Nov_Dec_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 2 0 3 1 T he automotive and energy in- dustries are currently experi- encing major global pressure to reduce waste and carbon emis- sions and increase the recyclability of products and materials. These chal- lenges demand the development of new materials, such as lightweight composites and metals, and new processes, including 3D printing and other forms of additive manufactur- ing. Testing methods are constantly evolving to keep up with the speed of innovation in these areas. Trends in testing equipment include devel- opments in hardware and software. On the hardware side, these advanc- es include test frames and grips offer- ing excellent mechanical alignment, data acquisition electronics provid- ing higher bandwidths and sampling rates, and non-contact strain mea- surement. Major recent software de- velopments include the use of touch operation and database integration. COMPOSITES TESTING New continuous-fiber com- posites based on thermoplastic matrix materials provide significant performance benefits over tradi- tional thermoset materials, as they can be tougher and more resistant to impact damage. The processing times for thermoplastic composite materials are much shorter than those of ther- moset materials, which lends them to mass production rather than batch pro- duction. They are also easier to recycle. The testing of these materials presents new challenges, as it is difficult to bond protective tabs to the ends of speci- mens to prevent damage from the grips (leading to premature failure during alloys for use in automotive struc- tures. Automotive bodies have tra- ditionally been manufactured from press-formed sheet metal, but alu- minum is increasingly being used to reduce vehicle weight and emis- sions. Tensile testing is widely used to determine the mechanical prop- erties of sheet metals during press forming, and an important param- eter for determining the formability is the plastic strain ratio or r-value. The r-value is the ratio of true strain in the width direction to true strain in the thickness direction when a sheet material is plastically de- formed. Determination of r-value requires the simultaneous mea- surement of axial and transverse strain during a tensile test. Trans- verse strain has traditionally been measured using mechanical exten- someters at one of two points only; however, as many of the aluminum alloys exhibit inhomogeneous de- formation, a single or two-point width measurement results in a large scatter in the r-value. For this reason, the preferred method is to base the width strain measure- ment on the average width of the specimen. The recently introduced AverEdge32 option for the Instron AVE2 non-contact video extensometer pro- vides this capability. DIGITAL IMAGE CORRELATION Another exciting extension of non-contact video-based strain tech- nology is full-field strain measurement using digital image correlation (DIC) techniques. DIC is a strain measure- ment technique that works by captur- ing a series of images throughout a test EMERGING TRENDS IN MATERIALS TESTING Recent advances in hardware and software provide materials testers with improved productivity and enhanced capabilities. TECHNICAL SPOTLIGHT Composites testing system. a test). Overcoming these difficulties has involved the development of new specimen types and the use of smooth high-friction surfaces on grip jaw faces. This combination is expected to provide reliable test data while improving pro- ductivity by reducing specimen prepa- ration time. FORMABILITY TESTING One example of how new appli- cations drive testing requirements is the formability testing of aluminum