A Simple Analytical Model to Simulate Oblique Ballistic Impact onto Fabric

2011 ◽  
Vol 110-116 ◽  
pp. 3453-3458
Author(s):  
Mohamad Ali Akbari ◽  
Golam Hosein Liaghat ◽  
Hadi Sabouri
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Ballistic Impact ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Good Agreement

A simple analytical model for oblique ballistic impact of projectiles into fabrics are presented. This model is extension of Chocron-Benloulo penetration model. Results are compared with experimental data. There is good agreement between analytical and experimental results.

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

A Simple Analytical Model to Simulate Textile Fabric Ballistic Impact Behavior

1997 ◽  
Vol 67 (7) ◽  
pp. 520-528 ◽  
Author(s):  
Isaias Sidney Chocron-Benloulo ◽  
J. Rodríguez ◽  
Vicente Sánchez-Gálvez
Keyword(s):  
Composite Materials ◽  
Analytical Model ◽  
High Performance ◽  
Predictive Power ◽  
Ballistic Impact ◽  
Experimental Results ◽  
Impact Behavior ◽  
Light Weight ◽  
Simple Analytical Model ◽  
Textile Fabric

Composite materials have become very attractive as personal and vehicle armors because of their light weight and high performance. Unfortunately, these materials are difficult to simulate numerically or analytically, and the only way to check their performance is experimentally. A first step could be the study of the primary components of the composite. The fabric is undoubtedly the most important one, and an analytical model of its behavior is developed in this paper. The model calculates residual velocities, velocity and strain in the fabric histories, and absorbed energies. The comparison with experimental results for Kevlar 29 and the application of the model to Dyneema are very satisfactory as a demonstration of the good predictive power of an analytical model that is easy to understand and easy to compute.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

scholarly journals Response of a Warped Flexible Rotor with a Fluid Bearing

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Jim Meagher ◽  
Xi Wu ◽  
Chris Lencioni
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Equation Of Motion ◽  
Diagnostic Information ◽  
Flexible Rotor ◽  
Vibration Data ◽  
Rotor Model ◽  
Good Agreement

A two-complex-degrees-of-freedom model is developed and compared to experimental data for various amounts of rotor bow and its orientation to mass imbalance of the rotor. The equation of motion is developed by adding constant forces that rotate with the rotor to a Bently-Muszynska two-mode isotropic rotor model with a plane journal bearing. Diagnostic information discernable from probes at the bearing is explored and compared to midspan response, where previous research has concentrated. The model presented also extends earlier work by representing the effect of a nonrigid bearing. Good agreement between the analytical model and experiment demonstrates that the analysis presented can be useful to diagnose and balance residual shaft bow from probes located at the bearings, where vibration data are typically more available than midspan probes.

Viscous Dissipation in Laminar Water Flows in Micro-Tubes

2007 ◽  
Author(s):  
In-Hwan Yang ◽  
Mohamed S. El-Genk
Keyword(s):  
Experimental Data ◽  
Viscous Dissipation ◽  
Temperature Rise ◽  
Experimental Results ◽  
Numerical Calculations ◽  
Analytical Expression ◽  
Water Flows ◽  
Good Agreement

Numerical calculations are performed to investigate the effect of viscous dissipation on the temperature rise and friction numbers for laminar water flows in micro-tubes. The calculated values are compared with those determined from reported experimental data for glass and diffused silica micro-tubes (D = 16 – 101 μm and L/D = 625 – 1479). The results confirm a definite slip at the wall with slip lengths of ∼ 0.7 μm and 1.0 μm, which decrease the friction number and the temperature rise in the micro-tubes, but their effect gradually diminishes as either D or L/D increases. The friction number decreases exponentially as D decreases and, to a lesser extent, as L/D increases. The effect of L/D on the friction number is insignificant for micro-tube diameters ≤ 20 μm. For D > 400 μm, the friction number approaches that of Hagen-Posieuille of 64 for macro-tubes when L/D > 1500, but approaches higher values at smaller L/D. The dimensionless analytical expression developed for calculating the friction number and the temperature rise for water flows in micro-tubes is in good agreement with both the numerical and experimental results.

scholarly journals Validation of the Analytical Model of Oceanic Lidar Returns: Comparisons with Monte Carlo Simulations and Experimental Results

2019 ◽  
Vol 11 (16) ◽  
pp. 1870 ◽  
Author(s):  
Yudi Zhou ◽  
Weibiao Chen ◽  
Xiaoyu Cui ◽  
Aleksey Malinka ◽  
Qun Liu ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Analytical Model ◽  
Oblique Incidence ◽  
Relative Difference ◽  
Experimental Results ◽  
Coefficient Of Determination ◽  
Scattering Approximation ◽  
Angle Scattering ◽  
Mc Simulation ◽  
Good Agreement

The analytical model based on the quasi-single small-angle scattering approximation can efficiently simulate oceanic lidar signals with multiple scattering; thus, its accuracy is of particular interest to scientists. In this paper, the model is modified to include refraction at oblique incidence and is then compared with Monte Carlo (MC) simulations and experimental results. Under different conditions, the results calculated by the analytical model demonstrate good agreement with the MC simulation and experimental data. The coefficient of determination R2 considering the logarithm of signals and the root mean square of the relative difference δ are R2 = 0.998 and δ = 10% in comparison with the semi-analytic MC simulation and R2 = 0.952 and δ = 46% for the lidar experiment. Thus, the results demonstrate the validity of the analytical model in the simulation of oceanic lidar signals.

A simple projection moiré system to measure displacements of aircraft structures

2007 ◽  
Vol 42 (6) ◽  
pp. 477-495 ◽  
Author(s):  
U Galietti ◽  
K Genovese ◽  
L Lamberti ◽  
D Posa
Keyword(s):  
Analytical Model ◽  
Large Scale ◽  
Industrial Applications ◽  
Processing Method ◽  
Simple Analytical Model ◽  
Aerodynamic Loads ◽  
Out Of Plane ◽  
Plane Displacement ◽  
Good Agreement ◽  
Projection Moire

This work presents a simple projection moiré system (PMS) to measure displacements of large-scale aeronautical components. The system includes standard optics, uses a standard fringe-processing method, and relies on a simple analytical model to recover topographic information. An extensive calibration campaign, based on design of experiments, is conducted in order to find the best analytical model for retrieving the out-of-plane displacement field from the moiré pattern and to find the optimal combination of parameters involved in the measurement system. In order to check the suitability of the present PMS device for practical industrial applications, distortions induced by aerodynamic loads on a landing-light glazing of an Airbus A340 are measured. Experimental results are in good agreement with other measurements carried out independently.

Correlation Between Contact Start/Stop and Constant Speed Drag Testing in Magnetic Head-Disk Tribology

1993 ◽  
Vol 115 (3) ◽  
pp. 387-391 ◽  
Author(s):  
S. K. Ganapathi ◽  
F. E. Talke
Keyword(s):  
Experimental Data ◽  
Contact Force ◽  
Experimental Results ◽  
Constant Speed ◽  
Optical Profilometry ◽  
Magnetic Head ◽  
Good Agreement

A model to establish the correlation between wear in constant speed drag testing and contact start/stop testing is developed. The model is based on the Archard wear equation and uses the quasi-steady Kita-Kogure-Mitsuya model for the transition of a slider from sliding to flying to calculate the velocity dependent contact force between the slider and disk during start/stop. Experimental results for the wear of a zirconia overcoated disk are obtained for both start/stop and constant speed drag testing as a function of the number of repeated cycles using optical profilometry. The correlation between predictions and experimental data shows good agreement for up to at least 10,000 cycles of sliding.

Collision–induced absorption in gaseous methane at low temperatures

1986 ◽  
Vol 64 (7) ◽  
pp. 763-767 ◽  
Author(s):  
I. R. Dagg ◽  
A. Anderson ◽  
S. Yan ◽  
W. Smith ◽  
C. G. Joslin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Low Temperatures ◽  
Low Frequency ◽  
Frequency Region ◽  
Experimental Results ◽  
Published Data ◽  
Frequency Range ◽  
Simple Method ◽  
Induced Absorption ◽  
Good Agreement

A recently developed theory for collision-induced absorption in methane is compared with experimental results over a wider spectral range and at lower temperatures than previously reported. The present experimental results covering the frequency range below 400 cm−1 exhibit good agreement with other recently published data. The theory shows excellent agreement with experiment in the low-frequency region below approximately 200 cm−1 but underestimates the experimental data somewhat at higher frequencies. Possible theoretical reasons for this discrepancy are given. The theory represents a simple method of obtaining a good estimate of the collision-induced absorption spectra of methane in this frequency region and for extrapolating to lower temperatures for which experimentation is not feasible. In addition, the moments α1 and γ1are compared with earlier determinations and indicate good agreement with the previously obtained values for the octupole and hexadecapole moments of methane.

Liquid Container Filling and Charging

1976 ◽  
Vol 98 (2) ◽  
pp. 730-732
Author(s):  
R. H. Nunn ◽  
E. J. Gibson
Keyword(s):  
Closed Form ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Liquid Slug ◽  
Analytical Formulation ◽  
Closed Form Solutions

A simple analytical model has been developed to describe the dynamic behavior of a liquid slug as it is rapidly and suddenly rammed into a receiving chamber. Useful closed-form solutions are obtained from approximate versions of the governing relationships. Experimental results indicate the essential correctness of the analytical formulation.

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