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.

Low-Velocity Impact Response of Discontinuous Kirigami Cruciform Sandwich Panel

2019 ◽  
Vol 11 (05) ◽  
pp. 1950046 ◽  
Author(s):  
Caihua Zhou ◽  
Chaoxiang Xia ◽  
Shizhao Ming ◽  
Xiangjun Bi ◽  
Tong Li
Keyword(s):  
Energy Absorption ◽  
Manufacturing Process ◽  
Sandwich Panel ◽  
Mechanical Performance ◽  
Absorption Capacity ◽  
Low Velocity Impact ◽  
Bottom Surface ◽  
Low Velocity ◽  
Four Levels ◽  
The Impact

Cruciform structures have desirable energy absorption capacity. However, the engineering application is limited by the difficulties in the manufacturing process. In this paper, a kirigami approach is introduced to simplify the manufacturing process. Based on the kirigami strategy, a structure referred to as a discontinuous kirigami cruciform sandwich panel (DKC), is investigated to validate the mechanical performance in energy absorption. Experiments and numerical simulations were carried out to investigate the impact resistance of DKC under four levels of impact energy and the energy–absorption performance is evaluated by comparing to a typical energy–absorption device, pyramidal truss sandwich panel (PT). In order to reduce the initial impact force and the displacement of the bottom surface on the protected objective, the DKC is further optimized by introducing an additional cutout at the opposite end in each component plate. With the new design, the displacement of the bottom surface on the sandwich structure is reduced by 13.9%, together with a decrease of impact peak force and an increase of energy absorption.

High-Performance Impact-Resistant Concrete Mixture for Transportation Infrastructure Applications

2019 ◽  
Vol 2673 (12) ◽  
pp. 628-635 ◽  
Author(s):  
Kamal Baral ◽  
Jovan Tatar ◽  
Qian Zhang
Keyword(s):  
Energy Absorption ◽  
High Performance ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Flexural Behavior ◽  
Cementitious Composites ◽  
Repeated Impact ◽  
Energy Absorption Capacity ◽  
Transportation Infrastructures ◽  
The Impact

Engineered cementitious composites (ECC) is a class of high-performance fiber-reinforced cementitious composites featuring metal-like strain-hardening behavior under tension and high ductility. The highly ductile behavior of ECC often results in high impact resistance and energy absorption capacity, which make ECC suitable for applications in structures that are prone to impact damages, like exterior bridge girders, bridge piers, and crash barriers. In a recent study, a new ECC mixture has been developed using domestically available polyvinyl alcohol (PVA) fibers and regular river sand in replacement of imported PVA fibers and fine silica sand that are normally used in other ECC mixtures. The newly developed mixture, with improved local accessibility of raw materials, enables structural-scale applications of ECC in transportation infrastructures. To evaluate the suitability of the mixture for impact-resistant structures, in this paper, the tensile and flexural behavior of the newly developed material were characterized under pseudo-static loading and high strain-rate loadings up to 10−1 s−1. Direct drop-weight impact test was also conducted to assess the impact resistance and energy absorption capacity of the material. It was ensured that the ECC mixture maintains high tensile strain capacity above 1.8% under all tested strain rates. Regarding the damage characteristics, energy absorption capacity and load-bearing capacity during repeated impact loadings, ECC was found to have 75% higher energy dissipation capacity compared with regular reinforced concrete specimens and superior damage tolerance. The research results demonstrated that the newly developed ECC has a great potential to improve the impact resistance of transportation infrastructures.

Quasi-Static Impact Response of Alternative Origami-Core Sandwich Panels

2013 ◽  
Author(s):  
Joseph M. Gattas ◽  
Zhong You
Keyword(s):  
Failure Modes ◽  
Mechanical Performance ◽  
Sheet Material ◽  
Preliminary Investigation ◽  
Impact Resistance ◽  
Sandwich Panels ◽  
Experimental Models ◽  
Lateral Impact ◽  
Energy Absorbing ◽  
The Impact

Foldcore sandwich panels have been the focus of much recent study in the aerospace industry. Existing foldcores are composed of a partially folded Miura origami pattern sandwiched between two stiff facings, and have been shown to possess numerous useful properties for impact-resistant applications. Non-Miura origami pattern with similar geometric properties, specifically rigid-foldability and tessellation, may be used as potential alternative origami-cores for sandwich panels, however the mechanical performance of such cores remains an unexplored area. This paper conducts a preliminary investigation into the impact resistance of five non-Miura sandwich panels. The selected patterns are numerically analysed under quasi-static lateral impact loads, and comparisons are drawn with existing foldcore designs. Two particular patterns are found to have failure modes suited for energy-absorbing applications. Prototypes of these two cores are constructed from polypropylene sheet material and experimentally tested to validate numerical results. Reasonable correlation is seen in the force-displacement response of numerical and experimental models.

scholarly journals Experimental Studies on Punching Shear and Impact Resistance of Steel Fibre Reinforced Slag Based Geopolymer Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Srinivasan Karunanithi
Keyword(s):  
Energy Absorption ◽  
Steel Fibre ◽  
Impact Load ◽  
Impact Resistance ◽  
Experimental Studies ◽  
Absorption Capacity ◽  
Punching Shear ◽  
Geopolymer Concrete ◽  
Energy Absorption Capacity ◽  
Ultimate Failure

The study was focused on slag based geopolymer concrete with the addition of steel fibre. The slag based geopolymer concrete was under shear load and sudden impact load to determine its response. The punching shear represents the load dissipation of the material and the energy absorption capacity of the geopolymer concrete to impact load. The various percentage of steel fibre in the slag based geopolymer concrete was 0.5%, 1.0%, and 1.5%. Overall the dosage 0.5% of steel fibre reinforced slag based geopolymer shows better results with a punching shear of 224 kN and 1.0% of steel fibre incorporated geopolymer concrete had the better energy absorption capacity with 3774.40 N·m for first crack toughness and 4123.88 N·m for ultimate failure toughness.

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 Energy Absorption Capability of Thin-Walled Prismatic Aluminum Tubes with Spherical Indentations

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4304
Author(s):  
Miroslaw Ferdynus ◽  
Patryk Rozylo ◽  
Michal Rogala
Keyword(s):  
Aluminum Alloy ◽  
Energy Absorption ◽  
Numerical Models ◽  
Energy System ◽  
High Energy ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
Numerical Tests ◽  
Thin Walled ◽  
Crushing Behavior

The paper presents the results of numerical tests of impact and energy absorption capacity of thin-walled columns, subjected to axial impact loading, made of aluminum alloy, and having a square cross-section and spherical indentations on their lateral surfaces. The numerical models were validated using an experiment that was conducted on the Instron CEAST 9350 High Energy System drop hammer. Material properties of the applied aluminum alloy were determined on the basis of a static tension test. The crushing behavior of the columns and some crashworthiness indicators were investigated. On the basis of the results of the conducted analyses, conclusions were drawn about the most beneficial design/constructional variants in terms of achieved crashworthiness parameters.

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.

High and Low Speed Impact Characteristics of Nanocomposites

2015 ◽  
Vol 1105 ◽  
pp. 62-66 ◽  
Author(s):  
Saud Aldajah ◽  
Yousef Haik ◽  
Kamal Moustafa ◽  
Ammar Alomari
Keyword(s):  
High Speed ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Impact Testing ◽  
Energy Absorption Capacity ◽  
Low Speed ◽  
High Speed Impact ◽  
Bulletproof Vest ◽  
Impact Characteristics ◽  
The Impact

Nanocomposites attracted the attention of scientists due to their superior mechanical, thermal, chemical and electrical properties. This research studied the impact of adding carbon nanotubes (CNTs) to the woven Kevlar laminated composites on the high and low speed impact characteristics. Different percentages of CNTs were added to the woven Kevlar-Vinylester composite materials. An in-house developed drop weight testing apparatus was utilized for the low speed impact testing. Two different concentrations of the CNTs were added to a 15-layer woven Kevlar laminates, 0.32 wt% and 0.8 wt%. The results showed that: The 0.32 wt % CNT sample enhanced the interlaminar strength of the composite without enhancing the energy absorption capacity whereas, the 0.8 wt % CNT sample did not improve the impact resistance of the Kevlar composite.For the high speed impact tests, a bulletproof vest was prepared using woven Kevlar, resin, and CNTs at 1.5 w% percentage. The ballistic shooting was carried out by a professional shooter using a 30 caliber and 9 mm bullets for the tests. The CNT bulletproof sample bounced back the 30 caliber copper alloy bullet with no penetration.

Effects of Water-Borne Polyurethane on Calcium Silicate Hydrate and Toughness of Properties of Cementitious Composites

2012 ◽  
Vol 619 ◽  
pp. 545-552
Author(s):  
Bei Ding ◽  
Xia Zhang ◽  
Dong Liang Zhou ◽  
Chan Wen Miao
Keyword(s):  
Mechanical Performance ◽  
Concrete Strength ◽  
Harmful Effect ◽  
Impact Resistance ◽  
29Si Nmr ◽  
Size Change ◽  
Block Polymer ◽  
Chain Conformations ◽  
The Impact ◽  
Water Borne

A novel kind of block polymer with characteristics of rod-like chain conformations-water-borne polyurethane (PUA) was synthesized by incorporate polyacrylate (PA) into the PU chain to prepare an aqueous polyurethane-polyacrylate (PUA) hybrid emulsion with core-shell structure. The interactions between Water-borne PUA and C-S-H nanostructure, which include intercalation and the polymerization degree of C-S-H silicate chains, were studied by small angle X-ray diffraction spectra and 29Si NMR spectra, respectly. The influences of water-borne PUA on mechanical performance of C-S-H were investigated experimentally. The small XRD results show that no evidence is observed for any fundamental size change in the C-S-H particles that have been formed in the presence of polymer. The NMR results indicate that there is a significant increase in the Q2/Q1 ratio ranging from 0.5 for pure C-S-H to 2.2 for PUA-C-S-H, respectively. The degree of silicate polymerization increases from 3.0 for pure C-S-H to 6.4 for PUA-C-S-H by calculation. PUA had minimal harmful effect on the compressive strength whereas the flexural strength was increased by 23.2% with dosage of 0.5% and 23.3% with dosage of 1.0%, respectively.The fracture energy ratios of concrete with a dosage of PUA less than 1% are greatly improved more than double with the decreasing of concrete strength less than 10%. The water-borne PUA also enhances the impact resistance of concrete. The impact energy consumption of samples with PUA increase nearly three times more than reference samples, also better than samples with PP fiber.

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