that minimizes the discrepancy on the frequency reference values. The proposed approach is validated on several materials taken from the literature. Finally, advantages and possible limitations are discussed.

An Analytical Description of the Magnetic Conductance Across an Isolated Defect Region in a 1D-Ferromagnetic Lead

SPIN ◽  
2019 ◽  
Vol 09 (01) ◽  
pp. 1950005 ◽  
Author(s):  
Adel Belayadi ◽  
Boualem Bourahla ◽  
Ahmed Mougari
Keyword(s):  
Contact Region ◽  
Analytical Description ◽  
Quantum Scattering ◽  
Defect Region ◽  
Model Calculations ◽  
Adopted Model ◽  
Field Matching ◽  
Ferromagnetic Lead ◽  
Transmission And Reflection

We illustrate in this contribution the determination of the magnetic conductance across a nanocontact region defined by an isolated defect region joined between two mono-atomic leads ferromagnetically ordered. The system is described by the Heisenberg interaction. Additionally, to deal with the lack of symmetry across the contact region defined by the isolated defect, we involve the phase field matching approach. Furthermore, to compute the quantum conductance, we define the quantum scattering of the transmission and reflection probabilities within the framework of Landauer–Büttiker formalism. Based on these approaches, we present an analytical expression of the magnetic conductance. The obtained analytical results based on our adopted procedures confirm the known results adopted for perfect infinite leads (no defect). Our model calculations can be applied numerically when we deal with doping across the defect region. The adopted model could be also used numerically to deal with the impurity configurations that one might encounter in real systems.

Determination of DC06+ZE Sheet Crack Cause

2016 ◽  
Vol 368 ◽  
pp. 121-125
Author(s):  
Pavel Kejzlar ◽  
Tomáš Pilvousek ◽  
Michal Tregler
Keyword(s):  
Stress Concentration ◽  
Tensile Stress ◽  
Deep Drawing ◽  
Crack Formation ◽  
Local Stress ◽  
Local Deformation ◽  
Local Stress Concentration ◽  
Bcc Lattice ◽  
Hard Particles

The present work deals with determination of the cause of crack occurring in a part of car body manufactured from deep-drawing sheet. UHR-SEM, EDS, EBSD and measurement of microhardness were used for evaluation of the structure, local deformation and crack formation mechanism. A material analysis discovered foreign particles in the material. These particles were identified as MgAl2O4 with BCC lattice. The occurrence of these hard particles led to local stress concentration, decrease in mechanical strength and sheet breach due to tensile stress during deformation.

scholarly journals Development of a three-parameter model of the shoe brake contact interaction with the drum in mine hoisting machine

2018 ◽  
Vol 60 ◽  
pp. 00039
Author(s):  
Kostiantyn Zabolotnyi ◽  
Oleksand Zhupiiev ◽  
Artur Molodchenko
Keyword(s):  
Contact Interaction ◽  
Accurate Determination ◽  
Mining Industry ◽  
Flexural Stiffness ◽  
Safe Operation ◽  
Translational Movement ◽  
Longitudinal Stiffness ◽  
The Coefficient Of Friction ◽  
Maximum Contact

For safe operation of mine hoisting machines (MHM) in the mining industry, it is necessary to provide high constructive reliability of brake systems, in particular, brake systems based on the block brake. The contact interaction of the brake with the translational movement of the shoes applied in MHM, remains insufficiently studied. In particular, it is necessary to develop a technique for accurate determination of the braking moment and forces in the elements of the brake linkage, as well as to study the nature of the pressure distribution along the brake beam. The purpose of this article is to simulate the contact interaction of the MHM brake taking into account the coefficient of friction, the ratio of the flexural stiffness to the longitudinal stiffness of a beam, as well as the ratio of the transverse stiffness of a lining to the flexural stiffness of a beam. The application of the developed model will help to reduce the maximum contact pressure in the shoe brakes of the mine hoisting machines and will allow more accurate calculation of the braking moment value compared to existing methods.

A Study of the Effect of m and n Coefficients of the Hertzian Contact Theory on Railroad Vehicle Dynamics

2007 ◽  
Author(s):  
J. P. Pascal ◽  
Khaled E. Zaazaa
Keyword(s):  
Contact Area ◽  
Contact Region ◽  
Local Deformation ◽  
Hertzian Contact ◽  
Vehicle Dynamic ◽  
Railroad Vehicle Dynamics ◽  
Original Table ◽  
Data Points ◽  
Railroad Vehicle ◽  
Contact Ellipse

For the wheel/rail contact problem, the Hertz theory for two elastic bodies in contact is commonly used to determine the shape and dimensions of the contact area and the local deformation of the wheel and rail surfaces at the contact region. The shape of the contact area is assumed to be elliptical. The ratio of the contact ellipse semi-axes is equal to the ratio of two non-dimensional contact area coefficients, known as m and n coefficients. Hertz presented a table of these two coefficients, determined as a function of an angular parameter, θ. Most railroad vehicle dynamic codes use this table with online interpolation to determine the contact ellipse semi-axes. Recently, it was found that this original table may be too coarse, and that more data points are needed within the table for solving the wheel/rail contact accurately. This paper discusses the effect of the accuracy of the m and n coefficients in solving for wheel/rail contact, and demonstrates this effect with two numerical examples that show the resulting differences in the dynamic behavior of railroad vehicles dependent on this accuracy. A new table with more data points is presented that is recommended for use in railroad vehicle dynamic codes that employ the Hertzian contact for solving the wheel/rail contact interaction. This modified table was originally derived by Jean-Pierre Pascal as a part of collaborative research between the Federal Railroad Administration (FRA) and the French Ministry of Transportation.

Reliability Design and Wear Extent Determination of a Cam Mechanism

2012 ◽  
Vol 268-270 ◽  
pp. 1034-1038
Author(s):  
Yi Yuan Ge ◽  
Jun Fa Wang ◽  
Gui Lian Wang ◽  
Ya Qin Li
Keyword(s):  
Fuzzy Optimization ◽  
Reliability Design ◽  
Cam Mechanism ◽  
Before And After ◽  
Base Circle ◽  
Important Field ◽  
Conventional Optimization ◽  
Maximum Contact ◽  
Mechanical Movement

The application of the cam mechanism is an important field in agricultural machinery since it can realize complex mechanical movement. The wear extent and action reliability of the cam affect the performance and accuracy of the mechanism. The paper combined reliability optimal design and tribology to build a fuzzy optimization model, with minimum of the cam base circle radius and minimum of the maximum contact stress as the objective functions. Compared with conventional optimization, the cam weight was reduced by 11.7%, the stress was increased by 1.96%, and the reliability increased 0.71%. Contrast tests were designed to determine the wear extent before and after optimization. The results prove the feasibility of optimization.

Determination of the boundary of a hydrodynamic contact region

1983 ◽  
Vol 23 (4) ◽  
pp. 491-497
Author(s):  
M. A. Galakhov ◽  
V. P. Kovalev
Keyword(s):  
Contact Region

Module-Based Static Structural Design of a Modular Reconfigurable Robot

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Richard Phillip Mohamed ◽  
Fengfeng (Jeff) Xi ◽  
Allan Daniel Finistauri
Keyword(s):  
Structural Design ◽  
Design Method ◽  
Optimal Solution ◽  
Local Deformation ◽  
Design Stage ◽  
Coordinate Frame ◽  
Reconfigurable Robots ◽  
Nonlinear Approach ◽  
Reconfigurable Robot

In this paper, the structural design of modular reconfigurable robots (MRRs) is studied. This problem is defined as the determination of proper module sizes according to the robot’s payload and end-effector deflection specifications. Because an MRR has multiple configurations, a simple design process is proposed in order to avoid performing the structural design stage at each configuration. The final structural design is only carried out at a single configuration that can guarantee the robot’s satisfactory performance for all remaining feasible configurations. It is shown that the module structural design stage can be performed at the local coordinate frame of each module. While the module local force requirement can be fully determined, the determination of the module local deformation requirement is redundant. Thus, there can exist multiple design solutions. To overcome this problem, a nonlinear approach using a genetic algorithm is used to search for an optimal solution. Finally, a design simulation is performed on an example MRR, and the results show the effectiveness of the proposed design method.

scholarly journals KALKULUS DIFERENSIAL DAN INTEGRAL OLEH FERMAT

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
Laila Hayati ◽  
Mamika Ujianita Romdhini
Keyword(s):  
Number Theory ◽  
Historical Development ◽  
Tangent Line ◽  
Ancient Times ◽  
Fermat’S Little Theorem

Abstrak. Dalam kuliah kalkulus modern, materi tentang pendifferensialan (turunan fungsi) dan konstruksi garis singgung terhadap suatu kurva diberikan terlebih dahulu daripada materi integral dan penentuan luas daerah di bawah suatu kurva. Hal ini berlawanan dengan urutan sejarah perkembangannnya. Penentuan luas daerah yang dibatasi oleh beberapa kurva telah ditemukan pada zaman kuno. Dalam tulisan ini membahas awal konstruksi garis singgung dan penentuan luas daerah yang dibatasi oleh suatu kurva yang pertama kali dibahas oleh Fermat. Kerja Fermat telah memberikan dasar bagi konsep kalkulus modern, khususnya pendifferensialan dan integral. Selain itu, Fermat dikenal sebagai orang yang memiliki kemampuan luar biasa dalam teori bilangan, antara lain dengan Fermat’s Little Theorem dan Fermat’s Last Theorem.Kata kunci: konstruksi garis singgung, luas daerah, differensial, dan integral, teori fermat. Abstrak. In modern calculus course, the material on derivative of the function and the construction of the tangent to the curve given first than the material on the integral and determining the area under a curve. This is contrary to the historical development. Determination of the area has been limited by several curves have been found in ancient times. In this paper discusses the start of construction of the tangent line and determining the area bounded by a curve that was first discussed by Fermat. Work Fermat has provided the basis for the concept of modern calculus, especially derivative and integral. In addition, Fermat is known as a person who has a remarkable ability in number theory, among others, by Fermat's Little Theorem and Fermat's Last Theorem.Keywords: construction of a tangent, wide areas, derivative and integral, Fermat Theory.

On the Analytical Determination of the Nominal Stresses in Dovetail Attachments

2020 ◽  
Author(s):  
Glenn Sinclair
Keyword(s):  
Finite Element ◽  
Closed Form ◽  
Contact Region ◽  
Essential Elements ◽  
Contact Stresses ◽  
Physical Models ◽  
Analytical Determination ◽  
Bending Stress ◽  
Attachment Model

Abstract Simple physical models are developed for the nominal contact stresses in dovetail attachments. These nominal stresses include the pressure, the shear traction, and the bending stress in the contact region, both during loading up and unloading. The models furnish closed-form expressions for these stresses. For a specific dovetail attachment, model values are compared with verified finite element values. As a result of the simplifications introduced to make the models tractable, model values only approximately equal finite element values. Nonetheless, the models capture the essential elements of the response of nominal stresses in dovetail attachments.

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