Three Finnish associates, Tehomet Ltd, Fibrocom Ltd and Mikkeli Polytechnic Research Center YTI developed an internationally awarded energy absorbing lighting column product family in 2005. The design and dimensioning were completed with static FEM computations, preliminary impact tests and full-scale impact tests made by YTI and HUT.
However, the full scale impact tests are very expensive and time consuming, and they do not help very much in design optimization, since the test series must be kept as short as possible due to economical facts. So, YTI contacted CompMechLab to examine the crash mechanics in more detail and to be able to easily vary the product parameters for product optimization. CompMechLab objective was to develop FE models of lighting columns with sufficient energy absorbing properties, to obtain simulated crash test deceleration curves that are consistent with real car tests and to provide design and optimization guidelines for new columns.
FE system LS-DYNA is used in this project to perform contact-impact non-linear dynamic analysis of the construction. 3-D FE model spatial discretization is achieved by the use of shell and solid elements. Developed 3-D CAD and FE models of different types of columns allowed simulating several nonlinearities: dynamic impact at different vehicle speed, plasticity in column and vehicle parts, contact interaction between simulated objects, progressive damage in column laminates.
3D FE model of real car prototype based on FHWA/NHTSA National Crash Analysis Centerprototype includes radiator, engine, front and rear suspensions, brake system and many other parts with ability of contact interaction and nonlinearities in material behavior. Prototype design was debugged to make approximate similarity with car in experiment. Column 3-D FE model includes column stand, reinforced composite laminates, bracket with lanterns (single or double). Totally 216 different materials considered in car prototype with lighting column model.
The FE results, obtained with these models, showed that correctness of FEM-computations approves with that experiment maximal deviation stand in 14% value, and a good correlation between experiment and simulated deceleration curves.
The resultant simulated deceleration curves allowed calculating head injury criteria (HIC) estimate for all columns crush tests. All HIC values are below injury risk that shows a safe impact in all column types, and it is important to emphasize that all values are acceptable with safety standards for children and adults. Computed HIC values combined with maximal deceleration values provided validity of safety estimation.
JEC Composite Show, Paris
Tehomet Oy's channel composite lighting pole won a award in the Eneregy and Indutry category at the JEC Composite show in Paris in 2006.
Quateted from website (http://www.jeccomposites.com/):
"Lighting pole with controlled energy absorption characteristics to make impacts with vehicles less dangerous.Thanks to the composite pole's channel structure, it was possible to combine lower weight, high strength, high static rigidity, good energy absorption properties, and excellent impact behaviour, and still maintain competitive production costs. The pole can blend in with the urban landscape. Given Europe's specific impact standards
- the pole achieved the best EN 12767 classification - the European market is being targeted".
Additional materials:
The impact simulation of crash safe composite lighting columns.
Abstract, images and simulation results. PDF, 900 Kb.
LS-DYNA simulation and experiment comparison. Part 1. GIF, 2.98Mb. Download
LS-DYNA simulation and experiment comparison. Part 2. GIF, 5.22Mb. Download Reads: 2426
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