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Strain gages have been widely used for measuring strain or deformation. They are very reliable and accurate. However, for application on fabric material, strain gages have their limitations. In this paper, digital image correlation (DIC) is used to measure the deformation around the rear window on a convertible top. The test needed to be non destructive, the vehicle and convertible top could not be damaged. The deformation or strain measured on the fabric was used to estimate the force experienced at the interface between the glass and the fabric during an opening/closing application. A speckle pattern was created on the convertible fabric where deformation was to be measured with washable paint. The image of the measured area was first recorded. The convertible top was then latched down and the fabric was stretched. A second image was recorded again. Based on the two images, the deformation/strain between the two conditions was measured.

Over the past twelve years the Auto/Steel Partnership (A/SP) Tube Hydroforming Materials and Lubricants Team has been conducting projects to aid the implementation of tubular hydroforming in automotive applications. The approach taken has been to initially gain a basic understanding of the hydroforming process and potential issues and to then extend learning to real world applications of increasing complexity. The experimental project investigations have encompassed various steel grades with a recent focus on advanced high strength steel (AHSS) and tailor welded tubes (TWTs) in free expansion and corner fill processes using several types of lubricants. Project plans are developed based on identified knowledge gaps, barriers to implementation and technology needs as follows: Effects of forming operations prior to hydroforming including tube making, pre-bending and pre-forming. Forming limits (e.g. forming limit diagrams (FLDs)) and other failure criterion.