empty and full bottles must travel at steady speeds down conveyors. They must hold their shape while being filled, and stay upright when they hit guide rails and gates on the conveyor. In the past, analysts would test bottle prototypes on an oval test conveyor nicknatned Racetrack. Results were reliable, but the tests were time consuming.
^ o speed bottle design, our engineers developed a method of analyzing bottles to determine their structural performance. Our Virtual Package Simulation (VPS) system uses Hypermesh from Altair Engineering Inc., Troy, Mich., as a preprocessor and Abaqus FEA software, from Abaqus Inc., Pawtucket, R.I. Because nearly all Proctor & Gamble (P&G) bottles share common features, such as being filled from the top, having thin walls, and using plastic materials, VPS includes several predefined load cases. These spell out standard loads and boundary conditions, what bumps and impacts to expect, and proper analyses procedures. The system is invaluable because P&G uses hundreds of different bottles, and every month we tweak old designs and evaluate new ones. Proposals include new weights and sizes that range from 4-oz bottles of Old Spice to 2-gallon botdes of Tide.
PACKAGING FEA
Typical design changes include lowering the center of gravit}' on empt\- and full bottles to improve travel on the conveyor belt, strengthening bottle walls to prevent deformation on impact, and modifying geometry to better witlistand fill loads. A typical analysis starts after importing the CAD model of a botde througli IGES into the meshcr for preprocessing. Each design is meshed and given a thickness based on bottle .specifications or t)n the results of a blow-molding simulatitjn, also created in house. The meshcr lets bottle designers select appropriate load cases to analyze with Abaqus/Explicit. Simulations can have, for example, top-loaded bottles bumping into gates while empt\' or tilled, accumulating along the conveyor, and moving with an assigned speed. Engineers specify conveyor speed, gate heights, load values, and other production equipment. Finally, job-management software transfers all these inputs to Abaqus, which runs consecutive analyses of the meshed bottle designs. Full analysis generally takes 12 hr using six CPUs.
THE RAYOFF
The Virtual Racetrack has produced a number of immediate benefits, such as shorter design cycles than previously possible. It also tests a wider range of proposals at lower costs. This lets our engineers evaluate more designs, thus promoting innovation. In addition, VPS applies standardized meshes and analyses for greater uniformity of methods and results which, in turn, instills a high level of design confidence. Our team has analyzed hundreds of bottles using the Virtual Racetrack and VPS system. When designs get the goahead, the bottles perform as predicted. Engineers arc now working to reduce the run time for the Virtual Racetrack from 12 hr to three. Our company plans to license the Virtual Package Simulation system, along with the Virtual Racetrack and a blowmolding simulation tool. Of course, such systems will not replace the experience of seasoned analysts, but it will help them get accurate results more quickly. •
Building a better bottle
David Henning
Manager of Package Analysis Procter & Gamble Cincinnati, Ohio
Simulation shows how bottles fill and stack and whether they'll tip over on a conveyor.
Packaging Design Engineer • June 2004 • 21
As mouthwash bottles accumulate at the gate, they tip back and forth against each other but do not fall over. Designs that tip over typically have their centers of gravity lowered to ensure better balance during travel and on impact.
20 • June 2004 • Packaging Design Engineer
A meshed model of a Tide detergent bottle was created in Altair's Hypermesh. Blue areas are thinnest; red are thickest. P&G engineers use Abaqus FEA software in the Virtual Package Simulation system to assess effects of different loads and forces on bottles traveling along a packaging conveyor.
In this simulation, mouthwash bottles travel down a conveyor toward an impact gate. An Important FEA task is to determine the effects of impact and bottle accumulation as they strike the gate at the right. Abaqus/Explicit performs a dynamic simulation of the travel and impact.