Integrating Design Throughout The Mechanical Engineering Curriculum: A Focus On The Engineering Clinics

At Rowan University, we have infused design into the curriculum through an eight-semester course sequence called the Engineering Clinic. Through this experience students learn the art and science of design in a multidisciplinary team environment. While many engineering programs currently include a Capstone Design course taken near the end of the college career to meet the design needs, Engineering Clinic at Rowan allows students to hone their design skills throughout their four-year career. This paper will describe in further detail the objectives and execution of each year in the design sequence, types of projects and how the Clinics complement traditional core courses in the curriculum. Impacts and benefits of the Clinics on students and faculty are discussed, as well as comparative data of Rowan Mechanical Engineering students and their peers nationally

Endothelial dysfunction and vascular disease

The endothelium can evoke relaxations (dilatations) of the underlying vascular smooth muscle, by releasing vasodilator substances. The best characterized endothelium-derived relaxing factor (EDRF) is nitric oxide (NO). The endothelial cells also evoke hyperpolarization of the cell membrane of vascular smooth muscle (endothelium-dependent hyperpolarizations, EDHF-mediated responses). Endothelium-dependent relaxations involve both pertussis toxin-sensitive G i (e.g. responses to serotonin and thrombin) and pertussis toxin-insensitive G q (e.g. adenosine diphosphate and bradykinin) coupling proteins. The release of NO by the endothelial cell can be up-regulated (e.g. by oestrogens, exercise and dietary factors) and down-regulated (e.g. oxidative stress, smoking and oxidized low-density lipoproteins). It is reduced in the course of vascular disease (e.g. diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively loose the pertussis toxin-sensitive pathway for NO release which favours vasospasm, thrombosis, penetration of macrophages, cellular growth and the inflammatory reaction leading to atherosclerosis. In addition to the release of NO (and causing endothelium-dependent hyperpolarizations), endothelial cells also can evoke contraction (constriction) of the underlying vascular smooth muscle cells by releasing endothelium-derived contracting factor (EDCF). Most endothelium-dependent acute increases in contractile force are due to the formation of vasoconstrictor prostanoids (endoperoxides and prostacyclin) which activate TP receptors of the vascular smooth muscle cells. EDCF-mediated responses are exacerbated when the production of NO is impaired (e.g. by oxidative stress, ageing, spontaneous hypertension and diabetes). They contribute to the blunting of endothelium-dependent vasodilatations in aged subjects and essential hypertensive patients. © 2008 Scandinavian Physiological Society.postprin

A network description of the non-Gaussian stress-optic and Raman scattering responses of elastomer networks

The ability to measure orientation in dual or multi-phase materials is of current relevance in the study conthe constitution and deformation characteristics of the separate phases in many technologically important polymeric systems. Raman spectroscopy is a very useful tool in this regard because separation of the scattered Raman intensities by phase is possible and because it can be used accurately on thick specimens. A three dimensional network model concept used previously to describe the stress and birefringence reponses of elastomers is extended to describe the components of the Raman tensor for amorphous elastomers under general finite deformations. The utility of the model is verified via its ability to predict the finite deformation responses of elastomeric networks under large shear deformations. Polydimethylsiloxane (PDMS) networks are tested to large deformations in uniaxial compression and in shear for comparison with the theory. Simultaneous displacement, load and optical retardation data are collected using apparatus specially designed to allow optical access throughout the deformation tests. The importance of properly accounting for finite rotations when relating the computational results to the experimentally measured optical data is discussed. The proposed network description of the Raman tensor is also compared to Raman intensity in the literature on polyethylene terephthalate (PET). The results indicate that the theory accurately predicts the anisotropic Raman tensor components over the full range of deformation for which data are available.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41702/1/707_2005_Article_BF01170305.pd

Experimental, analytical and computational investigation of bimodal elastomer networks.

Advances in the synthesis of macromolecular materials have led to the creation of special classes of elastomers called bimodal because of their bimodal distributions of linear starting oligomers. Numerous studies on these materials have documented anomalous increases in ultimate strength and toughness at certain mixture combinations of the constituents but have not yet identified a cause for this behavior. In addition, the ability to predict optimal mixtures still eludes polymer chemists. Constitutive models for the behavior of bimodal materials are also unable to predict material behavior, but instead tend to capture results using complicated curve fitting and iterative schemes. This thesis uncovers topological and micromechanical sources of these enhanced properties using periodic, topological simulations of chain-level network formation and develops a constitutive model of the aggregate bimodal network. Using a topological framework, in conjunction with the eight-chain averaging scheme of Arruda and Boyce, this work develops optical and mechanical constitutive models for bimodal elastomers whose results compare favorably with data in the literature. The resulting bimodal network theory is able to predict material response for a range of bimodal compositions using only two sets of data, a direct improvement over previous models. The micromechanics of elastomeric deformation and chain orientation as described by the eight-chain model are further validated by comparing optical and mechanical data generated during large deformation shear tests on unimodal materials with finite element simulations. In addition, a newly developed optical anisotropy model for the Raman tensor of polymeric materials, generated using an eight-chain unit cell model, is shown to compare favorably with tensile data in the literature. Results generated using NETSIM, a computer program developed in this thesis, have revealed naturally occurring, self-reinforcing topological features associated with experimentally observed increases in ultimate strength and toughness. The ability to predict increases in the populations of these topologies allows for the prediction of optimal bimodal mixtures and the definition of a metric of network optimality. The sol and gel fraction predictions from NETSIM also compare well with results obtained from experimental network synthesis and previous computational simulations. After formation, each molecular chain is assigned a modified entropic force-stretch law and the undeformed network is annealed, clearly illustrating how initial chain length distributions in bimodal materials deviate from the r.m.s. assumption. The results of computational annealing also highlight several structural features that have been observed experimentally in the literature. Results of the computational deformation of simulated, three dimensional networks show enhancements to strain hardening in networks with compositions similar to those which exhibited enhanced toughness in experiments. These enhanced, simulated networks also show increases in the orientation versus stretch response over compositionally similar networks. Orientation response results support previous experimental results. Increased occurrence of the doubled connection topology is found to enhance strain hardening in simulated networks and to be a positive factor in enhanced strain energy seen in experiments. The density of single cyclics, while having a positive correlation in the enhanced strain energy seen in experiments appears to negate the effect of increased populations of doubled connections in simulations.Ph.D.Applied SciencesMaterials scienceMechanical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132025/2/9938559.pd

Deposition Controlled Magnetic Alignment in Iron-PLA Composites

By manipulating the print plane, infill direction, and geometry of Fused Filament Fabricated (FFF) iron-PLA composite parts, the alignment of their magnetic axes can be influenced. FFF printing allows control of deposition direction, which affects the arrangement of the iron within the composite part in ways that induce preferred magnetic orientation, the so-called easy axis. Qualitative results show the direction of deposition of the composite iron-PLA filament has significant effects on the response of the printed parts to an external magnetic field. Results further show that across different geometries, the easy axis of a printed part can be prescribed by setting the print plane and infill direction parallel to the desired orientation. Expected part geometry effects, along with the print plane and infill influences, suggest the phenomenon can be modeled using multi-scale demagnetizing field theories to print magneto-sensitive devices that can perform localized, controlled actuation in a uniform magnetic field.Mechanical Engineerin

Digital Imaging Experiences for Undergraduate Engineering Students

Our project is an effort by a multidisciplinary team of engineering faculty members at Rowan University to integrate digital imaging technology (DIT) into the undergraduate engineering curriculum. It builds upon the experience and interest of faculty to promote new topics and innovative methods of teaching. The work is an effort to provide students with the skills directly relevant to the evolving needs of the industry and the marketplace. Projects involve the development of digital imaging curriculum and focus on the creation of a leading edge digital imaging laboratory/studio to facilitate the use of nontraditional learning approaches that encourage interactive learning, team building, and creative problem solving among students and instructors. A number of visual experiemtns will be developed and used to introduce students to the multidisciplinary engineering principles and use of DIT. Some of these activities will be used for K-12 outreach activities. Though our dissemination efforts we will encourage other schools to adopt our curriculum and modules to enhance their undergraduate curriculum and to promote engineering education outreach opportunities

Design Integrated in the Mechanical Engineering Curriculum: Assessment of the Engineering Clinics

At Rowan University, design has been infused into the curriculum through an eight-semester course sequence called the Engineering Clinics. Through this experience, students learn the art and science of design in a multidisciplinary team environment and hone their design skills throughout their 4-year career. This paper describes the objectives of the clinics, types of projects, and how the clinics complement traditional core courses in the curriculum. Impacts and benefits of the clinics on students and faculty are discussed, including retention and graduate study rates comparing Rowan University mechanical engineering students to their peers nationally. An assessment of the clinics is presented based on survey data and accreditation objectives and outcomes. Survey data from students were assessed to determine levels of students\u27 satisfaction and confidence based on the clinics. Results of alumni and employer surveys also provide valuable feedback for assessing and improving the clinics as well as confirmation of the impact of clinics after graduation. Survey data are discussed along with challenges of the clinics at Rowan and adaptability of them at other institutions. Overall, the clinics are a positive and integrated design experience in the curriculum and assist students in achieving the program objectives