MPC
Research Projects (2006-07)

Identifying Number

MPC-273

Project Title

Low-Cost Soft Crash Barriers

University

Colorado State University

Project Investigator

Paul Heyliger, CSU

External Project Contact

N/A

Project Objective

The objective of the project is to evaluate, study, construct, and test crash barriers composed of low-diameter wood elements that are inexpensive, easily replaced, and that yield significantly under external load.

Project Abstract

Most impact barriers, including guardrails, are typically designed subject to economic constraints, and many such systems perform extremely well. However, although these structural systems can provide excellent overall protection, they can often impart very large forces to both the vehicle and its occupants. This research study will design, analyze, and construct and test prototypical three-dimensional "soft" wood element networks that will provide both the necessary impact resistance while concurrently undergoing large deformations to soften the impact of the vehicle and occupants.

This project was funded at the seed level during 2002, which results in (1) preliminary numerical estimates of the mechanics of these systems, (2) a two-dimensional prototype frame tested under static conditions, (3) sufficient results to present in successful attraction of a USDA project on low-stiffness elastica wood frames, and (4) a submitted report and journal publication. The current proposal will extend the successful outcomes of this work into more sophisticated computational models for this class of structure, construct three-dimensional frames for analysis and testing, and initiate prototypical guard barriers that can be constructed at low cost and replaced with relative ease while maintaining the structural aspects of large deformation under load.

Task Descriptions

1. Develop three-dimensional computational model for the large deformation elastica behavior for small-diameter wood elements.
2. Construct and perform static deformation tests on three-dimensional structural frameworks.
3. Construct guidelines for general behavior of elastica frameworks for crash barrier applications.
4. Construct and test large-scale crash barriers during dynamic tests using either standard drop tests or car-impact simulations.

Milestones, Dates

Starting Date: July 1, 2006
Ending Date: June 30, 2007

Yearly and Total Budget

$63,322

Student Involvement

Nearly all funds will be used for support of graduate students, part-time post-doc support, and hourly undergraduate students.

Relationship to Other Research Projects

This work is an applied extension to our USDA funded work on elastica frames, which involves a much stronger theoretical component and an emphasis on smaller frameworks.

Technology Transfer Activities

Numerical models of these wood networks can also be used for other low-density fibrous composite applications, which may have additional uses in transportation such as biofibrous mesh reinforcement for rock-fall prevention on slope stability. It is anticipated that technology transfer will be achieved through multiple refereed journal publications and project reports. At least one PhD dissertation will be developed and several undergraduate students will also be used to construct the test specimens, giving a constructive educational impact to this work. A TLN seminar will be delivered by the graduate student during the spring of 2007.

Potential Benefits of the Project

These structural systems are almost non-existent but have tremendous potential impact and several areas of application. This includes (a) impact at single locations or in a continuous line along a guard-rail, (b) industrial damping, © packaging protection, (d) a biodegradable component for systems that are required for only a finite amount of time. These systems will be designed to take advantage of the low-cost and easy replacement nature of using inexpensive wood designed to deform rather than resist load with infinitesimal displacement. Further, federal agencies are currently searching for uses for soft small-diameter trees which are thinned out of dense forest land. These materials and their by-products could be incorporated into the proposed systems. Prototypes of three-dimensional systems will be a fixed deliverable at the end of the second year, along with design guidelines for at least two types of systems (discrete and continuous).

TRB Keywords

Crash Barriers, Guard Rails, Numerical Model, Structural Frames, Wood, Elastica