scholarly journals Ballistic impact on concrete slabs: An experimental and numerical study

2021 ◽  
Vol 250 ◽  
pp. 02001
Author(s):  
Martin Kristoffersen ◽  
Oda Lunde Toreskås ◽  
Sumita Dey ◽  
Tore Børvik
Keyword(s):  
Numerical Study ◽  
Ballistic Impact ◽  
Image Correlation ◽  
Concrete Slabs ◽  
Cast Material ◽  
Impact Tests ◽  
Quality Material ◽  
The Impact ◽  
Steel Projectiles ◽  
Material Tests

The ballistic perforation resistance of 50 mm thick concrete slabs impacted by 20 mm diameter ogive-nose steel projectiles is investigated experimentally and numerically. Three commercially produced concretes with nominal unconfined compressive strengths of 35, 75 and 110 MPa were used to cast material test specimens and slabs. After curing, ballistic impact tests were carried out to determine the ballistic limit curve and velocity for each slab quality. Material tests instrumented with digital image correlation (DIC) were conducted along the ballistic impact tests. DIC measurements were used to establish engineering stress-strain curves for calibration of a modified version of the Holmquist-Johnson-Cook concrete model. Finite element simulations of the impact tests gave good conservative predictions.

Ballistic impact on fired clay masonry bricks

2019 ◽  
Vol 11 (3) ◽  
pp. 304-318 ◽  
Author(s):  
Christoph Sauer ◽  
Andreas Heine ◽  
Frank Bagusat ◽  
Werner Riedel
Keyword(s):  
Numerical Model ◽  
Numerical Study ◽  
Material Model ◽  
Ballistic Impact ◽  
Concrete Material ◽  
The Impact ◽  
Impact Experiments ◽  
Steel Projectiles ◽  
Experimental Effort ◽  
Spall Failure

We perform an experimental and numerical study of ballistic impact on the German fired clay brick material VMz28. Parameters for the concrete material model applied in hydrocode simulations stem from material characterization experiments, especially planar plate impact experiments, engineering assumptions, and parameter studies. The performance of the numerical model is illustrated by a comparison of its results to ballistic data on penetration and perforation of spherical steel projectiles. Agreement is found between experiment and simulation for residual velocities and penetration depths. The experimental damage patterns are reproduced in the simulation with sufficient agreement. The application of the model to the impact of another differently shaped generic projectile reveals good predictive capabilities in a part of the impact velocity range. For the deviation found in the other part, limitations of the model concerning the full reproduction of the observed spall failure are discussed as a possible explanation. Overall, with moderate experimental effort, a numerical model with reasonably good predictive capabilities is obtained for engineering purposes.

scholarly journals Optimization of soft armor: the response of single-ply para-aramid and ultra-high molecular weight polyethylene fabrics under ballistic impact

2020 ◽  
Vol 90 (15-16) ◽  
pp. 1713-1729 ◽  
Author(s):  
Calvin Ralph ◽  
Lisa Baker ◽  
Edward Archer ◽  
Alistair McIlhagger
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Wave Velocity ◽  
Hybrid System ◽  
Transverse Wave ◽  
Ballistic Impact ◽  
Image Correlation ◽  
Factor C ◽  
The Impact ◽  
Ultra High Molecular Weight

Typical soft armor systems are constructed of multiple layers of a single fabric type. This empirical research sought to begin optimization of these systems through hybridization, sequencing dissimilar armor fabrics to maximize their ballistic protective performance, by first investigating single plies with a spectrum of properties to determine their behavior and response to impact. Eight individual plain weave fabrics with varying yarns and thread counts were manufactured from para-aramid and ultra-high molecular weight polyethylene (UHMWPE) yarns and physical and ballistic characterizations were conducted. The ballistic impact tests established the specific energy absorption (SEA) of each fabric across a range of impact velocities (340–620 m·s–1) and the transverse displacement wave velocity across the rear of the fabric was found using digital image correlation. Low cover factor ( Cfab) fabrics (0.74–0.84) consistently showed faster transverse wave speed than the high Cfab fabrics (0.84–0.96) for any given yarn type. The relative SEA of the fabrics varied dependent on both the impact velocity and number of plies impacted. It was found that lower Cfab fabrics had the highest SEA, critical velocity and transverse wave velocity. UHMWPE fabrics were not considered suitable for a woven hybrid system as they had a significantly lower SEA compared to all the para-aramid fabrics. Results indicate that a hybrid system, when considered as a theoretical spaced system, would benefit from higher Cfab fabrics as rearward layers. However, transverse wave results suggest the lower response of these fabrics may inhibit lower Cfab fabrics at the front of a combined hybridized system.

An Experimental and Numerical Study of the Dynamic Fracture of Glass

2013 ◽  
Author(s):  
Liang Xue ◽  
Yuling Niu ◽  
Hohyung Lee ◽  
Da Yu ◽  
Satish Chaparala ◽  
...  
Keyword(s):  
Dynamic Fracture ◽  
Numerical Study ◽  
Damage Model ◽  
Experimental Studies ◽  
Image Correlation ◽  
Fea Model ◽  
Glass Fracture ◽  
Impact Area ◽  
The Impact ◽  
Dynamic Impact Loading

The needs of glass to resist the scratches, drops impact, and bump from everyday use lead to the importance of investigation of the glass fracture under dynamic impact loading. The strength of the glass under dynamic fracture conditions is significantly larger than that under quasi-static loading. There are several theoretic models. In this study, an accumulated damage model is implemented. The relation among the stress, loading rate, contact time and the fracture is investigated. The effect of impact area, impact energy and impact momentum on the glass fracture has been proved to further improve the dynamic fracture criterion of glass. For the experimental studies, the Digital Image Correlation (DIC) method enables one to obtain the first principal strain of the glass during the impact process. Moreover, the FEA model is developed in ANSYS/LS-DYNA™.

An Experimental and Numerical Study of the Behavior of the Thin Glass Edge Under Ball Drop Impact

2013 ◽  
Author(s):  
Liang Xue ◽  
Dapeng Liu ◽  
Hohyung Lee ◽  
Da Yu ◽  
Satish Chaparala ◽  
...  
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Image Correlation ◽  
Cover Glass ◽  
Thin Glass ◽  
Impact Process ◽  
Fea Model ◽  
Plane Displacement ◽  
The Impact ◽  
Glass Edge

Glass is widely used as cover glass to protect the smartphones, tablets, PCs, and TVs from everyday wear and tear nowadays. There has been an increasing effort to understand the global behavior of glass substrate under impact, but the behavior of the edge for the thin glass has rarely been touched. In this study, the dynamic response of the glass edge when impacted with 1.75-inch steel ball from different heights (different potential energy) and different angles is studied. High-speed camera is applied for the direct visualization of the whole impact process. The Digital Image Correlation (DIC) method enables to obtain displacements (in-plane displacement and out-of-plane displacement) of the glass during the impact process. The failure mode for the edge impact is found to be predominantly buckling. The tape used in this study decreases wave propagation from the impact location. In addition, the FEA model of edge impact test is developed in ANSYS/LS-DYNA™.

The Effect of a Coupling Agent on the Impact Behaviour of Flax Fibre Composites

2021 ◽  
pp. 1-17
Author(s):  
Cihan Kaboglu ◽  
Jun Liu ◽  
Haibao Liu ◽  
Pietro Russo ◽  
Giorgio Simeoli ◽  
...  
Keyword(s):  
Impact Loading ◽  
Coupling Agent ◽  
Testing Machine ◽  
Natural Fibers ◽  
Flax Fiber ◽  
Image Correlation ◽  
Impact Tests ◽  
Out Of Plane ◽  
Plane Displacement ◽  
The Impact

Abstract The effects of a coupling agent on the behavior of flax fiber reinforced composites have been investigated by testing the specimens under both quasi-static indentation and high velocity impact loading. The specimens are manufactured embedding a commercial flax fiber fabric in a polypropylene (PP) matrix, neat and pre-modified with a maleic anhydride grafted PP, the latter acting as a coupling agent to enhance the interfacial adhesion. Quasi-static (QS) compressive tests were performed using a dynamometer testing machine equipped with a high-density polyethylene indenter having the same geometry of the projectile employed in the impact tests. The impact tests were conducted setting three different impact velocities. Digital Image Correlation maps of out-of-plane displacement were employed to compare the specimens with and without the coupling agent. The QS testing results indicate that the coupling agent has an enhancing influence on the bending stiffness of tested flax composites. The testing results show that the coupling agent improves the mechanical behavior by decreasing the out-of-plane displacement under impact loading. This approach gives rise to new materials potentially useful for applications where impact performance is desired whilst also providing an opportunity for the incorporation of natural fibers to produce a lightweight composite.

Simple Analytical Models for Beams and Slabs Under Soft Impacts at Medium Speed

2008 ◽  
Author(s):  
J.-M. Rambach ◽  
F. Tarallo
Keyword(s):  
Reinforced Concrete ◽  
Analytical Models ◽  
Concrete Slabs ◽  
Predictive Tool ◽  
Simply Supported ◽  
Sdof System ◽  
Impact Tests ◽  
Reinforced Concrete Slabs ◽  
Non Linear ◽  
The Impact

A simply supported reinforced concrete slender beam is modeled by 3 rigid consecutive elementary beams, the median beam being connected to the others by 2 viscous and elastoplastic spiral springs. The model can be assimilated as a non linear SDOF system convenient for the motion study of beams within flexural deformation domain, with displacements up to the height of the beam. The characteristics of the visco-elastoplastic springs are tuned so as be consistent with the beam motion before and after impact: the rigidity of the elastic domain of the springs is consistent with natural vibration frequencies which may be reduced after the impact due to subsequent damages. The motion of the beam during and after the impact is analyzed with such model: the values of the main mechanical characteristics (rigidity, plastic limit, viscous damping) may then be obtained. The impact tests performed by VTT (Finland) on one-way concrete slabs consolidate this approach and give consistent experimental values for the elastoplastic laws to be introduced in the model. With this experimental validation, the model may be used as a predictive tool for resistance and for displacements, as far as reinforced concrete beams and slabs are concerned. A thin reinforced concrete slab, simply supported along its 4 edges, is modeled by 4 to 5 rigid trapezoidal elementary slabs connected together by visco-elastoplastic spiral springs along the hinges. A non linear SDOF system is then developed to capture the behavior of such a slab within a flexural deformation domain, with displacements up to the slab thickness. The mechanism involving large shear deformations under the impact (“punching cone”) is taken into account by adding a second degree of freedom. The existing tests on reinforced concrete slabs submitted to medium velocity impacts found in literature may be used to consolidate this approach and to specify the values to be introduced in the model. The model will be used to analyze the forthcoming results (in terms of resistance and displacements) of VTT impact tests on simply supported reinforced concrete slabs. The behavior of civil works structures submitted to impacting missiles can nowadays be analyzed either with sophisticated FE calculation codes, or with analytical models. These analytical models may constitute simple but useful engineer’s tools for sensitivity analyses and for results checking of the necessary more sophisticated computation codes, in terms of resistance and in terms of displacement. They may be simply implemented on any spreadsheet software.

scholarly journals Equi-Biaxial Loading Effect on Austenitic Stainless Steel Fatigue Life

2015 ◽  
Author(s):  
S. Bradaï ◽  
C. Gourdin ◽  
S. Courtin ◽  
J. C. Le Roux ◽  
C. Gardin
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Numerical Study ◽  
Strain Tensor ◽  
Austenitic Stainless Steels ◽  
Nuclear Industry ◽  
Image Correlation ◽  
Biaxial Fatigue ◽  
The Impact

Fatigue lifetime assessment is essential in the design of structures. Under-estimated predictions may result in unnecessary in service inspections. Conversely, over-estimated predictions may have serious consequences on the integrity of structures. In some nuclear power plant components, the fatigue loading may be equi-biaxial because of thermal fatigue. So the potential impact of multiaxial loading on the fatigue life of components is a major concern. Meanwhile, few experimental data are available on austenitic stainless steels. It is essential to improve the fatigue assessment methodologies to take into account the potential equi-biaxial fatigue damage. Hence this requires obtaining experimental data on the considered material with a strain tensor in equi-biaxial tension. Two calibration tests (with strain gauges and image correlation) were used to obtain the relationship between the imposed deflection and the radial strain on the FABIME2 specimen. A numerical study has confirmed this relationship. Biaxial fatigue tests are carried out on two austenitic stainless steels for different values of the maximum deflection, and with a load ratio equal to −1. The interpretation of the experimental results requires the use of an appropriate definition of strain equivalent. In nuclear industry, two kinds of definition are used: von Mises and TRESCA strain equivalent. These results have permitted to estimate the impact of the equibiaxiality on the fatigue life of components.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

scholarly journals Numerical Simulation of the Impact of the Heat Source Position on Melting of a Nano-Enhanced Phase Change Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1425
Author(s):  
Tarek Bouzennada ◽  
Farid Mechighel ◽  
Kaouther Ghachem ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Commercial Code ◽  
Tube Position ◽  
The Impact ◽  
Change Material

A 2D-symmetric numerical study of a new design of Nano-Enhanced Phase change material (NEPCM)-filled enclosure is presented in this paper. The enclosure is equipped with an inner tube allowing the circulation of the heat transfer fluid (HTF); n-Octadecane is chosen as phase change material (PCM). Comsol-Multiphysics commercial code was used to solve the governing equations. This study has been performed to examine the heat distribution and melting rate under the influence of the inner-tube position and the concentration of the nanoparticles dispersed in the PCM. The inner tube was located at three different vertical positions and the nanoparticle concentration was varied from 0 to 0.06. The results revealed that both heat transfer/melting rates are improved when the inner tube is located at the bottom region of the enclosure and by increasing the concentration of the nanoparticles. The addition of the nanoparticles enhances the heat transfer due to the considerable increase in conductivity. On the other hand, by placing the tube in the bottom area of the enclosure, the liquid PCM gets a wider space, allowing the intensification of the natural convection.

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