Curved Crease Tube Structures as an Energy Absorbing Crash Box

2016 ◽  
Author(s):  
Daniel Garrett ◽  
Zhong You ◽  
Joseph M. Gattas
Keyword(s):  
Numerical Analysis ◽  
Failure Mode ◽  
Maximum Increase ◽  
Good Correspondence ◽  
Average Force ◽  
Failure Characteristics ◽  
Maximum Reduction ◽  
Energy Absorbing ◽  
Minimal Benefit ◽  
Better Than

Straight-crease origami crash boxes have previously been designed to possess a near optimum failure mode for a tubular energy-absorbing device. This failure mode, termed a ‘complete diamond mode’ (CDM), possesses a low peak force Pmax and high average force Pavg, caused by generation of travelling hinge lines that propagate laterally during crushing. The present study investigates the hypothesis that a curved crease structure could further improve failure characteristics by having a lower Pmax due to the initially curved corner lobes. An experimental and numerical investigation was conducted using aluminium curved crease origami tubes, with certain curved crease tubes exhibiting the desired CDM and good correspondence seen between experimental and numerical behaviours. A parametric numerical analysis on 45 steel curved crease origami tubes showed a maximum reduction in Pmax of 67% was observed, which is better than the straight-crease origami crash boxes in this respect. A maximum increase in Pavg of 65% was observed, which is worse than straight-crease origami crash boxes. A lower Pmax was thus achieved as hypothesised, however this improvement came at the expense of a reduction in average force. Curved crease crash boxes are therefore concluded to have minimal benefit over existing straight crease crash box designs.

Compression and consolidation characteristics of structured natural clay

2004 ◽  
Vol 41 (6) ◽  
pp. 1250-1258 ◽  
Author(s):  
J -C Chai ◽  
N Miura ◽  
H -H Zhu ◽  
Yudhbir
Keyword(s):  
Numerical Analysis ◽  
Void Ratio ◽  
Natural Clay ◽  
Hardening Law ◽  
Modified Cam Clay ◽  
Calculated Load ◽  
Natural Clays ◽  
Consolidation Behavior ◽  
Better Than ◽  
Cam Clay

The compression and consolidation behavior of some structured natural clays are discussed. It is shown that for some structured natural clays, the relation between void ratio (e) and mean effective stress (p′) is more linear in a ln(e + ec) – ln(p′) plot (where ec is a soil parameter) than in an e – ln(p′) plot. It is proposed that for structured natural clay with a sensitivity value greater than 4, a linear ln(e + ec) – ln(p′) relation can be used in settlement and consolidation calculation. The effect of introducing a linear ln(e + ec) – ln(p′) relation on the calculated load–settlement curve and consolidation behavior of structured clays is discussed. The linear ln(e + ec) – ln(p′) relation was incorporated into the modified Cam–clay model by modifying the hardening law of the model. It is shown that using the linear ln(e + ec) – ln(p′) relation simulated the consolidation behavior of the structured natural clays better than using the linear e – ln(p′) relation.Key words: structured natural clay, compression, consolidation, constitutive model, numerical analysis.

scholarly journals Numerical Simulation on In-plane Deformation Characteristics of Lightweight Aluminum Honeycomb under Direct and Indirect Explosion

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2222 ◽  
Author(s):  
Xiangcheng Li ◽  
Yuliang Lin ◽  
Fangyun Lu
Keyword(s):  
Plane Deformation ◽  
Buffering Capacity ◽  
Response Mode ◽  
Deformation Characteristics ◽  
Rigid Plate ◽  
Dynamic Impact ◽  
Aluminum Honeycomb ◽  
Energy Absorbing ◽  
Deformation Modes ◽  
Better Than

Lightweight aluminum honeycomb is a buffering and energy-absorbed structure against dynamic impact and explosion. Direct and indirect explosions with different equivalent explosive masses are applied to investigate the in-plane deformation characteristics and energy-absorbing distribution of aluminum honeycombs. Two finite element models of honeycombs, i.e., rigid plate-honeycomb-rigid plate (RP-H-RP) and honeycomb-rigid plate (H-RP) are created. The models indicate that there are three deformation modes in the X1 direction for the RP-H-RP, which are the overall response mode at low equivalent explosive masses, transitional response mode at medium equivalent explosive masses, and local response mode at large equivalent explosive masses, respectively. Meanwhile, the honeycombs exhibit two deformation modes in the X2 direction, i.e., the expansion mode at low equivalent explosive masses and local inner concave mode at large equivalent explosive masses, respectively. Interestingly, a counter-intuitive phenomenon is observed on the loaded boundary of the H-RP. Besides, the energy distribution and buffering capacity of different parts on the honeycomb models are discussed. In a unit cell, most of the energy is absorbed by the edges with an edge thickness of 0.04 mm while little energy is absorbed by the other bilateral edges. For the buffering capacity, the honeycomb in the X1 direction behaves better than that in the X2 direction.

Numerical/Experimental Research on Welded Joints in Aluminium Truss Girders

2016 ◽  
Vol 710 ◽  
pp. 295-300
Author(s):  
Dianne van Hove ◽  
Frans Soetens
Keyword(s):  
Numerical Analysis ◽  
Failure Mode ◽  
Experimental Research ◽  
Welded Joints ◽  
Failure Load ◽  
Full Scale ◽  
Numerical Calculations ◽  
Failure Behavior ◽  
Design Rules ◽  
Steel Design

Welded joints in a 30 meter span aluminium truss girder were investigated numerically and experimentally. Since aluminium design rules for welded K-and N-joints in CHS truss girders were lacking the joints were checked using steel design rules. Calculations showed that the N-joints were governing for chord and brace sizes. Further numerical analysis on the N-joints using ANSYS 11.0 was carried out. Full scale experimental research was successfully carried out for validation of the numerical calculations. It is concluded that steel design rules predict the failure behavior and failure mode of the considered aluminium N-joints well. However, steel design rules overestimate the failure load by 8% for the truss configurations investigated.

Safety of fall arrest systems: A numerical and experimental study

2000 ◽  
Vol 214 (10) ◽  
pp. 1221-1233 ◽  
Author(s):  
F Drabble ◽  
D J Brookfield
Keyword(s):  
Numerical Analysis ◽  
Energy Balance ◽  
Experimental Tests ◽  
Balance Method ◽  
Restraint System ◽  
Analysis Method ◽  
Energy Balance Method ◽  
Analysis Technique ◽  
Fall Arrest ◽  
Better Than

Workers in elevated positions must be protected from falling or from the hazardous consequences of falls. Protection from falling can include fences, guard rails, etc., or a restraint system preventing the workers from reaching any point from which they can fall. However, protection from falling can be impractical and in such situations a fall arrest system (FAS) must be provided such that the fall does not cause injury to the worker or to others. This paper surveys prior work on the analysis of FASs including the energy balance method historically used. This method is limited to simple FASs where only one worker may fall. A novel numerical analysis technique for predicting the forces occurring in each component of an FAS during a fall is then described. Results from the numerical analysis are compared with results from experimental tests and with those from the energy balance method. It is shown that the numerical analysis technique predicts forces to within better than approximately 7 per cent, the method being conservative, whereas the errors shown by the energy balance method exceed 26 per cent. The new analysis method is also shown to be applicable to multiple falls.

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