Impact resistance of non-Newtonian fluids

(supervisor: Rudi Winter)

Nature of project: experimental, instrumental

Available to full-time physicists only.

Project description and methodology

This project concerns the impact resistance of non-Newtonian fluids[1] and is motivated by their potential use as a protective substance[2].

The objective of the project is to quantify the response of the fluid to sudden acceleration (including deceleration and change of direction) and its ability to divert stresses acting on an embedded object in order to protect it from damage.

In the course of the project, a test rig will be developed based on a device containing a strain gauge that can be subjected to accelerating movements. A suitable non-Newtonian fluid will be identified (e.g. oobleck[3] of a specific composition) and characterised to ensure reproducibility throughout the project.

Parameters that may be investigated include impact surface area, temperature and thickness of the fluid layer surrounding the embedded sensor/object.

A successful project will develop beyond the above in one/some of the following directions:
This project offers the opportunity for some theoretical work by model fitting the measured data to a number mathematical models[1,4] for different types of non-Newtonian fluids such as the Ostwald-de Waele power law relationship with the shear rate.

Once comprehensive data have been established, a demonstration study of the protective qualities of the non-Newtonian fluid may be devised where a delicate object (e.g. an egg) is subjected to (and, hopefully, protected from) impact.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: For the Y4 version of the project, the student will be expected to devise a model prediciting the strains (and perhaps their direction) for a given set of experiment parameters. This will be based on the experimental findings and allow prediction of the effect of impacts outside the studied parameter range by extrapolation.

Initial literature for students:

  1. HA Barnes et al.; An Introduction to Rheology; Elsevier 1989
  2. FJ Galindo-Rosales et al.; Mater & Design 82 (2015) 326
  3. http://www.wikihow.com/Make-Oobleck
  4. Y Tomita; Bull. JSME 2 (1959) 469

Novelty, degree of difficulty and amount of assistance required

Qualitatively, the properties of oobleck are quite well established, so there is no doubt that the project will be deliverable in principle. The attempt to quantify strain goes beyond what is usually attempted in demonstration studies in this area, so there is a potential genuinely to extend our understanding of non-Newtonian fluids in this respect.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Concept for workable test rigend of November
Parameter space for experiment planned and prioritisedChristmas
Parameter space covered comprehensively by experimentsend of February
Modelling or Demonstration egg impact experimentEaster

Students taking this project will have to submit a full risk assessment form