Impact Resistance and Energy Absorption of Functionally Graded Cellular Structures

2011 ◽  
Vol 69 ◽  
pp. 73-78 ◽  
Author(s):  
Xiao Kai Wang ◽  
Zhi Jun Zheng ◽  
Ji Lin Yu ◽  
Chang Feng Wang
Keyword(s):  
Energy Absorption ◽  
Impact Resistance ◽  
Functionally Graded ◽  
Cellular Structures ◽  
Stress Wave Propagation ◽  
Initial Kinetic Energy ◽  
Gradual Change ◽  
Two Dimensional ◽  
The One ◽  
The Impact

The dynamic response of functionally graded cellular structures subjected to impact of a finite mass was investigated in this paper. Compared to a cellular structure with a uniform cell size, the one with gradually changing cell sizes may improve many properties. Based on the two-dimensional random Voronoi technique, a two-dimensional topological configuration of cellular structures with a linear density-gradient in one direction was constructed by changing the cell sizes. The finite element method using ABAQUS/Explicit code was employed to investigate the energy absorption and the influence of gradient on stress wave propagation. Results show that functionally graded cellular structures studied are superior in energy absorption to the equivalent uniform cellular structures under low initial kinetic energy impacts, and the performance of such structures can be significantly improved when the density difference is enlarged. The stress levels at the impact and support ends may be reduced by introducing a gradual change of density in cellular structures when the initial impact velocity is low.

Interplay of fabric structure and shear thickening fluid impregnation in moderating the impact response of high-performance woven fabrics

2020 ◽  
Vol 54 (28) ◽  
pp. 4387-4395
Author(s):  
Sanchi Arora ◽  
Abhijit Majumdar ◽  
Bhupendra Singh Butola
Keyword(s):  
Beneficial Effect ◽  
Energy Absorption ◽  
Impact Energy ◽  
High Performance ◽  
Research Work ◽  
Impact Resistance ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Fabric Structure ◽  
The Impact

The beneficial effect of STF impregnation in enhancing the impact resistance of high-performance fabrics has been extensively reported in the literature. However, this research work reports that fabric structure has a decisive role in moderating the effectiveness of STF impregnation in terms of impact energy absorption. Plain woven fabrics having sett varying from 25 × 25 inch−1 to 55 × 55 inch−1 were impregnated with STF at two different padding pressures to obtain different add-ons. The impact energy absorption by STF impregnated loosely woven fabrics was found to be higher than that of their neat counterparts for both levels of add-on, while opposite trend was observed in case of tightly woven fabrics. Further, comparison of tightly woven plain, 2/2 twill, 3/1 twill and 2 × 2 matt fabrics revealed beneficial effect of STF impregnation, except for the plain woven fabric, establishing that there exists a fabric structure-STF impregnation interplay that tunes the impact resistance of woven fabrics.

scholarly journals Functionalization of silica particles to tune the impact resistance of shear thickening fluid treated aramid fabrics

RSC Advances ◽  
2017 ◽  
Vol 7 (78) ◽  
pp. 49787-49794 ◽  
Author(s):  
K. Talreja ◽  
I. Chauhan ◽  
A. Ghosh ◽  
A. Majumdar ◽  
B. S. Butola
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
Impact Resistance ◽  
Shear Thickening ◽  
Silica Particles ◽  
Modified Silica ◽  
Shear Thickening Fluid ◽  
Aramid Fabrics ◽  
And Control ◽  
The Impact

Kevlar fabrics treated with MTMS modified silica based STF showed better impact energy absorption as compared to APTES modified and control silica based STF treated fabrics, attributed to changes in interactions between fabrics and silica particles.

Quasi-Static Impact Response of Single-Curved Foldcore Sandwich Shells

2014 ◽  
Author(s):  
Joseph M. Gattas ◽  
Zhong You
Keyword(s):  
Energy Absorption ◽  
Mechanical Performance ◽  
Numerical Models ◽  
Preliminary Investigation ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Future Research ◽  
Initial Strength ◽  
Sandwich Shells ◽  
The Impact

Honeycomb core sandwich shells are used for many applications, but available unit architectures and global curvatures are limited. Numerous origami-core sandwich shells, known as foldcores, have been proposed as alternatives, but studies into their mechanical performance are few. This paper conducts a preliminary investigation into the impact resistance and energy absorption of single-curved foldcore sandwich shells that utilise Miura-derivative patterns as their core geometry. A numerical analysis on three Miura-derivative core patterns, the Arc-Miura (AM), Non-Developable Miura (ND), and Non-Flat Foldable Miura (NF) patterns, shows that ND and AM-type shells have similar impact resistance to each other, and superior impact resistance to NF-type shells. Prototypes of aluminium ND and AM-type foldcores are constructed and used to validate numerical models. Numerical models were then used to draw comparisons with an over-expanded honeycomb (OX-core) sandwich shell. It was seen that the OX-core had a better energy absorption capacity than either of the foldcores. However the AM-type foldcore possessed superior initial strength, and the ND-type possessed superior response uniformity, attributes that might be exploitable with future research. A brief parametric study on ND-type shells suggested that in general, for a given design radius and density, a foldcore shell configuration with a lower unit cell area-to-height ratio will have a higher energy absorption capability.

scholarly journals Impact Resistance of Polypropylene Fibre-Reinforced Alkali–Activated Copper Slag Concrete

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7735
Author(s):  
Vijayaprabha Chakrawarthi ◽  
Siva Avudaiappan ◽  
Mugahed Amran ◽  
Brindha Dharmar ◽  
Leon Raj Jesuarulraj ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Energy Absorption ◽  
Volume Fraction ◽  
Impact Resistance ◽  
Copper Slag ◽  
Polypropylene Fibre ◽  
Smelting Process ◽  
Fine Aggregate ◽  
Distribution Analysis ◽  
The Impact

Copper slag (CS) is produced during the smelting process to separate copper from copper ore. The object of the experimental research is to find the optimum percentage of CS and PPF volume fraction when CS replaces fine aggregate, and PPF volume fraction when subjected to impact loading. Copper slag was incorporated as 20%, 40%, 60%, 80% and 100% with PPF of 0.2–0.8% with 0.2% increment. The number of blows on failure of the specimen increases as the fibre volume increases. In addition, the energy absorption of composite concrete is higher than that of ordinary concrete. Concrete with up to 40% CS and 0.6% PPF volume shows a 111.72% increase in the number of blows for failure as compared to the control specimen. The impact resistance at failure was predicted by regression analysis, and very high regression coefficients of 0.93, 0.98 and 0.98 were obtained respectively at 7-, 14- and 28-days curing. In addition to regression analysis, a two-parameter Weibull distribution analysis was used to obtain reliable data on the number of blows at first cracking and eventual failure. The energy absorption at 28-day curing period is 1485.81 Nm which is 284% higher than the control mix. Based on the findings, it can be inferred that adding CS up to 60% densifies the microstructure due to its pozzolanic activity, while polypropylene fibre acts as a micro reinforcement, increasing the number of blows.

Containment and Arrest of Blade Shedding in Gas Turbine Engines Using Novel Dual-Ring Design

2021 ◽  
Author(s):  
Prayers Roy ◽  
Shaker A. Meguid
Keyword(s):  
Energy Absorption ◽  
Impact Damage ◽  
Impact Resistance ◽  
High Energy ◽  
Element Analysis ◽  
Single Ring ◽  
High Energy Absorption ◽  
Interfacial Gap ◽  
The Impact ◽  
Dual Ring

Abstract In this paper, we examine the energy absorption and containment capabilities of a newly proposed dual-ring design accounting for interactions between a released blade and fully bladed fan disk using 3D finite element analysis. The components of this dual-ring design are strategically selected to ensure high energy absorption and high impact resistance, thus leading to reduced damage of the disk and increased safety. Three containment ring designs are examined: (i) conventional single-ring design composed of one of titanium, aluminum or Kevlar, (ii) a newly proposed aluminium-Kevlar dual-ring arrangement, and (iii) dual-ring arrangement with an interfacial gap between them to arrest and contain the released blade and ensure free passage of the trailing blades. The results of our numerical simulations indicate that although the single-ring design resists penetration and contains the released blade within the confines of the disk, it does not remove the released blade from the path of the trailing blades leading to severe damage to the fan disk. On the contrary, our new dual-ring design, which contains an interfacial gap, has potential to successfully arrest the released blade within the confines of the ring and out of the path of the trailing blades. This design significantly can reduce the impact damage to the fan disk and reduces kinetic energy of the released blade to near zero in less than half a rotation of the fan disk.

Preparation of auxetic warp-knitted spacer fabric impregnated with shear thickening fluid for low-velocity impact resistance

2020 ◽  
pp. 152808372092701 ◽  
Author(s):  
Wanli Xu ◽  
Biao Yan ◽  
Dongmei Hu ◽  
Pibo Ma
Keyword(s):  
Shear Rate ◽  
Energy Absorption ◽  
Impact Resistance ◽  
Shear Thickening ◽  
Weight Fraction ◽  
Low Velocity Impact ◽  
Impact Behavior ◽  
Shear Thickening Fluid ◽  
Spacer Fabric ◽  
The Impact

This paper reports the preparation of auxetic warp-knitted spacer fabric impregnated with shear thickening fluid and studied its impact behavior under low-velocity impact loading. The shear thickening fluids have been prepared by mechanically dispersing 12 nm silica particles with weight fraction of 10, 15, 20, and 25% in various carriers (PEG200, PEG400, and PEG600). Rheological results indicate that shear thickening fluid experiences shear thickening transition at a specific shear rate. The critical shear rate reduces, and initial viscosity and maximum viscosity increase with the increase of silica weight fraction. The higher molecular weight of polyethylene glycols can lead to lower critical shear rate. The impact process of composite under impact loading can be divided into three stages. The warp-knitted spacer fabric with different negative Poisson’s ratio has a significant effect on the impact behavior. The warp-knitted spacer fabric with better auxetic performance endows composite better impact resistance, the specific performance is the deformation depth, and energy absorption and peak load increase with the increase of auxetic effect of fabric. The silica weight fraction of shear thickening fluid can increase the energy absorption of composite due to the shear thickening transition of shear thickening fluid. Shear thickening fluid has a synergistic effect with the auxetic warp-knitted spacer fabric on impact resistance of composite. The various carriers have no obvious influence on the overall energy absorption and impact load of composites.

Numerical Solution for Two-Dimensional Elastic Wave Propagation in Finite Bars

1967 ◽  
Vol 34 (3) ◽  
pp. 725-734 ◽  
Author(s):  
L. D. Bertholf
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Elastic Wave ◽  
Numerical Solutions ◽  
Step Change ◽  
Two Dimensional ◽  
One Dimensional ◽  
Elastic Bar ◽  
The One ◽  
The Impact

Numerical solutions of the exact equations for axisymmetric wave propagation are obtained with continuous and discontinuous loadings at the impact end of an elastic bar. The solution for a step change in stress agrees with experimental data near the end of the bar and exhibits a region that agrees with the one-dimensional strain approximation. The solution for an applied harmonic displacement closely approaches the Pochhammer-Chree solution at distances removed from the point of application. Reflections from free and rigid-lubricated ends are studied. The solutions after reflection are compared with the elementary one-dimensional stress approximation.

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