Mass Loss and Nose Shape Change on Ogive-nose Steel Projectiles During Concrete Penetration

2012 ◽  
Vol 13 (3-4) ◽  
Author(s):  
Hai-Jun Wu ◽  
Feng-Lei Huang ◽  
Yi-Nan Wang ◽  
Zhou-Ping Duan ◽  
Yu Shan
Keyword(s):  
Experimental Data ◽  
Mass Loss ◽  
High Speed ◽  
Shape Change ◽  
Data Fitting ◽  
Nose Shape ◽  
Semi Empirical ◽  
The Impact ◽  
Steel Projectiles ◽  
Experimental Data Fitting

AbstractThe mass loss of the nose of projectile is an obvious phenomenon in high-speed penetration into concrete target. The mass loss percentage depends linearly on the impact velocities of projectile according to experimental data fitting results. A semi-empirical model, which can calculate the ogive-nose shape change due to mass loss, is developed in this paper. The modified penetration model shows that the penetration depth is influenced by nose erosion.

Evaluation of the Impact Formulae for Rigid Projectile Striking on Concrete Target

2011 ◽  
Vol 368-373 ◽  
pp. 894-900 ◽  
Author(s):  
Hao Wu ◽  
Qin Fang
Keyword(s):  
Penetration Depth ◽  
Empirical Formula ◽  
High Strength Concrete ◽  
High Speed ◽  
High Strength ◽  
Local Damage ◽  
High Speed Impact ◽  
Rigid Projectile ◽  
Semi Empirical ◽  
The Impact

Based on the large amounts of field impact tests with different projectile nosed shapes, the abilities of the existing classical empirical and semi-empirical impact formulae in predicting the local damage of normal and high strength concrete targets (NSCT & HSCT) under the strike of rigid projectile were evaluated. It finds that, firstly, for the penetration depth, the Forrestal and Chen & Li semi-empirical formulae, BRL and Whiffen empirical formulae are advised for the NSCT under the impact of ogive nosed projectile; and Chen & Li semi-empirical formula and ACE empirical formulae are advised for the NSCT under the impact of special nosed projectile; the dimensionless penetration depth of NSCT increases linearly with the non-dimensional impact factor. Secondly, for the penetration depth, Chen & Li semi-empirical formula is advised for the HSCT under the mid-to-high speed impact, and the existing formulae are not applicable while the speed of the projectile was relatively low. Thirdly, for the perforation mode of the target, the BRL and Chang empirical formulae are advised for the NSCT, and the Chen semi-empirical formula, ACE and BRL empirical formulae are advised for the HSCT.

scholarly journals Confronting theoretical predictions with experimental data; fitting strategy for multi-dimensional distributions

2015 ◽  
Vol 16 (1) ◽  
pp. 17 ◽  
Author(s):  
Przecinski Tomasz ◽  
Roig Pablo ◽  
Shekhovtsova Olga ◽  
Was Zbigniew ◽  
Zaremba Jakub
Keyword(s):  
Experimental Data ◽  
Data Fitting ◽  
Theoretical Predictions ◽  
Experimental Data Fitting

scholarly journals Experimental Study on the Mechanism of the Combined Action of Cavitation Erosion and Abrasion at High Speed Flow

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
X. Wang ◽  
Y. A. Hu ◽  
Z. H. Li
Keyword(s):  
Mass Loss ◽  
High Speed ◽  
Cavitation Erosion ◽  
Concrete Surface ◽  
High Speed Flow ◽  
Single Action ◽  
Speed Flow ◽  
Combined Action ◽  
Sand Particles ◽  
The Impact

AbstractA new experimental method on simulating the combined action of cavitation erosion and abrasion was proposed to investigate the erosion mechanism of overflow structure induced by the said processes. An automatic sand mixing device was invented for high-pressure and high-speed flow based on the characteristics of Venturi cavitation generator and hydraulic Bernoulli principle. The experimental system for the combined action of cavitation erosion and abrasion was designed and constructed, and high-speed sand mixing flow only appeared in the test section. A series of tests on the combined and single action of cavitation erosion and abrasion on hydraulic concrete and cement was carried out by using the invented experimental device. Results show that the wear of concrete surface exhibited the combined characteristics of cavitation erosion and abrasion under their joint action. The damage degree of concrete surface under the combined action was more severe than that under a single action. The mass loss of concrete under the combined action was higher than sum of mass losses of concrete under two single actions. The promotion and enhancement between cavitation erosion and abrasion existed in high-speed sand mixing flow. A power exponential relationship was observed between erosion mass loss and flow speed, and the velocity indexes approximated 4.5. Small and light sand particles easily follow water flow. Thus, the strong coupling effect of cavitation erosion and abrasion resulted from the presence of small sand particles. Given the different mechanisms of cavitation erosion and abrasion, presenting the skeleton structure formed by cavitation erosion was notably difficult under the action of abrasion. Meanwhile, abrasion wear easily occurred under the impact of cavitation erosion, and this result is due to the mechanism of the combined action of both processes.

Confidence-Based Uncertainty Quantification and Model Validation for Simulations of High-Speed Impact Problems

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Min-Yeong Moon ◽  
Oishik Sen ◽  
Nirmal Kumar Rai ◽  
Nicholas J. Gaul ◽  
Kyung K. Choi ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Computational Models ◽  
Classical Problem ◽  
Simulation Models ◽  
Confidence Levels ◽  
Model Confidence ◽  
Wide Range ◽  
Final Length ◽  
The Impact

Abstract Validation exercises for computational models of materials under impact must contend with sparse experimental data as well as with uncertainties due to microstructural stochasticity and variabilities in thermomechanical properties of the material. This paper develops statistical methods for determining confidence levels for verification and validation of computational models subject to aleatoric and epistemic uncertainties and sparse stochastic experimental datasets. To demonstrate the method, the classical problem of Taylor impact of a copper bar is simulated. Ensembles of simulations are performed to cover the range of variabilities in the material properties of copper, specifically the nominal yield strength A, the hardening constant B, and the hardening exponent n in a Johnson–Cook material model. To quantify uncertainties in the simulation models, we construct probability density functions (PDFs) of the ratios of the quantities of interest, viz., the final bar diameter Df to the original diameter D0 and the final length Lf to the original length L0. The uncertainties in the experimental data are quantified by constructing target output distributions for these QoIs (Df/D0 and Lf/L0) from the sparse experimental results reported in literature. The simulation output and the experimental output distributions are compared to compute two metrics, viz., the median of the model prediction error and the model confidence at user-specified error level. It is shown that the median is lower and the model confidence is higher for Lf/L0 compared to Df/D0, implying that the simulation models predict the final length of the bar more accurately than the diameter. The calculated confidence levels are shown to be consistent with expectations from the physics of the impact problem and the assumptions in the computational model. Thus, this paper develops and demonstrates physically meaningful metrics for validating simulation models using limited stochastic experimental datasets. The tools and techniques developed in this work can be used for validating a wide range of computational models operating under input uncertainties and sparse experimental datasets.

scholarly journals Amplitude, Latency, and Peak Velocity in Accommodation and Disaccommodation Dynamics

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Antonio J. Del Águila-Carrasco ◽  
José J. Esteve-Taboada ◽  
Eleni Papadatou ◽  
Teresa Ferrer-Blasco ◽  
Robert Montés-Micó
Keyword(s):  
Experimental Data ◽  
Exponential Function ◽  
Peak Velocity ◽  
Data Fitting ◽  
Mean Difference ◽  
Sigmoid Function ◽  
Analysis Strategies ◽  
Analysis Strategy ◽  
Experimental Data Fitting ◽  
Adequate Analysis

The aim of this work was to ascertain whether there are differences in amplitude, latency, and peak velocity of accommodation and disaccommodation responses when different analysis strategies are used to compute them, such as fitting different functions to the responses or for smoothing them prior to computing the parameters. Accommodation and disaccommodation responses from four subjects to pulse changes in demand were recorded by means of aberrometry. Three different strategies were followed to analyze such responses: fitting an exponential function to the experimental data; fitting a Boltzmann sigmoid function to the data; and smoothing the data. Amplitude, latency, and peak velocity of the responses were extracted. Significant differences were found between the peak velocity in accommodation computed by fitting an exponential function and smoothing the experimental data (mean difference 2.36 D/s). Regarding disaccommodation, significant differences were found between latency and peak velocity, calculated with the two same strategies (mean difference of 0.15 s and −3.56 D/s, resp.). The strategy used to analyze accommodation and disaccommodation responses seems to affect the parameters that describe accommodation and disaccommodation dynamics. These results highlight the importance of choosing the most adequate analysis strategy in each individual to obtain the parameters that characterize accommodation and disaccommodation dynamics.

scholarly journals The Impact of Convective Fluid Inertia Forces on Operation of Tilting-Pad Journal Bearings

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Thomas Hagemann ◽  
Christopher Zeh ◽  
Maximilian Prölß ◽  
Hubert Schwarze
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Local Pressure ◽  
Tilting Pad ◽  
Cfd Analyses ◽  
The Impact ◽  
Tilting Pad Journal Bearings ◽  
Inertia Forces

This paper presents a combination of experimental data, CFD analyses, and bearing code predictions on emergence of convective inertia fluid forces within the lube oil flow of tilting-pad journal bearings. Concordantly, experimental data and CFD analyses show a significant rise of local pressure at the transition between inlet and leading edge of tilting-pad, especially for high-speed applications with surface speeds up to 100 m/s. This effect can be related to convective inertia forces within fluid flow as cross-sections and flow character rapidly change at the pad entrance. An energy-based approach is implemented in the bearing code in order to provide enhanced boundary conditions for Reynolds equation considering this effect. As a result, predictions of bearing code achieved significant improved correlation with measured pressure distributions and CFD-data. Further, beside the local influence, a nonnegligible impact on characteristic parameters of bearing operation such as maximum temperature and stiffness and damping coefficients is observed. Finally, the results are critically analyzed and requirements to gain more distinct and reliable data are specified.

Modeling on mass loss and nose blunting of high-speed penetrator into concrete target

2018 ◽  
Vol 10 (1) ◽  
pp. 3-25
Author(s):  
Ouyang Hao ◽  
Xiaowei Chen
Keyword(s):  
Mass Loss ◽  
High Speed ◽  
Present Model ◽  
Volume Fraction ◽  
Depth Of Penetration ◽  
Calculation Results ◽  
Nose Shape ◽  
Good Agreement ◽  
Key Parameter ◽  
Concrete Target

Mass loss and nose blunting of the projectile are often observed in high-speed penetration into concrete target. A new theoretical model is established to present the process of mass abrasion of projectile during penetration and to predict the mass loss and nose shape of the residual projectile after penetration. In order to better describe the effect of aggregate on the mass abrasion of penetrator, both the aggregate volume fraction and its shear strength are introduced into the present model. In the present model, the caliber-radius-head value of projectile nose is a key parameter and the mass loss and nose shape of projectile can be obtained easily only by solving a differential equation for the caliber-radius-head value and the penetrating velocity v, which is much more convenient than the incremental calculation and all other methods of mass receding of projectile outer surface. The calculation results show a good agreement with experimental results. According to the present model of mass abrasion, the depth of penetration of projectile and its acceleration curve during penetration are further calculated by considering the effects of mass loss and nose blunting of projectile.

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