Drop Testing in Simulation Analysis

We have all heard the old adage ‘you wait an age for a bus then three turn up at once’. In the world of simulation, the same thing seems to happen when we speak to potential prospects about virtual prototyping and what’s possible. It was airbags a few years back. We were asked by a few different people if could we not only simulate the inflation process, but also how it was folded up in the first place. Now it seems Drop testing is the hot topic. Not drop testing of phones or other electrical devices but plastic bottles and their contents.

Although our prospects don’t share a common vision there are many similarities in their specific applications. The spectrum is wide; exploring Additive Manufacturing of soft tools for small initial batch samples, to simulating the blow moulding process and how this constrains the aesthetic freedom of the designer. (If you are interested in Additive Manufacturing then please read our earlier blog). But whatever the motivation and specific design task to hand the benefits of simulation are still obvious – you need fewer trial runs and tool modifications, and gain an understanding of the critical design and process parameters. And the better the quality of the solution the more effective this process is. It’s no good using a simple analysis approach if the behaviour of the contents influences what happens to the bottle, and we all know that that’s going to be critical in most situations.

Abaqus is well placed to tackle these sorts of projects as it can handle the full spectrum of physics and combinations of physics which occur in extreme high speed events such as drop tests.

• Large deformation
• Contact including parts separating and then colliding with each other again.
• Fluid structure interaction (FSI);  liquids sloshing internally in the container using CEL (Coupled Eularian Lagrangian) solvers
• Non- Linear material behaviour which can include permanent deformations and even ultimate failure.

Our clients were also interested in these more involved projects..

• Drop testing from a specific height or heights with the bottle positioned at 45 degrees.
• Push on and pull off characteristics of bottle tops.
• Label application – wrinkling and deformation during application and handling
• Filling and the structural implications of this process
• Transportation, shrink wrapping, manual handling and how resistant packages are to this.

As I said previously why simulation, rather than more tests? As with any design process being able to improve the design and fine tune many aspects before tooling is ordered is a massive benefit. But unlike many other more mainstream engineering projects the aesthetics of a bottle are critical; they need to catch the consumers eye. Which brings the age old conflict between form and function into stark contrast (unless, of course, you are a student of Walter Gropius). Using simulation to explore and exploit the art of the possible may not only help settle the arguments between designers and engineers, but allow them to come up more creative solutions.