Non-contact stress measurement in PET preforms

ABSTRACT

Residual stresses in PET preforms is thought to be an important cause in the stress cracking of blown bottles but there is no data yet that can be linked to stress and cracking. An important step in this link is the measurement of stresses in the preform base and neck region of the preforms. This paper reports on the usage of photoelastic methods to measure residual stresses in preforms. It is found that the residual stresses vary from preform to preform and how cracks develop is due to the qualitative and quantitative presence of residual stresses and its orientation.

GRAPHICAL ABSTRACT

KEYWORDS:

• Inspection
• preforms
• residual stresses
• longitudinal stress

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

RGR Prasath

RGR Prasath has 17 years of experience as Research Engineer. His areas of expertise are - measuring residual stress/strain experimentally in polymers, silicon wafers (electronic and solar grade) and glasses. He has also developed stress measurement systems both hardware and software that involves data acquisition and image processing.

Steven Danyluk

Steven Danyluk is the Morris M. Bryan, Jr. professor Emeritus at the George W. Woodruff School of Mechanical Engineering at the Georgia Insititute of Technology.  He is also the CEO of Polaritek Systems, Inc. a technology company specializing in the measurement of the mechanical aspects of polymer and semiconductor materials.

Steve Zagarola

Steve zagarola is the managing partner of Northwest center for Performance Excellance and the President of ZDM Group. He is a Six Sigma Master black belt with more than 25 years experience in the practical application of statistical and modern structured approaches to the optimization of manufacturing and transactional processes, quality systems and R&D. He authored the first plastic soft drink bottle specifications for The Coca-Cola Company in 1975. He holds patents for container design and testing methods.