An emerging change across the science, technology, engineering, and mathematics curriculum is the implementation of online, or virtual laboratories as supplements or replacements to both homework assignments and laboratory exercises. To test the effectiveness of such labs, a web-based virtual laboratory on the topic of torsion of engineered and biological materials was developed. The lab contains extensive data sets, videos of experiments, narrated presentations on lab practice and theory and assignments. Flexibility of use is built into the lab by providing the capability for the web-pages to be tailored to the needs of a particular institution. The lab was implemented and evaluated in a standard, sophomore level statics, and strength of materials course. Results of the evaluation show that the virtual lab is clear, helped students with their understanding of torsion concepts, and offered a number of benefits. However students also rated hands-on labs to be more fun and more interesting. ß

ABSTRACT:The polyimide HFPE-II-52 was developed at NASA Glenn Research Center for use as a matrix in high temperature composite materials. The unique properties of such composites stem largely from the performance of the matrix at high temperature. Thus, as part of a larger effort to study high temperature composite materials, the linear viscoelastic properties of HFPE are measured and a mathematical model of the properties is developed. In particular, storage, loss, and stress relaxation moduli were obtained from cyclic and transient loading experiments. A Prony series was fit to the relaxation modulus data. As a cross check, the fit to the relaxation modulus was converted to storage and loss moduli and compared with those measured directly. Effects of postcuring and of moisture on the properties are investigated as well. These results provide researchers with a constitutive model for HFPE-II-52 and provide some insight into the performance of HFPE matrix composites at high temperatures.