Origami Crash Boxes Subjected to Dynamic Oblique Loading

2017 ◽  
Vol 84 (9) ◽  
Author(s):  
Caihua Zhou ◽  
Liangliang Jiang ◽  
Kuo Tian ◽  
Xiangjun Bi ◽  
Bo Wang
Keyword(s):  
Energy Absorption ◽  
High Performance ◽  
Slenderness Ratio ◽  
Absorption Capacity ◽  
Tube Length ◽  
Parameter Study ◽  
Original Design ◽  
Oblique Loading ◽  
The Comparative Study ◽  
Better Than

The energy absorption capacity of origami crash boxes (OCB) subjected to oblique loading is investigated in the present study. A conventional square tube (CST) with identical weight is employed as benchmark. The comparative study reveals that the origami crash box is more desirable than the conventional square tube in most of the range of load angle. A parameter study is performed to assess the effect of geometry parameters on the energy absorption characteristics. The geometry parameters are tube length L, tube width b, module length l, and width of folded lobe c. Considering that bamboo with large slenderness ratio could effectively resist wind load, a bulkhead-reinforced origami crash box is proposed as a high-performance energy absorption device. And an optimum structure designed based on the parameter study is investigated. The result suggests that the proposed tube performs much better than the original design.

Improving the Energy Absorption of Cruciform With Large Global Slenderness Ratio by Kirigami Approach and Welding Technology

2019 ◽  
Vol 86 (8) ◽  
Author(s):  
Caihua Zhou ◽  
Tong Li ◽  
Shizhao Ming ◽  
Zhibo Song ◽  
Bo Wang
Keyword(s):  
Energy Absorption ◽  
Progressive Collapse ◽  
Slenderness Ratio ◽  
Absorption Capacity ◽  
Buckling Mode ◽  
Euler Buckling ◽  
Thin Walled Structures ◽  
Welding Technology ◽  
Parametric Studies ◽  
Thin Walled

Conventional energy absorber usually employs stubby thin-walled structures. Compared with the limited number of stubby thin-walled structures, an equipment has a large number of slender thin-walled structures that has the potential to be used for energy absorption purpose as well. Therefore, improving the energy absorption capacity of these slender thin-walled structures can significantly benefit the crashworthiness of the equipment. However, these slender structures are inclined to deform in Euler buckling mode, which greatly limits their application for energy absorption. In this paper, kirigami approach combined with welding technology is adopted to avoid the Euler buckling mode of a slender cruciform. Both finite element simulations and experiments demonstrated that the proposed approach can trigger a desirable progressive collapse mode and thus improve the energy absorption by around 155.22%, compared with the conventional cruciform. Furthermore, parametric studies related to the kirigami pattern and global slenderness ratio (GSR) are conducted to investigate the improvement of this proposed approach on the energy absorption and the maximum critical value of GSR.

scholarly journals Behavior of Concrete-Filled Single and Double-Skin uPVC Tubular Columns Under Axial Compression Loads

2019 ◽  
Vol 13 (1) ◽  
pp. 164-177 ◽  
Author(s):  
Abraham M. Woldemariam ◽  
Walter O. Oyawa ◽  
Timothy Nyomboi
Keyword(s):  
Energy Absorption ◽  
Axial Compression ◽  
High Performance ◽  
Concrete Structures ◽  
Construction Materials ◽  
Absorption Capacity ◽  
Peak Strength ◽  
Energy Absorption Capacity ◽  
Tubular Columns ◽  
Double Skin

Background: There is an increased demand for high-performance materials in the construction industry due to the high cost, the difficulty of sourcing and shortcomings of the existing construction materials. Some of the deficiencies are corrosion of steel, brittle failure and rapid deterioration of reinforced concrete structures in a harsh environment. Nowadays, there is also a move from one material to another due to the difficulty of sourcing i.e. timber electric poles to concrete poles due to the difficulty of sourcing native hardwood. These situations have triggered the interest to develop an alternative structural system. Objective: This paper presents the behavior of unconfined concrete, Concrete-Filled Single Skin uPVC Tubular (CFSUT) and concrete-filled double skin uPVC tubular (CFDUT) members under axial compression loads. Method: The unconfined concrete cylinders, CFSUT and CFDUT specimens were prepared from a concrete class of C25 and tested using a UTM machine at a rate of 0.2MPa/s. The parameters considered where thickness to diameter ratio (2t/D), aspect ratio (h/D) and hollow ratio (d/D). Also, a model was developed to predict the peak strength of CFSUT and CFDUT specimens. Results: The result shows that both CFSUT and CFDUT specimens exhibited improved strength, ductility, and energy absorption capacity. For CFSUT and CFSUT specimens, the strength, ductility, and energy absorption capacity increased by more than 1.32, 3.75 and 14.75 times compared to the unconfined concrete specimens, respectively. It is found that the strength decreased as the h/D and d/D ratios increased. The result also shows that the strain of CFSUT and CFDUT at the peak strength increased by more than 3.16 times compared to the unconfined concrete specimens. The proposed model accurately predicted the peak strength with AAE of 2.13%. Conclusion: The uPVC confinement provided a remarkable improvement on the strength, ductility and energy absorption of concrete. Therefore, uPVC tubes can be used as confining material for bridge piers, piles, electric poles, and building columns to increase the strength, ductility and energy absorption of concrete structures.

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.

The Influence of Boundary Condition on the Impact Behavior of High Performance Fabrics

2018 ◽  
Vol 28 ◽  
pp. 47-54 ◽  
Author(s):  
Selim Gürgen
Keyword(s):  
Boundary Condition ◽  
Energy Absorption ◽  
Impact Velocity ◽  
High Performance ◽  
Absorption Capacity ◽  
Impact Behavior ◽  
Finite Element Software ◽  
Fabric Deformation ◽  
Absorption Performance ◽  
The Impact

Boundary condition is an important factor for the impact behavior of fabrics. In the present work, the effect of boundary condition on the impact behavior of fabrics was investigated modeling the impact conditions in a finite element software program. In the numerical simulations, fabric boundary condition and impact velocity were used as variable parameters and their effects were discussed in terms of fabric deformation and energy absorption capacity. Based on the study, the significance of boundary condition gradually diminishes as impact velocity increases. However, at low velocities, fabrics with free edges provide enhanced energy absorption performance in comparison to those with fixed edges. In addition, fabric deformation turns to local scale increasing impact velocity however, at low velocities, deformation is extended over a wider area on the fabrics.

Shock-Cushioning and Energy Absorption Performance Research of Aluminum Foam-Polyurethane Composite

2011 ◽  
Vol 287-290 ◽  
pp. 401-404
Author(s):  
Ming Si Qi ◽  
Wen Dong Zhang ◽  
Wei Yang ◽  
Hong Mei Wang ◽  
Bo Li
Keyword(s):  
Energy Absorption ◽  
Aluminum Foam ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
Polyurethane Composite ◽  
Foam Polyurethane ◽  
Curve Method ◽  
Absorption Performance ◽  
Performance Research ◽  
Better Than

The paper researched stress and strain of aluminum foam, polyurethane and aluminum foam-polyurethane composite via Ansys software, researched energy absorption capacity of the three material via energy absorption curve method, and researched energy absorption capacity of the aluminum foam-polyurethane composite under different shock and different thickness. The research results are obvious: under the same material parameter and 7800gn shock conditions the energy absorption of the aluminum foam-polyurethane composite is better than the monomer of the aluminum foam and the polyurethane. Under the same shock conditions, the thicker the composite is, the more energy it absorbs. Aluminum foam-polyurethane composite can plays cushioning and energy absorption roles when the acceleration speed reaches 7800gn

Energy-Controlled Design of Reinforced Ultra-High Performance Fiber Concrete Slabs against Airblast Loads

2008 ◽  
Vol 400-402 ◽  
pp. 107-112 ◽  
Author(s):  
Chengqing Wu ◽  
D.J. Oehlers ◽  
M. Rebentrost ◽  
J. Leach
Keyword(s):  
Energy Absorption ◽  
High Performance ◽  
Design Method ◽  
High Energy ◽  
Maximum Energy ◽  
Absorption Capacity ◽  
Reinforcement Ratio ◽  
Analysis Model ◽  
Energy Absorption Capacity ◽  
Optimal Reinforcement

Displacement-controlled design method is now being used by current guidelines such as TM5 and ASCE to design RC members against airblast load. If the maximum deflection of the designed member under airblast loads is less than the allowable deflection, the designed member is considered to be safe. Although the displacement-controlled design method is easy to use, it may not result in a design having maximum energy-absorption capacity against airblast loads, especially for a design of a reinforced ultra-high performance fibre concrete (RUHPFC) member which is of both high strength and high ductility, that is, high energy-absorption capacity. In this paper, a layered analysis model allowing for varying strain rates with time as well as along the depth of the member was used to calculate energy-absorption of a simple supported RUHPFC slab under airblast loads. An optimal reinforcement ratio of the slab was achieved by maximizing the energy absorption of the slab under different reinforcement ratios. The energy-controlled design method was validated by field blast tests. Using the validated design method, a designed slab with the optimal reinforcement ratio was also tested and the effectiveness of the design was demonstrated.

High Performance Fiber Composites with Enhanced Energy Absorption for Underground Construction

2012 ◽  
Vol 488-489 ◽  
pp. 617-621
Author(s):  
Massoumeh Farjadmand ◽  
Mohammad Safi
Keyword(s):  
Energy Absorption ◽  
High Performance ◽  
Fiber Type ◽  
Absorption Capacity ◽  
Fiber Content ◽  
Reinforced Composites ◽  
Energy Absorption Capacity ◽  
High Performance Fiber ◽  
Tunnel Lining Design ◽  
The Cost

In order to provide higher energy absorption capacity in fiber reinforced composites, it is normally required to use more volumes of fibers. This leads to economical limitations as the fiber content usually controls the cost of the composite mix. This research has tried to enhance the energy absorption capacity of the composite while keeping the fiber content constant or at the minimum possible value. A series of laboratory tests were conducted in Iran and Turkey with the same material and fiber type and some recommendations for achieving the optimized results were proposed. Beam and panel tests were used to account for the energy absorption and the results were used for tunnel lining design.

Advances in imaging SIMS studies of stained and BrdU-labelled human metaphase chromosomes

1995 ◽  
Vol 53 ◽  
pp. 932-933
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
R. Espinosa ◽  
M. M. Le Beau
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Analytical Sensitivity ◽  
Metaphase Chromosomes ◽  
Banding Patterns ◽  
Sector Mass Spectrometer ◽  
Staining Methods ◽  
The University ◽  
Secondary Ion ◽  
Better Than

We have shown previously that isotope-labelled nucleotides in human metaphase chromosomes can be detected and mapped by imaging secondary ion mass spectrometry (SIMS), using the University of Chicago high resolution scanning ion microprobe (UC SIM). These early studies, conducted with BrdU- and 14C-thymidine-labelled chromosomes via detection of the Br and 28CN- (14C14N-> labelcarrying signals, provided some evidence for the condensation of the label into banding patterns along the chromatids (SIMS bands) reminiscent of the well known Q- and G-bands obtained by conventional staining methods for optical microscopy. The potential of this technique has been greatly enhanced by the recent upgrade of the UC SIM, now coupled to a high performance magnetic sector mass spectrometer in lieu of the previous RF quadrupole mass filter. The high transmission of the new spectrometer improves the SIMS analytical sensitivity of the microprobe better than a hundredfold, overcoming most of the previous imaging limitations resulting from low count statistics.

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