An Experimental Investigation of Beam Stresses Produced by Oblique Impact of a Steel Sphere

1956 ◽  
Vol 23 (4) ◽  
pp. 606-611
Author(s):  
D. M. Cunningham ◽  
Werner Goldsmith
Keyword(s):  
Experimental Investigation ◽  
Normal Incidence ◽  
Oblique Impact ◽  
Angle Of Incidence ◽  
Bending Stress ◽  
Beam Size ◽  
Beam Length ◽  
Oblique Collision ◽  
Steel Sphere ◽  
Simply Supported

Abstract An experimental investigation designed to study the phenomenaincident to the oblique collision of 1/2-in-diam steel spheres with mild-steel and annealed drill-rod beams at oblique angles of incidence has been undertaken. Initial ball velocities ranged from 30 ft/sec to 150 ft/sec, beam sizes varied from 1/4 in. × 1/4 in. to 3/4 in. × 3/4 in., angles of incidence were chosen from 85 deg to normal incidence, and simply supported, clamped, and free beams were employed. Information is reported concerning the values of maximum bending stress at various positions along the beam as function of the angle of incidence and as a function of beam size for various angles of incidence. The progressive dispersion of the initial transient has been examined in detail. The effect of end supports, effective beam length, and repetitive shots into the same hole upon stress are described.

Kinematic Phenomena Observed During the Oblique Impact of a Sphere on a Beam

1956 ◽  
Vol 23 (4) ◽  
pp. 612-616
Author(s):  
Werner Goldsmith ◽  
D. M. Cunningham
Keyword(s):  
Initial Velocity ◽  
Oblique Impact ◽  
Beam Deflection ◽  
Steel Beams ◽  
Angle Of Incidence ◽  
Beam Size ◽  
Contact Duration ◽  
Steel Sphere ◽  
Velocity Of Propagation ◽  
Kinetics Of

Abstract Experimental data relating to the kinetics of oblique impact of 1/2-in-diam steel sphere upon steel beams at initial velocities ranging from 30 to 150 fps are presented. The variation of beam deflection, contact duration, trajectory of the sphere, and contour topography with angle of incidence, beam size, and initial velocity have been determined, and the velocity of propagation of several waves has been ascertained.

Effect of Pre-Tension on Ballistic Resistance of Woven Fabric

2014 ◽  
Vol 566 ◽  
pp. 325-331 ◽  
Author(s):  
V.P.W. Shim ◽  
Y.B. Guo ◽  
X.Y. Tan
Keyword(s):  
High Speed ◽  
Normal Incidence ◽  
Woven Fabric ◽  
Angle Of Incidence ◽  
Ballistic Limit ◽  
Normal Impact ◽  
Steel Sphere ◽  
Deformation And Failure ◽  
Ballistic Resistance ◽  
Gas Gun

An experimental investigation into projectile penetration of pre-tensioned woven fabric samples – Tawron® CT 717 (plain weave) – is undertaken. Specimens are clamped at their top and bottom edges, and pre-stretched by forces of 200N, 1000N, 2000N, 3000N and 4000N respectively. They are then oriented at various angles (0, 7.5°, 15° and 30°) from the vertical (perpendicular to the horizontal axis of a gas gun), and subjected to impact by a 12mm diameter steel sphere. A high-speed camera is utilized to observe the deformation and failure of the fabric, and to determine the residual projectile velocity. For normal incidence, the ballistic limit initially increases, then decreases with pre-tension, displaying a maximum resistance for a pre-tension of about 2000N. With respect to the angle of incidence (obliquity of impact), for target inclinations of 7.5° and 15°, pre-tension has minimal influence on the ballistic limit, while for an inclination of 30°, the effect of pre-tension on the ballistic limit is similar to that for normal impact.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

scholarly journals An Electrostatic Self-Excited Resonator with Pre-Tension/Pre-Compression Constraint for Active Rotation Control

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 650
Author(s):  
Ruide Yun ◽  
Yangsheng Zhu ◽  
Zhiwei Liu ◽  
Jianmei Huang ◽  
Xiaojun Yan ◽  
...  
Keyword(s):  
Maximum Velocity ◽  
Flapping Wings ◽  
Variable Velocity ◽  
Beam Length ◽  
Dc Voltage ◽  
Middle Position ◽  
Simply Supported ◽  
Maximum Value ◽  
Constraint Structure

We report a novel electrostatic self-excited resonator driven by DC voltage that achieves variable velocity-position characteristics via applying the pre-tension/pre-compression constraint. The resonator consists of a simply supported micro-beam, two plate electrodes, and two adjustable constraint bases, and it can be under pre-compression or pre-tension constraint by adjusting the distance L between two constraint bases (when beam length l > L, the resonator is under pre-compression and when l < L, it is under pre-tension). The oscillating velocity of the beam reaches the maximum value in the position around electrodes under the pre-compression constraint and reaches the maximum value in the middle position between two electrodes under the pre-tension condition. By changing the constraint of the microbeam, the position of the maximum velocity output of the oscillating beam can be controlled. The electrostatic self-excited resonator with a simple constraint structure under DC voltage has great potential in the field of propulsion of micro-robots, such as active rotation control of flapping wings.

scholarly journals Abrasive jet micro-machining of metals

2021 ◽  
Author(s):  
Sayeed Ally
Keyword(s):  
Normal Incidence ◽  
Impact Angle ◽  
Oblique Impact ◽  
Micro Machining ◽  
Surface Evolution ◽  
Abrasive Particles ◽  
Micro Features ◽  
Semi Empirical ◽  
First Time ◽  
Good Agreement

Abrasive jet micro-machining is a process that utilizes small abrasive particles entrained in a gas stream to erode material, creating micro-features such as channels and holes. Erosion experiments were carried out on aluminum 6061-T6, Ti-6A1-4V alloy, and 316L stainless steel using 50 μm A1₂O₃ abrasive powder launched at an average speed of 106 m/s. The dependence of erosion rate on impact angle was measured and fitted to a semi-empirical model. The erosion data was used in an analytical model to predict the surface evolution of unmasked channels machined with the abrasive jet at normal and oblique incidence, and masked channels at normal incidence. The predictions of the model were in good agreement with the measured profiles for unmasked channels at normal and oblique impact, and masked channels in at normal incidence up to an aspect ratio (channel depth/width) of 1.25. For the first time, it has been demonstrated that the surface evolution of features machined in metals can be predicted.

scholarly journals Flexural Interpretation of Simply Supported Laminated Composite Beam

2020 ◽  
Vol 8 (5) ◽  
pp. 3559-3565
Keyword(s):  
Shear Deformation ◽  
Composite Beam ◽  
Laminated Composite ◽  
Beam Theory ◽  
Composite Beams ◽  
Shear Stresses ◽  
Bending Stress ◽  
Simply Supported ◽  
Laminated Composite Beam ◽  
Laminated Composite Beams

In this Paper, the analysis of simply supported laminated composite beam having uniformly distributed load is performed. The solutions obtained in the form of the displacements and stresses for different layered cross ply laminated composite simply supported beams subjected uniformly distributed to load. Different aspect ratio consider for different results in terms of displacement, bending stress and shear stresses. The shear stresses are calculated with the help of equilibrium equation and constitutive relationship. Using displacement field including trigonometric function of laminated composite beams are derived from virtual displacement principle. There are axial displacement, transverse displacement, bending stress and shear stresses. In addition, Euler-Bernoulli (ETB), First order shear deformation beam theory (FSDT), Higher order shear deformation beam theory (HSDT) and Hyperbolic shear deformation beam theory (HYSDT) solution have been made for comparison and better accuracy of solutions and results of static analyses of laminated composite beams for simply supported laminated composite beam.

Response of a Simply Supported Timoshenko Beam to a Purely Random Gaussian Process

1958 ◽  
Vol 25 (4) ◽  
pp. 496-500
Author(s):  
J. C. Samuels ◽  
A. C. Eringen
Keyword(s):  
Timoshenko Beam ◽  
Beam Theory ◽  
Beam Equation ◽  
Mean Square ◽  
Bending Stress ◽  
Random Loading ◽  
Simply Supported ◽  
The Mean ◽  
Timoshenko Beam Equation ◽  
Classical Beam Theory

Abstract The generalized Fourier analysis is applied to the damped Timoshenko beam equation to calculate the mean-square values of displacements and bending stress, resulting from purely random loading. Compared with the calculations, based on the classical beam theory, it was found that the displacement correlations of both theories were in excellent agreement. Moreover, the mean square of the bending stress, contrary to the results of the classical beam theory, was found to be convergent. Computations carried out with a digital computer are plotted for both theories.

Experiments on the Buckling of Simply-Supported Rectangular Plates

1969 ◽  
Vol 73 (703) ◽  
pp. 607-608 ◽  
Author(s):  
A. C. Mills
Keyword(s):  
Experimental Investigation ◽  
Theoretical Analysis ◽  
Boundary Conditions ◽  
Buckling Load ◽  
Theoretical Solution ◽  
Rectangular Plates ◽  
Uniform Load ◽  
Simply Supported

In ref. (1) Pope presents a theoretical analysis of the buckling of rectangular plates tapered in thickness under uniform load in the direction of taper. An experimental investigation into the end load buckling problem for a plate having simply-supported edges with the sides prevented from moving normally in the plane of the plate is described in ref. (2). For these boundary conditions the theoretical solution is exact. However, the compatability equation is not satisfied exactly when the sides are free to move in the plane of the plate. This experimental investigation demonstrates that the buckling load is nevertheless adequately predicted by the analysis in these circumstances.

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