scholarly journals Postmortem Analysis Using Different Sensors and Technologies on Aramid Composites Samples after Ballistic Impact

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2853 ◽  
Author(s):  
Ignacio Rubio ◽  
Antonio Díaz-Álvarez ◽  
Richard Bernier ◽  
Alexis Rusinek ◽  
Jose Antonio Loya ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Numerical Models ◽  
Reaction Force ◽  
Residual Deformation ◽  
Ballistic Impact ◽  
Piezoelectric Sensors ◽  
Specimen Thickness ◽  
3D Scanner ◽  
Internal Damage ◽  
The Impact

This work focuses on the combination of two complementary non-destructive techniques to analyse the final deformation and internal damage induced in aramid composite plates subjected to ballistic impact. The first analysis device, a 3D scanner, allows digitalising the surface of the tested specimen. Comparing with the initial geometry, the permanent residual deformation (PBFD) can be obtained according to the impact characteristics. This is a significant parameter in armours and shielding design. The second inspection technique is based on computed tomography (CT). It allows analysing the internal state of the impacted sample, being able to detect possible delamination and fibre failure through the specimen thickness. The proposed methodology has been validated with two projectile geometries at different impact velocities, being the reaction force history on the specimen determined with piezoelectric sensors. Different loading states and induced damages were observed according to the projectile type and impact velocity. In order to validate the use of the 3D scanner, a correlation between impact velocity and damage induced in terms of permanent back face deformation has been realised for both projectiles studied. In addition, a comparison of the results obtained through this measurement method and those obtained in similar works, has been performed in the same range of impact energy. The results showed that CT is needed to analyse the internal damage of the aramid sample; however, this is a highly expensive and time-consuming method. The use of 3D scanner and piezoelectric sensors is perfectly complementary with CT and could be relevant to develop numerical models or design armours.

Influence of Several Parameters on Simulating the Ballistic Impact on a Homogenous Plate

2014 ◽  
Vol 658 ◽  
pp. 201-206
Author(s):  
Catalin Pirvu ◽  
Simona Badea ◽  
Lorena Deleanu
Keyword(s):  
Impact Velocity ◽  
Isotropic Material ◽  
Laboratory Tests ◽  
Plate Thickness ◽  
Ballistic Impact ◽  
Essential Parameter ◽  
Bullet Velocity ◽  
Von Mises ◽  
Von Mises Stresses ◽  
The Impact

This paper presents a simulation of a bullet impact on a plate made of a homogeneous and isotropic material. The developed model takes into account the yield and fracture limits of both involved materials for the bullet and the plate one. The model was developed with the help of Ansys 14.0 and could be used to establish a theoretical value of the plate thickness that will offer protection to the bullet penetration in order to minimize the number of laboratory tests for evaluating the plate resistance. The authors presented the influence of impact velocity of the bullet. The bullet velocity just reaching the plate is an essential parameter influencing the plate integrity. Also, the authors established a correlation between the evolution of the theoretical maximum von Mises stresses and the stages taking place during the impact.

scholarly journals Static and Dynamic Four-Point Flexural Tests of Concrete Beams with Variation in Concrete Quality, Reinforcement Properties and Impact Velocity

2021 ◽  
Vol 65 (2) ◽  
pp. 19-38
Author(s):  
Viktor Peterson ◽  
Anders Ansell
Keyword(s):  
Plastic Strain ◽  
Impact Velocity ◽  
Strain Distribution ◽  
Concrete Beams ◽  
Numerical Models ◽  
Reinforced Concrete Beams ◽  
Concrete Quality ◽  
Flexural Tests ◽  
Future Work ◽  
The Impact

Abstract This paper discusses the results from three experimental test series previously conducted. The tests consist of quasi-static monotonic and dynamic four-point flexural tests on reinforced concrete beams. The effect of varying material and load parameters on the plastic strain distribution and energy absorbed by the reinforcement is discussed. The main findings are the significant effect of the post-elastic region of the steel reinforcement and the impact velocity during dynamic loading. The results will be used to validate and construct numerical models in future work, where the findings presented can be investigated further.

Modelling the Fracture of High-Hardness Armour Steel in Taylor Rod-on-Anvil Experiments

2019 ◽  
Author(s):  
Brodie McDonald ◽  
Shannon Ryan ◽  
Stephen J. Cimpoeru ◽  
Nathan Edwards ◽  
Adrian Orifici
Keyword(s):  
Shear Band ◽  
Impact Velocity ◽  
Numerical Models ◽  
Computational Cost ◽  
Stress Triaxiality ◽  
High Hardness ◽  
Material Strength ◽  
Fracture Threshold ◽  
The Impact ◽  
Armour Steel

Abstract A series of Taylor rod-on-anvil experiments have been performed to validate the predicted impact velocity fracture threshold and fracture mode of a high hardness armour steel (HHA) obtained through explicit finite element simulations. Experimentally, the rods exhibited principal shear failure, a condition that can be closely linked to adiabatic shear band (ASB) formation in high strength steel. Using a stress triaxiality and Lode angle dependent failure strain criterion (Basaran 3D fracture locus), calibrated from quasi-static mechanical characterisation tests, the simulations were unable to predict the onset of fracture observed in experiments. As such, a strength-fading criterion is proposed using a phenomenological description to capture the loss of load-carrying capacity resulting from ASB formation. The ASB criterion is based on an exponential fit to experimentally-observed instability strains measured at different average stress triaxialities in a series of tests on inclined cylindrical and modified flat-hat specimens. With the prediction of ASB formation the material strength is reduced to model the thermal softening experienced in the shear band, and fracture of the material (in the form of element erosion) remains controlled by the Basaran fracture model. Incorporating the ASB-based criterion, the numerical models were found to accurately predict both the impact velocity fracture threshold, as well as the general appearance of the observed principal shear fracture. The proposed criterion enables the effects of ASB formation to be captured in an impact simulation with little increase in computational cost.

Modeling and simulation of impact behavior of 3D woven solid structure for ballistic application

2020 ◽  
pp. 152808372098046
Author(s):  
Lekhani Tripathi ◽  
Soumya Chowdhury ◽  
BK Behera
Keyword(s):  
Numerical Models ◽  
Woven Fabrics ◽  
Ballistic Impact ◽  
Woven Fabric ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact ◽  
Analytical Approaches

This study was carried out to understand and evaluate the response of 3 D woven fabrics upon the simulated ballistic forces. Under the low-velocity impact, analytical and numerical models were developed for determining the impact energy, which was used to evaluate the ballistic impact of projectile onto multiple-layered woven fabric panels based on the ballistic impact of single textile yarns. The behavior of primary and secondary yarns in a fabric under the ballistic impact was analyzed by both the models. The mechanisms of failure and energy dissipation of Kevlar fabric subjected to low-velocity impact were numerically investigated by using the ABAQUS platform as a tool of finite element method (FEM). The results obtained from numerical and analytical approaches were validated against experimental value which showed a good agreement.

Protection Effect on a Ballistic Impact of NATO 7.62 Ball Bullet into Helicopter Drive Shaft: Numerical Simulation

2011 ◽  
Vol 82 ◽  
pp. 710-715 ◽  
Author(s):  
Davide Lumassi ◽  
Andrea Manes ◽  
Marco Giglio
Keyword(s):  
Finite Element ◽  
Power Transmission ◽  
Numerical Models ◽  
Deformable Body ◽  
Numerical Procedure ◽  
Experimental Tests ◽  
Ballistic Impact ◽  
Drive Shaft ◽  
Constitutive Law ◽  
The Impact

Actual strategies and rules in peace keeping mission have led to an intensive use of helicopters exposing the aircraft and the crew to significant risks. Typical missions in fact involve low altitude flights in hostile environment where many threats can cause severe damages, leading eventually to the loss of the machine and the crew. According to this scenario, the tail rotor power transmission is one of the most critical components for its fundamental role to ensure flight stability and for its vulnerability, being very exposed during flight manoeuvre. In addition light weapons are wide spread, due to their cheapness and manoeuvrability. So the impact of 7.62x61 NATO ball 9.5 g bullet is an event anything but remote. This projectile is a full metal jacket bullet, with a brass jacket and a lead alloy core. Due to its mechanical characteristics, the soft lead core undergoes to high deformations and failures (mushroom and debris) during the impact, causing a large and extensive damaged area. Several researches have been developed to investigate the ballistic impact of conventional bullet against typical thin and lightweight aeronautical structure. As usual in this field, a complete methodology with experimental tests and numerical approaches has been carried on. In particular Finite Element analyses, although require complicate calibrations and validation which can be only made through indispensable experimental tests, represent a key resource. Very detailed numerical models are an extremely powerful tool to investigate the damage generated during an impact and allow simulating complex and extreme cases. With this premises direct impact between a 7.62x51 NATO ball 9.5 g bullet with a tube simulating an Helicopter drive shaft has been investigated by the authors in a previous work both with experimental and numerical activities with good agreement. However, considering the huge effect of bullet deformation verified during this activity, the modification of the bullet due to a preliminary impact with the surrounding frame (around the shaft in the real helicopter) could influence in a remarkable way the damage shape and extension in the shaft. This is an issue that is worth to further investigation and this is the aim of this paper. Basing only on a numerical procedure, previously assessed, an investigation of the impact of a NATO 7.62x51 mm ball 9.5 g bullet into an Al-6061-T6 pipe and its protection is presented. In particular the work will focus on the influence of the frame panel, which covers the transmission shaft, on the impact conditions. Analysis are carried out using the Finite Element commercial code ABAQUS/Explicit. Advanced materials’ descriptions, constitutive law and fracture criterion are introduced within the numerical model of the shaft and protection; projectile has been modelled as deformable body. Different impact conditions have also been tested in order to identify the worst impact condition.

Specimen Thickness and Impactor Mass Effects on Drop-Weight Impact Studies of GLARE 5 Fiber-Metal Laminates

2011 ◽  
Author(s):  
A. Seyed Yaghoubi ◽  
B. Liaw
Keyword(s):  
Impact Velocity ◽  
Volume Fraction ◽  
Energy Condition ◽  
Specimen Thickness ◽  
Fiber Metal Laminates ◽  
Drop Weight ◽  
Metal Volume ◽  
Fiber Metal ◽  
The Impact ◽  
Metal Volume Fraction

Impact responses and damage induced by a drop-weight instrument on GLARE 5 fiber-metal laminates (FMLs) with different thicknesses were studied. The effect of impactor mass was also considered. The damage characteristics were evaluated using both nondestructive ultrasonic and mechanical sectioning techniques. The ultrasonic C-scan technique could only assess the contour of entire damage area whereas more details of damage were obtained using the mechanical cross-sectioning technique. As expected, thicker GLARE 5 FMLs offered higher impact resistance. When subjected to the same impact energy, the entire damage contour enlarged as the specimen became thicker. Under the same impact condition, by reducing the impactor mass, the contact force escalated while the contact stiffness increased. Experimental results showed that the threshold cracking energy varied parabolically with respect to the impact velocity, metal volume fraction (MVF) and the specimen thickness. By increasing the metal volume fraction of the panels, the threshold cracking energy decreased parabolically. On the other hand, for the same MVF value, the cracking energy increased as the impactor mass increased. By increasing the panel thickness, the threshold cracking energy condition increased parabolically; whereas under the same impact velocity, the threshold cracking energy increased by increasing the impactor mass.

Experimental and Analytical Determination of the Coefficient of Dynamic Loading in the Contact Interaction of Bodies

2021 ◽  
Vol 1037 ◽  
pp. 649-654
Author(s):  
Dmitry N. Borodin ◽  
Dinamutdin N. Misirov ◽  
Sergey V. Semergey ◽  
Yuri P. Borzilov ◽  
Victor N. Yerovenko
Keyword(s):  
Dynamic Loading ◽  
Impact Velocity ◽  
Elastic Deformation ◽  
Contact Interaction ◽  
Residual Deformation ◽  
Contact Spot ◽  
The Body ◽  
Analytical Determination ◽  
Wheat Grains ◽  
The Impact

The calculation of the coefficient of dynamism of the contact interaction of bodies (lead balls and wheat grains with a moisture content of 11.5%) was carried out based on the hypothesis of equality of the work consumed during static and dynamic deformation of bodies, according to the formula:Θ=(So+Su)/(Sod+Su),where So – residual deformation of the body under static loading;Sod – residual deformation of the body under dynamic loading;Su – elastic deformation under static and dynamic loading.The components of the formula were determined on specially designed devices:– on an electromechanical press with static interaction of bodies, at a deformation rate of 0,055 m/s, the following values were determined from the load – discharge diagrams: the value of elastic deformation Su and the maximum residual deformation of bodies So.– on a vertical copra (at a contact interaction speed of 1-2 m/s) and a shock stand (at an impact speed of 11-15 m/s), the residual Sod deformation was determined by the size of the contact spot on the bodies after the impact.The calculated values of the dynamism coefficient were:for lead balls – 1,4-2,1;for wheat grains – 1,3-1,45.The results obtained indicate that the value of the dynamism coefficient increases with increasing impact velocity, with the same work spent on deformation, since the proportion of residual deformation in the total deformation of bodies decreases (bodies are strengthened).It is advisable to continue experiments to determine the coefficient of dynamism of bodies depending on the impact velocity, the configuration of the impact surface and the physical properties of the contacting bodies.

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

scholarly journals Simulation of Energy Absorption Performance of the Couplers in Urban Railway Vehicles during a Heavy Collision

Machines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 91
Author(s):  
Sunghyun Lim ◽  
Yong-hyeon Ji ◽  
Yeong-il Park
Keyword(s):  
Reaction Force ◽  
Crash Test ◽  
Railway Vehicle ◽  
Buffer System ◽  
Railway Vehicles ◽  
Hydraulic Shock Absorber ◽  
Coupling Buffer ◽  
Absorption Performance ◽  
Different Characteristics ◽  
The Impact

Railway vehicles are generally operated by connecting several vehicles in a row. Mechanisms connecting railway vehicles must also absorb front and rear shock loads that occur during a train’s operation. To minimize damage, rail car couplers are equipped with a buffer system that absorbs the impact of energy. It is difficult to perform a crash test and evaluate performance by applying a buffer to an actual railway vehicle. In this study, a simulation technique using a mathematical buffer model was introduced to overcome these difficulties. For this, a model of each element of the buffer was built based on the experimental data for each element of the coupling buffer system and a collision simulation program was developed. The buffering characteristics of a 10-car train colliding at 25 km/h were analyzed using a developed simulator. The results of the heavy collision simulation showed that the rubber buffer was directly connected to the hydraulic shock absorber in a solid contact state, and displacement of the hydraulic buffer hardly occurred despite the increase in reaction force due to the high impact speed. Since the impact force is concentrated on the vehicle to which the collision is applied, it may be appropriate to apply a deformation tube with different characteristics depending on the vehicle location.

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