scholarly journals Blast Alleviation of Sacrificial Cladding with Graded and Uniform Cellular Materials

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5616
Author(s):  
Yuanyuan Ding ◽  
Yuxuan Zheng ◽  
Zhijun Zheng ◽  
Yonggang Wang ◽  
Siyuan He ◽  
...  
Keyword(s):  
Blast Loading ◽  
Critical Length ◽  
Cellular Materials ◽  
Good Choice ◽  
Cellular Material ◽  
Optimal Length ◽  
Blast Design ◽  
Blast Response ◽  
Shock Models ◽  
Shock Fronts

Graded cellular material is a superb sandwich candidate for blast alleviation, but it has a disadvantage for the anti-blast design of sacrificial cladding, i.e., the supporting stress for the graded cellular material cannot maintain a constant level. Thus, a density graded-uniform cellular sacrificial cladding was developed, and its anti-blast response was investigated theoretically and numerically. One-dimensional nonlinear plastic shock models were proposed to analyze wave propagation in density graded-uniform cellular claddings under blast loading. There are two shock fronts in a positively graded-uniform cladding; while there are three shock fronts in a negatively graded-uniform cladding. Response features of density graded-uniform claddings were analyzed, and then a comparison with the cladding based on the uniform cellular material was carried out. Results showed that the cladding with uniform cellular materials is a good choice for the optimal mass design, while the density graded-uniform cladding is more advantageous from the perspective of the critical length design indicator. A partition diagram for the optimal length of sacrificial claddings under a defined blast loading was proposed for engineering design. Finally, cell-based finite element models were applied to verify the anti-blast response results of density graded-uniform claddings.

scholarly journals Four Questions in Cellular Material Design

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1060 ◽  
Author(s):  
Dhruv Bhate
Keyword(s):  
Paradigm Shift ◽  
State Of The Art ◽  
Material Design ◽  
Cellular Materials ◽  
Cellular Material ◽  
Optimal Parameters ◽  
Systematic Methodology ◽  
Design Software ◽  
Design Freedom ◽  
Key Questions

The design of cellular materials has recently undergone a paradigm shift, enabled by developments in Additive Manufacturing and design software. No longer do cellular materials have to be limited to traditional shapes such as honeycomb panels or stochastic foams. With this increase in design freedom comes a significant increase in optionality, which can be overwhelming to the designer. This paper aims to provide a framework for thinking about the four key questions in cellular material design: how to select a unit cell, how to vary cell size spatially, what the optimal parameters are, and finally, how best to integrate a cellular material within the structure at large. These questions are posed with the intent of stimulating further research that can address them individually, as well as integrate them in a systematic methodology for cellular material design. Different state-of-the-art solution approaches are also presented in order to provoke further investigation by the reader.

Micromechanical Modeling of Two-Dimensional Periodic Cellular Materials

2013 ◽  
Author(s):  
K. Alzebdeh ◽  
A. Al-Shabibi ◽  
T. Pervez
Keyword(s):  
Elastic Moduli ◽  
Cellular Materials ◽  
Unit Cell ◽  
Cellular Material ◽  
Micromechanical Modeling ◽  
Beam Model ◽  
Essential Boundary Condition ◽  
Representative Unit Cell ◽  
Structural Applications ◽  
Equivalent Continuum

The mechanical behavior of 2-D periodic cellular materials is investigated using a continuum-based modeling approach. Two micromechanical models are developed on the basis of representative unit cell concept in which skeleton of cellular material is modeled as elastic beams. The ANSYS finite element code is used to solve the beam model of skeleton. Elastic moduli of square and triangular networks comprising the microstructure of the cellular material are calculated based on an equivalent continuum model. This is achieved by equating the stored energy in skeleton of a unit cell to the strain energy of the equivalent continuum under a set of prescribed boundary conditions. A proper displacement-controlled (essential) boundary condition generates a uniform strain field in both models which corresponds to calculation of one elastic modulus at a time. Then, effective Young’s modulus and Poisson’s ratio of continuum are extracted from the calculated elastic moduli. The dependence of effective elastic constants on relative density and thickness to length ratio of the microstructure is investigated. Furthermore, the in-plane behavior of cellular solids in compression is explored with the help of current modeling. The proposed models may contribute to optimal designs of a new class of materials with tailored geometry and material properties which could be useful in a broad range of structural applications.

scholarly journals Analysis of the Response of a One-Storey One-Bay Steel Frame to Blast

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Rupert G. Williams ◽  
William A. Wilson ◽  
Reisa Dookeeram
Keyword(s):  
Analytical Study ◽  
Considerable Increase ◽  
Plastic Region ◽  
Blast Loading ◽  
Building Design ◽  
Charge Weight ◽  
Building Structures ◽  
Single Degree Of Freedom ◽  
Blast Design ◽  
Plane Frame

In recent years, there has been a considerable increase in perceived risks of blast loading attacks or similar incidents on structures. Blast design is therefore a necessary aspect of the design for building structures globally and as such building design must adapt accordingly. Presented herein is an attempt to determine the numerical response of a seismically designed single-degree-of-freedom (SDOF) structure to blast loading. The SDOF model in the form of a portal frame was designed to withstand a typical seismic occurrence in Northern Trinidad. Blast loads caused by applying a 500 kg charge weight of TNT at standoff distances of 45 m, 33 m, and 20 m were then applied to the model. The blast loading on the frame was determined using empirical methods. The analytical study showed that the seismically designed SDOF plane frame model entered the plastic region during the application of the blast load occurring up to the critical standoff distance.

scholarly journals Dynamic Response and Optimal Design of Curved Metallic Sandwich Panels under Blast Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Chang Qi ◽  
Shu Yang ◽  
Li-Jun Yang ◽  
Shou-Hong Han ◽  
Zhen-Hua Lu
Keyword(s):  
Dynamic Response ◽  
Energy Absorption ◽  
Sandwich Panel ◽  
Blast Resistance ◽  
Blast Loading ◽  
Outer Face ◽  
Air Blast ◽  
Blast Response ◽  
Artificial Neural Network Ann ◽  
Air Blast Loading

It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a “soft” outer face and a “hard” inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

Numerical Derivation of Pressure-Impulse Diagrams for Unreinforced Brick Masonry Walls

2011 ◽  
Vol 368-373 ◽  
pp. 1435-1439
Author(s):  
Xue Ying Wei ◽  
Tuo Huang ◽  
Nan Li
Keyword(s):  
Blast Loading ◽  
Material Model ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Strain Rate Effects ◽  
Pressure Impulse ◽  
Damage Level ◽  
Blast Response ◽  
Rate Effects ◽  
Brick And Mortar

Pressure-impulse diagrams have been extensively used for damage assessments of structural components subject to a specified blast loading. In this paper, a numerical method is used to generate pressure-impulse diagrams for unreinforced masonry walls subjected to blast loading. A previously developed plastic damage material model accounting for strain rate effects is used for brick and mortar. Three levels of damage criteria are defined based on maximum deflection of the wall and rotation of the supports. The obtained blast response for unreinforced masonry walls are validated against field test data. It is shown that the obtained pressure-impulse diagrams have an improved ability to evaluate the damage level of masonry walls.

Concurrent Topology Optimization of Lightweight Cellular Materials and Structures

2017 ◽  
Vol 868 ◽  
pp. 291-296
Author(s):  
He Ting Qiao ◽  
Shi Jie Wang ◽  
Xiao Ren Lv
Keyword(s):  
Topology Optimization ◽  
Material Design ◽  
Cellular Materials ◽  
Cellular Material ◽  
Design Stage ◽  
Concurrent Design ◽  
Design Variables ◽  
Macro Scale ◽  
Optimum Topology ◽  
Two Stages

In this paper, a two-stage optimization algorithm is proposed to simultaneously achieve the optimum structure and microstructure of lightweight cellular materials. Microstructure is assumed being uniform in macro-scale to meet manufacturing requirements. Furthermore, to reduce the computation cost, the design process is divided into two stages, which are concurrent design and material design. In the first stage, macro density and modulus matrix of cellular material are used both as design variables. Then, the optimum topology of macro-structure and modulus matrix of cellular materials will be obtained under this configuration. In the second stage, topology optimization technology is used to achieve a micro-structure of cellular material which is corresponded with the optimum modulus matrix in the earlier concurrent design stage. Moreover, the effectiveness of the present design methodology and optimization scheme is then demonstrated through numerical example.

The influence of interfacial bonding on the response of lightweight aluminium and glass fibre metal laminate panels subjected to air-blast loading

2017 ◽  
Vol 232 (8) ◽  
pp. 1402-1417 ◽  
Author(s):  
Genevieve S Langdon ◽  
CJ von Klemperer ◽  
GF Volschenk ◽  
T van Tonder ◽  
RA Govender
Keyword(s):  
Bond Strength ◽  
Epoxy Resin ◽  
Glass Fibre ◽  
Blast Loading ◽  
Adhesion Properties ◽  
Air Blast ◽  
Blast Response ◽  
Fibre Metal ◽  
Fibre Metal Laminate ◽  
Air Blast Loading

This paper examines the effects of glass fibre configuration and epoxy resin type on the response of glass fibre epoxy-based fibre metal laminate panels. These lightweight materials are excellent candidates for use in transportation applications, where mass is a major factor in design and materials selection. Interfacial bond strength was characterised through single leg bend testing and revealed varying failure characteristics for different epoxy configurations and surface treatments. A combination of bead blasting and silane treatment provided the best surface treatment for the aluminium, while SE84 epoxy resin gave superior adhesion properties compared to Prime 20ULV. Blast tests were performed to investigate the effect of bond strength on panel response under localised and more uniformly distributed air-blast loading conditions. Dimensionless analysis and failure mode identification were used to show that both fibre configuration and bond strength played a role in blast response but the bond strength (and particularly resin type) was more prominent.

Local Strain and Stress Calculation Methods of Irregular Honeycombs Under Dynamic Compression

2016 ◽  
Author(s):  
Jilin Yu ◽  
Peng Wang ◽  
Shenfei Liao ◽  
Zhijun Zheng
Keyword(s):  
Shock Wave ◽  
Wave Speed ◽  
Local Strain ◽  
Cellular Materials ◽  
Shock Model ◽  
Cross Sectional ◽  
One Dimensional ◽  
Loading Direction ◽  
Shock Models ◽  
The One

Several continuum-based shock models have been proposed to understand the dynamic compressive behavior of cellular materials, but they are mainly based on the quasi-static stress–strain relation and thus lack sufficient dynamic stress–strain information. A virtual ‘test’ of irregular honeycombs under constant-velocity compression is carried out using the finite element method. A method based on the optimization of local deformation gradient by using the least square method is employed to calculate the one-dimensional strain distribution in the loading direction of the specimen. Meanwhile, a method based on the cross-sectional engineering stress is developed to obtain the one-dimensional stress distribution in the loading direction. The two typical features of cellular materials under dynamic crushing, namely deformation localization and strength enhancement, can be characterized by the strain and stress distributions, respectively. The results also confirm the existence of plastic shock front propagation in cellular structures under high-velocity impact, from which the shock wave speed can be estimated. The shock wave speed obtained from the local strain field method coincides with that from the cross-sectional stress method. The results of shock wave speed are also compared with those predicted by continuum-based shock models. It is shown that the shock wave speed predicted by the R-PP-L (rate-independent, rigid–perfect plastic–locking) shock model or the R-LHP-L (rate-independent, rigid–linearly hardening plastic–locking) shock model is overestimated, but that predicted by the R-PH (rate-independent, rigid–plastic hardening) shock model is close to those obtained from the local strain and cross-sectional stress calculations using the cell-based finite element model.

Graphene-based cellular materials with extremely low density and high pressure sensitivity based on self-assembled graphene oxide liquid crystals

2018 ◽  
Vol 6 (32) ◽  
pp. 8717-8725 ◽  
Author(s):  
Xianzhang Wu ◽  
Kaiming Hou ◽  
Jingxia Huang ◽  
Jinqing Wang ◽  
Shengrong Yang
Keyword(s):  
High Pressure ◽  
Graphene Oxide ◽  
Liquid Crystals ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Cellular Materials ◽  
Cellular Material ◽  
Low Density ◽  
Pressure Sensitivity ◽  
Flexible Strain Sensor

A flexible strain sensor based on an ultralow density cellular material exhibits extremely high sensitivity.

scholarly journals Cluster-Based Optimization of Cellular Materials and Structures for Crashworthiness

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Kai Liu ◽  
Duane Detwiler ◽  
Andres Tovar
Keyword(s):  
Global Optimization ◽  
Structural Optimization ◽  
Conceptual Design ◽  
Nonlinear Models ◽  
Material Design ◽  
Cellular Materials ◽  
Cellular Material ◽  
Nonlinear Material ◽  
Optimization Approach ◽  
Material Models

The objective of this work is to establish a cluster-based optimization method for the optimal design of cellular materials and structures for crashworthiness, which involves the use of nonlinear, dynamic finite element models. The proposed method uses a cluster-based structural optimization approach consisting of four steps: conceptual design generation, clustering, metamodel-based global optimization, and cellular material design. The conceptual design is generated using structural optimization methods. K-means clustering is applied to the conceptual design to reduce the dimensional of the design space as well as define the internal architectures of the multimaterial structure. With reduced dimension space, global optimization aims to improve the crashworthiness of the structure can be performed efficiently. The cellular material design incorporates two homogenization methods, namely, energy-based homogenization for linear and nonlinear elastic material models and mean-field homogenization for (fully) nonlinear material models. The proposed methodology is demonstrated using three designs for crashworthiness that include linear, geometrically nonlinear, and nonlinear models.

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