Preferentially Filled Foam Core Corrugated Steel Sandwich Structures for Improved Blast Performance

2015 ◽  
Vol 82 (6) ◽  
Author(s):  
Murat Yazici ◽  
Jefferson Wright ◽  
Damien Bertin ◽  
Arun Shukla
Keyword(s):  
Shock Tube ◽  
High Speed ◽  
Numerical Models ◽  
Front Face ◽  
High Speed Photography ◽  
Back Face ◽  
Foam Filling ◽  
Shock Impact ◽  
Foam Filled ◽  
Blast Performance

The mechanisms by which different morphologies of preferentially foam filled corrugated panels deform under planar blast loading, transmit shock, and absorb energy are investigated experimentally and numerically for the purpose of mitigating back-face deflection (BFD). Six foam filling configurations were fabricated and subjected to shock wave loading generated by a shock tube. Shock tube experimental results obtained from high-speed photography were used to validate the numerical models. The validated numerical model was further used to analyze 24 different core configurations. The experimental and numerical results show that soft/hard arrangements (front to back) are the most effective for blast resistivity as determined by the smallest BFDs. The number of foam filled layers in each specimen affected the amount of front-face deflections (FFDs), but did relatively little to alter BFDs, and results do not support alternating foam filling layers as a valid method to attenuate shock impact.

Numerical investigation on the dynamic response of foam-filled corrugated core sandwich panels subjected to air blast loading

2017 ◽  
Vol 21 (3) ◽  
pp. 838-864 ◽  
Author(s):  
Yuansheng Cheng ◽  
Tianyu Zhou ◽  
Hao Wang ◽  
Yong Li ◽  
Jun Liu ◽  
...  
Keyword(s):  
Total Energy ◽  
Energy Absorption ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Front Face ◽  
Back Side ◽  
Air Blast ◽  
Foam Filled ◽  
Blast Performance ◽  
Air Blast Loading

The ANSYS/Autodyn software was employed to investigate the dynamic responses of foam-filled corrugated core sandwich panels under air blast loading. The panels were assembled from metallic face sheets and corrugated webs, and PVC foam inserts with different filling strategies. To calibrate the proposed numerical model, the simulation results were compared with experimental data reported previously. The response of the panels was also compared with that of the empty (unfilled) sandwich panels. Numerical results show that the fluid–structure interaction effect was dominated by front face regardless of the foam fillers. Foam filling would reduce the level of deformation/failure of front face, but did not always decrease the one of back face. It is found that the blast performance in terms of the plastic deflections of the face sheets can be sorted as the following sequence: fully filled hybrid panel, front side filled hybrid panel, back side filled hybrid panel, and the empty sandwich panel. Investigation into energy absorption characteristic revealed that the front face and core web provided the most contribution on total energy absorption. A reverse order of panels was obtained when the maximization of total energy dissipation was used as the criteria of blast performance.

Use of a liquid shock tube as a device for the study of material deformation under impulsive loading conditions

2004 ◽  
Vol 218 (1) ◽  
pp. 39-51 ◽  
Author(s):  
B W Skews ◽  
O E Kosing ◽  
R J Hattingh
Keyword(s):  
Shock Tube ◽  
Deformation Process ◽  
High Speed ◽  
Pressure Pulse ◽  
Applied Pressure ◽  
Impulsive Loading ◽  
High Speed Photography ◽  
Material Deformation ◽  
Metal Plates ◽  
Versatile Tool

The deformation of metal plates and tubes achievable through the use of liquid shock waves generated in a shock tube is studied, with reference to both free-forming and forming the metal into dies, as well as to imprinting detailed features. The process is highly controllable, in terms of the magnitude and duration of the applied pressure pulse. A projectile is fired into a liquid column producing a high-pressure liquid shock wave which impinges on the testpiece. Different projectile materials, driving pressures and impact velocities are used to alter the energy and impulse transmitted. A particular attraction of its use in a laboratory is the application of high-speed photography to the deformation process. Illustration of the application of the facility to slamming studies and to fracture of brittle materials is included. It is concluded that the techniques employed offer a useful and versatile tool for many studies of material deformation.

Dynamics of Droplet Motion Induced by Electrowetting

2016 ◽  
Author(s):  
Yi Lu ◽  
Aritra Sur ◽  
Dong Liu ◽  
Carmen Pascente ◽  
Paul Ruchhoeft
Keyword(s):  
Contact Angle ◽  
High Speed ◽  
Numerical Models ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
High Speed Photography ◽  
Droplet Dynamics ◽  
Droplet Shape ◽  
Moving Contact Line ◽  
Moving Contact

Electrowetting has drawn significant interests due to the potential applications in electronic displays, lab-on-a-chip devices and electro-optical switches, etc. Current understanding of electrowetting-induced droplet dynamics is hindered by the inadequacy of available numerical and theoretical models in properly handling the dynamic contact angle at the moving contact line. A combined numerical and experimental approach was employed in this work to study the spatiotemporal responses of a droplet subject to EW with both direct current and alternating current actuating signals. The time evolution of the droplet shape was measured using high-speed photography. Computational fluid dynamics models were developed by using the Volume of Fluid-Continuous Surface Force method in conjunction with a selected dynamic contact angle model. It was found that the numerical models were able to accurately predict the key parameters of the electrowetting-induced droplet dynamics.

Modeling of Fabric Impact With High Speed Imaging and Nickel-Chromium Wires Validation

2011 ◽  
Vol 78 (5) ◽  
Author(s):  
Sidney Chocron ◽  
Trenton Kirchdoerfer ◽  
Nikki King ◽  
Christopher J. Freitas
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Numerical Models ◽  
Single Layer ◽  
Diagnostic Techniques ◽  
High Speed Photography ◽  
High Speed Imaging ◽  
Nickel Chromium ◽  
Validation Set ◽  
The Waves

Ballistic tests were performed on single-yarn, single-layer and ten-layer targets of Kevlar® KM2 (600 and 850 denier), Dyneema® SK-65 and PBO® (500 denier). The objective was to develop data for validation of numerical models so, multiple diagnostic techniques were used: (1) ultra-high speed photography, (2) high-speed video and (3) nickel-chromium wire technique. These techniques allowed thorough validation of the numerical models through five different paths. The first validation set was at the yarn level, where the transverse wave propagation obtained with analytical and numerical simulations was compared to that obtained in the experiments. The second validation path was at the single-layer level: the propagation of the pyramidal wave observed with the high speed camera was compared to the numerical simulations. The third validation consisted of comparing, for the targets with ten layers, the pyramid apex and diagonal positions from tests and simulations. The fourth validation, which is probably the most relevant, consisted of comparing the numerical and experimental ballistic limits. Finally for the fifth validation set, nickel-chromium wires were used to record electronically the waves propagating in the fabrics. It is shown that for the three materials the waves recorded during the tests match well the waves predicted by the numerical model.

scholarly journals Dynamic Response of Orthogonal Three-Dimensional Woven Carbon Composite Beams Under Soft Impact

2015 ◽  
Vol 82 (12) ◽  
Author(s):  
P. Turner ◽  
T. Liu ◽  
X. Zeng
Keyword(s):  
Finite Element ◽  
Composite Materials ◽  
Dynamic Response ◽  
Finite Element Modeling ◽  
High Speed ◽  
Three Dimensional ◽  
Composite Beams ◽  
High Speed Photography ◽  
Element Modeling ◽  
Back Face

This paper presents an experimental and numerical investigation into the dynamic response of three-dimensional (3D) orthogonal woven carbon composites undergoing soft impact. Composite beams of two different fiber architectures, varying only by the density of through-thickness reinforcement, were centrally impacted by metallic foam projectiles. Using high-speed photography, the center-point back-face deflection was measured as a function of projectile impulse. Qualitative comparisons are made with a similar unidirectional (UD) laminate material. No visible delamination occurred in orthogonal 3D woven samples, and beam failure was caused by tensile fiber fracture at the gripped ends. This contrasts with UD carbon-fiber laminates, which exhibit a combination of widespread delamination and tensile fracture. Post impact clamped–clamped beam bending tests were undertaken across the range of impact velocities tested to investigate any internal damage within the material. Increasing impact velocity caused a reduction of beam stiffness: this phenomenon was more pronounced in composites with a higher density of through-thickness reinforcement. A three-dimensional finite-element modeling strategy is presented and validated, showing excellent agreement with the experiment in terms of back-face deflection and damage mechanisms. The numerical analyses confirm negligible influence from through-thickness reinforcement in regard to back-face deflection, but show significant reductions in delamination damage propagation. Finite-element modeling was used to demonstrate the significant structural enhancements provided by the through-the-thickness (TTT) weave. The contributions to the field made by this research include the characterization of 3D woven composite materials under high-speed soft impact, and the demonstration of how established finite-element modeling methodologies can be applied to the simulation of orthogonal woven textile composite materials undergoing soft-impact loading.

Numerical Investigation Into the Effect of Stand-Off Distance on the Blast Performance of Metallic Corrugated-Core Sandwich Panels

2018 ◽  
Author(s):  
Sipei Cai ◽  
Jun Liu ◽  
Yuansheng Cheng ◽  
Weiwei Hao ◽  
Pan Zhang
Keyword(s):  
Dynamic Response ◽  
Total Energy ◽  
Energy Absorption ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Face Sheet ◽  
Front Face ◽  
Absorption Characteristic ◽  
Structural Dynamic ◽  
Blast Performance

The ANSYS/AUTODYN software was employed to investigate the dynamic response of the metallic sandwich panels subjected to air blast loading. The sandwich panels were composed of two face sheets and a trapezoidal corrugated-core. To validate the numerical models, the simulation results were compared with experimental data reported previously. In the simulation works, the process of shock wave propagation and the structural dynamic response were analyzed. Meanwhile, the influences of the stand-off distance between the explosive charge and the front face sheet on the fluid-structure interaction effect, dynamic response and the energy absorption of sandwich panels were investigated. Numerical results demonstrated that the impulse intensity decreased dramatically with the increase of stand-off distance. The slapping between the front face sheet and the back face sheet could be observed at the stand-off distances of 50 mm and 100 mm, while the sandwich panel exhibited the “strong core” response mode under the stand-off distance of 150 mm. Investigations into energy absorption characteristic revealed that the total energy absorption reduced with the increase of stand-off distance. The front face and corrugated-core provided the most contribution on total energy absorption. Moreover, the energy absorption proportion of corrugated-core had a positive correlation with the stand-off distance.

Shock response of filled corrugated sandwich structures under extreme temperatures

2016 ◽  
Vol 20 (1) ◽  
pp. 130-149 ◽  
Author(s):  
Payam Fahr ◽  
Murat Yazici ◽  
Arun Shukla
Keyword(s):  
Digital Image Correlation ◽  
Shock Tube ◽  
High Temperatures ◽  
Digital Image ◽  
High Speed ◽  
Syntactic Foam ◽  
Shock Pressure ◽  
Image Correlation ◽  
Back Face ◽  
Out Of Plane

Shock tube experiments were performed to investigate the blast response of corrugated steel cellular core sandwich panels filled with a silicone based syntactic foam at room and high temperatures. The syntactic foam filler was prepared by mixing a two-part silicone mixture with glass microspheres; its microstructure, and mechanical properties were also characterized. The syntactic foam-filled sandwich panels were loaded via air shock pressure by using the shock tube with a fixture capable of testing materials at temperatures up to 900℃. High-speed photo-optical methods, digital image correlation techniques, were used in tandem with optical band-pass filters and high intensity light sources for providing sufficient contrast at elevated temperatures. Back-face deformation images were captured using two synchronized high-speed cameras while a third camera captured the side view deformation images. The shock pressure profiles and digital image correlation analysis were used to obtain the impulse imparted to the specimen, transient deflection, in-plane strain and out-of-plane velocity of the back-face sheet. It was observed that using the syntactic foam as a filler material decreased the front face and back face deflections by 42% and 27%, respectively, as compared to the empty sandwich panel. At high temperatures, the silicone-based syntactic foam decomposes into silica, a stable and non-hazardous byproduct. The highest impulse was imparted to the specimen at room temperature and subsequently lower impulses with increasing temperatures were observed. Due to the increased ductility of steel at high temperatures, the specimens demonstrated an increase in back face deflection, in-plane strain and out-of-plane velocity with increased temperatures, with weld failure being the primary form of core damage.

Crack divergence phenomena in tempered glass

2020 ◽  
Vol 13 (3) ◽  
pp. 115-129
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Glass Plate ◽  
Acute Angle ◽  
Divergence Angle ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Thick Glass

High speed photography using the Cranz-Schardin camera was performed to study the crack divergence and divergence angle in thermally tempered glass. A tempered 3.5 mm thick glass plate was used as a specimen. It was shown that two types of bifurcation and branching existed as the crack divergence. The divergence angle was smaller than the value calculated from the principle of optimal design and showed an acute angle.

Experimental study of hydrodynamic effects in the inverse water hydrocarbon emulsions flow in microchannels

2016 ◽  
Vol 11 (1) ◽  
pp. 30-37 ◽  
Author(s):  
A.A. Rakhimov ◽  
A.T. Akhmetov
Keyword(s):  
High Speed ◽  
Petroleum Industry ◽  
Chemical Compounds ◽  
High Viscosity ◽  
Blocking Effect ◽  
High Speed Photography ◽  
Simple Chemical ◽  
Reported Study ◽  
Dynamic Blocking ◽  
Hydrodynamic Effects

The paper presents results of hydrodynamic and rheological studies of the inverse water hydrocarbon emulsions. The success of the application of invert emulsions in the petroleum industry due, along with the high viscosity of the emulsion, greatly exceeding the viscosity of the carrier phase, the dynamic blocking effect, which consists in the fact that the rate of flow of emulsions in capillary structures and cracks falls with time to 3-4 orders, despite the permanent pressure drop. The reported study shows an increase in viscosity with increasing concentration or dispersion of emulsion. The increase in dispersion of w/o emulsion leads to an acceleration of the onset of dynamic blocking. The use of microfluidic devices, is made by soft photolithography, along with high-speed photography (10,000 frames/s), allowed us to see in the blocking condition the deformation of the microdroplets of water in inverse emulsion prepared from simple chemical compounds.

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