Altered pressure in the developing left ventricle (LV) results in altered morphology and tissue material properties. Mechanical stress and strain may play a role in the regulating process. This study showed that confocal microscopy, three-dimensional reconstruction, and finite element analysis can provide a detailed model of stress and strain in the trabeculated embryonic heart. The method was used to test the hypothesis that end-diastolic strains are normalized after altered loading of the LV during the stages of trabecular compaction and chamber formation. Stage-29 chick LVs subjected to pressure overload and underload at stage 21 were reconstructed with full trabecular morphology from confocal images and analyzed with finite element techniques. Measured material properties and intraventricular pressures were specified in the models. The results show volume-weighted end-diastolic von Mises stress and strain averaging 50–82% higher in the trabecular tissue than in the compact wall. The volume-weighted-average stresses for the entire LV were 115, 64, and 147 Pa in control, underloaded, and overloaded models, while strains were 11, 7, and 4%; thus, neither was normalized in a volume-weighted sense. Localized epicardial strains at mid-longitudinal level were similar among the three groups and to strains measured from high-resolution ultrasound images. Sensitivity analysis showed changes in material properties are more significant than changes in geometry in the overloaded strain adaptation, although resulting stress was similar in both types of adaptation. These results emphasize the importance of appropriate metrics and the role of trabecular tissue in evaluating the evolution of stress and strain in relation to pressure-induced adaptation.

This paper describes a virtual reality application that performs fast stress reanalysis coupled with virtual reality and haptics that allows rapid evaluation of multiple designs throughout the product design process. The Interactive Virtual Design Application (IVDA) allows the engineer to interactively explore new design geometry while simultaneously examining the finite element analysis results. In the presence of other parts in the assembly, the new shape can be analyzed and modified, taking into consideration mating part fits. This approach supports concurrent product design and assembly methods prototyping. A "two-step" approach utilizing Taylor series approximations and Pre-conditioned Conjugate Gradient methods is used to perform quick reanalysis during interactive shape modification. The virtual environment provides an immersive threedimensional workspace. Haptics are used to provide feedback of the stress gradient as the part geometry is changed, thus facilitating the designer's understanding of the impact of shape change on product performance. ABSTRACT This paper describes a virtual reality application that performs fast stress reanalysis coupled with virtual reality and haptics that allows rapid evaluation of multiple designs throughout the product design process. The Interactive Virtual Design Application (IVDA) allows the engineer to interactively explore new design geometry while simultaneously examining the finite element analysis results. In the presence of other parts in the assembly, the new shape can be analyzed and modified, taking into consideration mating part fits. This approach supports concurrent product design and assembly methods prototyping. A "two-step" approach utilizing Taylor series approximations and Pre-conditioned Conjugate Gradient methods is used to perform quick reanalysis during interactive shape modification. The virtual environment provides an immersive three-dimensional workspace. Haptics are used to provide feedback of the stress gradient as the part geometry is changed, thus facilitating the designer's understanding of the impact of shape change on product performance.

developed a methodology to support low clearance immersive, intuitive manual assembly while using low-cost desktop-based Virtual Reality systems with haptic force-feedback. Research interests: virtual reality (VR) applications in mechanical design, design methodology and engineering education. Dr. Anne M Lucietto, Purdue UniversityDr. Lucietto has focused her research in engineering technology education and the understanding of engineering technology students. She teaches in an active learning style which engages and develops practical skills in the students. Currently she is exploring the performance of engineering technology students in the classroom and using that knowledge to engage them in their studies. Dr. Lucietto is a Fellow in the Society of Women Engineers, Senior Member of IEEE, and a member of other professional organizations.Dr. Jacquelyn Kay Nagel, James Madison University Dr. Jacquelyn K. Nagel is an Assistant Professor in the Department of Engineering at James Madison University. She has eight years of diversified engineering design experience, both in academia and industry, and has experienced engineering design in a range of contexts, including product design, bio-inspired design, electrical and control system design, manufacturing system design, and design for the factory floor. In 2012, Dr. Nagel was recognized by the National eWeek Foundation and IEEE-USA as one of the New Faces of Engineering for her pioneering work in bio-inspired design. In 2013, she attended the National Academy of Engineering's (NAE) fifth Frontiers of Engineering Education (FOEE) symposium where she was recognized as an innovative engineering educator. Dr. Nagel earned her Ph.D. in mechanical engineering from Oregon State University and her M.S. and B.S. in manufacturing engineering and electrical engineering, respectively, from the Missouri University of Science and Technology.Dr. Diane L Peters P.E., Kettering University Dr. Peters is an Assistant Professor of Mechanical Engineering at Kettering University.

College of Engineering Dr. Dusek joined Olin in 2017 from Harvard where he served as a postdoctoral fellow in the Self-Organizing Systems Research Group at Harvard's John A. Paulson School of Engineering and Applied Sciences under faculty supervisor Professor Radhika Nagpal developing miniature underwater vehicles for marine swarm applications. Prior to joining Harvard, he held several teaching and research roles at the Massachusetts Institute of Technology (MIT) and the Singapore-MIT Alliance for Research and Technology's Center for Environmental Sensing and Modeling (CENSAM). Dr. Dusek received his Ph.D. from MIT in Mechanical and Ocean Engineering, an M.S. in Ocean Engineering from MIT and a B.S. from Florida Atlantic University in Ocean Engineering as well.

This paper investigates the effect of pointshell shrinking and feature size on manual assembly operations in a virtual environment with haptic force feedback. Specific emphasis is on exploring methods to improve voxelbased modeling to support manual assembly of low clearance parts. CAD parts were created, voxelized and tested for assembly. The results showed that pointshell shrinking allows the engineer to assemble parts with a lower clearance than without pointshell shrinking. Further results showed that assemble-ability is dependent on feature size, particularly part diameter and clearance. In a pin and hole assembly, as the pin diameter increases, for a given percent clearance, assembling low clearance features becomes difficult. An empirical equation is developed to guide the designer in selecting an appropriate voxel size based on feature size. These results advance the effort to improve manual assembly operations via haptic feedback in the virtual environment. ABSTRACTThis paper investigates the effect of pointshell shrinking and feature size on manual assembly operations in a virtual environment with haptic force feedback. Specific emphasis is on exploring methods to improve voxel-based modeling to support manual assembly of low clearance parts. CAD parts were created, voxelized and tested for assembly. The results showed that pointshell shrinking allows the engineer to assemble parts with a lower clearance than without pointshell shrinking. Further results showed that assemble-ability is dependent on feature size, particularly part diameter and clearance. In a pin and hole assembly, as the pin diameter increases, for a given percent clearance, assembling low clearance features becomes difficult. An empirical equation is developed to guide the designer in selecting an appropriate voxel size based on feature size. These results advance the effort to improve manual assembly operations via haptic feedback in the virtual environment