Simulation on Shock Wave Propagation in Metallic Foams Subjected to Impact Loading

2012 ◽  
Vol 226-228 ◽  
pp. 536-540
Author(s):  
Yi Fen Zhang
Keyword(s):  
Wave Propagation ◽  
Impact Loading ◽  
Plastic Material ◽  
Progressive Collapse ◽  
Peak Stress ◽  
Metal Foams ◽  
Pulse Loading ◽  
Valuable Insight ◽  
Metallic Foams ◽  
Compressive Wave

A discretization elastic-plastic material model was used for simulating the shock waves transmission within metallic foams. The density heterogeneity of metallic foams was considered. Several types of aluminum foams are studied on the transmission of displacement and stresses wave under impact loading. The results reveal the characteristics of compressive wave propagation within the metal foams. Under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, and then reduces the crush of the objects. When the pulse is high sufficiently, on the fixed end of foam, stress enhancement may take place, where high peak stresses usually occur. The magnitude of the peak stress depends on the relative density of foams, the pulse loading intensity, the pulse loading duration as well as the density homogeneity of foam materials. This research offers valuable insight into the reliability of the metal foams used as vehicles and protective structure.

Speed of stress wave propagation in lung

1986 ◽  
Vol 61 (2) ◽  
pp. 701-705 ◽  
Author(s):  
R. T. Yen ◽  
Y. C. Fung ◽  
H. H. Ho ◽  
G. Butterman
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Impact Loading ◽  
Wave Speed ◽  
Dynamic Pressure ◽  
Transpulmonary Pressure ◽  
Lung Parenchyma ◽  
Surface Velocity ◽  
Stress Wave Propagation ◽  
Rabbit Lung

The speed of stress waves in the lung parenchyma was investigated to understand why, among all internal organs, the lung is the most easily injured when an animal is subjected to an impact loading. The speed of the sound is much less in the lung than that in other organs. To analyze the dynamic response of the lung to impact loading, it is necessary to know the speed of internal wave propagation. Excised lungs of the rabbit and the goat were impacted with water jet at dynamic pressure in the range of 7–35 kPa (1–5 psi) and surface velocity of 1–15 m/s. The stress wave was measured by pressure transducer. The distance between the point of impact and the sensor at another point on the far side of the lung and the transit time of the stress wave were measured. The wave speed in the goat lung was found to vary from 31.4 to 64.7 m/s when the transpulmonary pressure Pa-Ppl was varied from 0 to 20 cmH2O where Pa represents airway pressure and Ppl represents pleural pressure. In rabbit lung the wave speed varied from 16.5 to 36.9 m/s when Pa-Ppl was varied from 0 to 16 cmH2O. Using measured values of the bulk modulus, shear modulus, and density of the parenchyma, reasonable agreement between theoretical and experimental wave speeds were obtained.

In-Plane Dynamic Response Analysis of Hexagonal and Reentrant Honeycombs Under Uniaxial Impact Loading

2017 ◽  
Author(s):  
Zhen Li ◽  
Qiang Gao ◽  
Liangmo Wang ◽  
Jun Tang
Keyword(s):  
Dynamic Response ◽  
Impact Loading ◽  
Impact Resistance ◽  
Peak Stress ◽  
Nominal Stress ◽  
Response Analysis ◽  
Plateau Stress ◽  
Plateau Area ◽  
Stress Curve ◽  
The Impact

To investigate their in-plane dynamic response, a rigid plate with mass was given an initial velocity to impact (square) honeycombs in the X1 and X2 directions, respectively. Firstly, the impact model was built and validated. Then, impact resistance capacity research was conducted. Results showed that each honeycomb performed similarly in X1 and X2 directions, and the reentrant honeycomb usually used smaller displacement and time to absorb the same amount of kinetic energy. Thus, it is better for application if these factors were the main concerns. After that, the nominal stress at the proximal and distal ends were discussed under various impact velocities. It is shown that, under impact loading, the reentrant honeycomb generally showed higher initial peak stress as well as lower plateau stress at both proximal and distal ends. In addition, combining these with the deformation process of honeycombs, it was concluded that the formation of the plateau area of the nominal stress curve is related to the crushing displacement of the impact plate as well as the collapse of cells.

Plate bending wave propagation behavior under metal sphere impact loading

2018 ◽  
Vol 32 (3) ◽  
pp. 1117-1124 ◽  
Author(s):  
Seong-In Moon ◽  
To Kang ◽  
Jung-Seok Seo ◽  
Jeong-Han Lee ◽  
Soon-Woo Han ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Impact Loading ◽  
Plate Bending ◽  
Metal Sphere ◽  
Propagation Behavior ◽  
Bending Wave

Mesoscopic investigation of layered graded metallic foams under dynamic compaction

2018 ◽  
Vol 21 (14) ◽  
pp. 2081-2098 ◽  
Author(s):  
Jinhua Zhang ◽  
Yadong Zhang ◽  
Junyu Fan ◽  
Qin Fang ◽  
Yuan Long
Keyword(s):  
Impact Loading ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Metallic Foam ◽  
Layer By Layer ◽  
Metallic Foams ◽  
Mesoscopic Model ◽  
Layer Arrangement ◽  
Computed Tomography Images ◽  
Closed Cell

This article is aimed to reveal the dynamic response of layered graded metallic foam under impact loading using a three-dimensional mesoscopic model. First, a mesoscopic model for closed-cell metallic foam is proposed based on the X-ray computed tomography images. Second, a numerical analysis approach is presented and validated with test data. Third, it studies the dynamic behavior of the layered graded metallic foam under impact loading numerically. The metallic foam specimen is composed layer by layer. The porosity, which is a fraction of the voids volume over the total volume, is different with each other for the layers. Simulations are conducted to the specimen with increasing and decreasing porosity arrangement. Results show that the layer arrangement is critical to the dynamic properties. The mesoscopic deformation of cell walls and the energy absorption capability are also affected significantly. This article gives insights into the mechanical properties and mesoscopic deformation of layered graded metallic foam.

scholarly journals Role of Polymeric Coating on Metallic Foams to Control the Aeroacoustic Noise Reduction of Airfoils with Permeable Trailing Edges

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1087 ◽  
Author(s):  
Reza Hedayati ◽  
Alejandro Rubio Carpio ◽  
Salil Luesutthiviboon ◽  
Daniele Ragni ◽  
Francesco Avallone ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Metal Foams ◽  
Polymeric Coating ◽  
Metallic Foams ◽  
Noise Mitigation ◽  
Trailing Edge ◽  
Reference Case ◽  
Pore Sizes ◽  
Coated Metal ◽  
Trailing Edges

Studies on porous trailing edges, manufactured with open-cell Ni-Cr-Al foams with sub-millimeter pore sizes, have shown encouraging results for the mitigation of turbulent boundary-layer trailing-edge noise. However, the achieved noise mitigation is typically dependent upon the pore geometry, which is fixed after manufacturing. In this study, a step to control the aeroacoustics effect of such porous trailing edges is taken, by applying a polymeric coating onto the internal foam structure. Using this method, the internal topology of the foam is maintained, but its permeability is significantly affected. This study opens a new possibility of aeroacoustic control, since the polymeric coatings are temperature responsive, and their thickness can be controlled inside the foam. Porous metallic foams with pore sizes of 580, 800, and 1200 μm are (internally) spray-coated with an elastomeric coating. The uncoated and coated foams are characterized in terms of reduced porosity, average coating thickness and air-flow resistance. Subsequently, the coated and uncoated foams are employed to construct tapered inserts installed at the trailing edge of an NACA 0018 airfoil. The noise mitigation performances of the coated metal foams are compared to those of uncoated metal foams with either similar pore size or permeability value, and both are compared to the solid trailing edge reference case. Results show that that the permeability of the foam can be easily altered by the application of an internal coating on the metallic foams. The noise reduction characteristics of the coated foams are similar to equivalent ones with metallic materials, provided that the coating material is rigid enough not to plastically deform under flow conditions.

scholarly journals Ratcheting Assessment of a Fixed Tube Sheet Heat Exchanger Subject to In Phase Pressure and Temperature Cycles

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Khosrow Behseta ◽  
Donald Mackenzie ◽  
Robert Hamilton
Keyword(s):  
Heat Exchanger ◽  
Plastic Material ◽  
Sheet Thickness ◽  
Peak Stress ◽  
Material Model ◽  
Tube Sheet ◽  
Hardening Material ◽  
Perfectly Plastic ◽  
Inelastic Analysis ◽  
Plastic Shakedown

An investigation of the cyclic elastic-plastic response of an Olefin plant heat exchanger subject to cyclic thermal and pressure loading is presented. Design by analysis procedures for assessment of shakedown and ratcheting are considered, based on elastic and inelastic analysis methods. The heat exchanger tube sheet thickness is nonstandard as it is considerably less than that required by conventional design by formula rules. Ratcheting assessment performed using elastic stress analysis and stress linearization indicates that shakedown occurs under the specified loading when the nonlinear component of the through thickness stress is categorized as peak stress. In practice, the presence of the peak stress will cause local reverse plasticity or plastic shakedown in the component. In nonlinear analysis with an elastic–perfectly plastic material model the vessel exhibits incremental plastic strain accumulation for 10 full load cycles, with no indication that the configuration will adapt to steady state elastic or plastic action, i.e., elastic shakedown or plastic shakedown. However, the strain increments are small and would not lead to the development of a global plastic collapse or gross plastic deformation during the specified life of the vessel. Cyclic analysis based on a strain hardening material model indicates that the vessel will adapt to plastic shakedown after 6 load cycles. This indicates that the stress categorization and linearization assumptions made in the elastic analysis are valid for this configuration.

Effects of Geometrical Shapes and Orientations of Metal Foams Subjected to Impact Loading

2014 ◽  
Vol 564 ◽  
pp. 31-37 ◽  
Author(s):  
M. Ghazali Kamardan ◽  
Ahmad Mujahid Ahmad Zaidi ◽  
Z. Fitri Z. Abidin ◽  
M. Noh Dalimin ◽  
Othman Mohd Zaid
Keyword(s):  
Impact Loading ◽  
Metal Foam ◽  
Dynamic Deformation ◽  
Foam Cell ◽  
Deformation Behaviour ◽  
Metal Foams ◽  
Geometrical Shapes ◽  
Shape Effects ◽  
Parameter Values ◽  
Two Parameter

The effects of geometrical shapes are believed to play significant role in the deformation of metal foams under impact loading. This research was carried out to investigate the deformation behaviour of a single cellular cell of metal foam with different geometrical shapes. The simulation analyses were done on various two dimensional shapes with the consideration of the material properties. Two parameter values had been studied to determine the dynamic deformation behaviour of various geometrical shapes i.e. the internal energy and kinetic energy. It is found that, the geometrical shapes have shown significant effects on the dynamic deformation of single metal foam cell. It is hoped that this study could contribute significant result to the research of the metal foams especially in analyzing the shape effects to the behaviour of the metal foam under impact loading.

Modeling the progressive collapse behavior of metal foams

2007 ◽  
Vol 34 (3) ◽  
pp. 587-595 ◽  
Author(s):  
Sergey L. Lopatnikov ◽  
Bazle A. Gama ◽  
John W. Gillespie
Keyword(s):  
Progressive Collapse ◽  
Metal Foams ◽  
Collapse Behavior
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