Contact Analysis for Coupling of Plates and Screws in Fracture Fixation of Cortical Bone

Internal fixation is a common treatment for bone fracture. Bone fracture occurs due to different reasons such as motor vehicle accidents, falling,…etc. The treatment is performed by fixing plate and screws to the fracture site. Lack of stability of the implants (plates and screws) may lead to delay in healing or failure of treatment. Micro-motion between the implant and the bone may cause formation of fibrous tissue around the screw which will lead to implant loosening. On the other hands, firm fixing of the conventional implants (Dynamic Compression Plates) may lead to delay resorption and delay in healing. Recently, Locked Compression Plates were introduced to get over the shortcomings of the existing Dynamic Plates. In Locked Plates the hole and screw head were threaded to provide more stability and reduce contact with the bone surface. In this communication we conducted computational analysis to compare the stability of both sets of implants. Results have revealed that Locked Plates provide more stable fixation and resistance to micro-motion. However, stress shielding might occur which will delay healing. Future designs of the Locked Plates can focus on improving stability and reducing damage to blood supply which will shorten the healing period. Computational analysis (finite element analysis) can be effectively used to guide these future designs

THEORETICAL ANALYSIS OF THE LEAKAGE THROUGH THE CEMENT LINE OF A SINGLE OSTEON

This work focuses on the Lacunar–Canalicular Porosity (PLC) of cortical bone which includes the osteons. Osteons are semicylindrical porous structures saturated with fluid within the bone and are approximately 250 role= presentation \u3eμ role= presentation \u3eμm in diameter. The outer boundary of the osteon is called the cement line. Some studies suggested that the cement line is less highly mineralized and produced evidence that it has less calcium and phosphorus and more sulfur than the neighboring bone lamellae. Most authors assume that the cement line is impermeable, while others assume that some canaliculi are crossing the cement line which will make it permeable to certain degree. The objective of this work is to develop a theoretical analysis to study the leakage through the cement line and its relationship with the pore pressure distribution. The theoretical analysis is developed using our previous analysis for osteon under harmonic loading with addition of leakage parameter. The leakage parameter varies from 0 to 1, where a value of 0 indicates free flow through the cement line and a value of 1 indicates no flow through the cement line. Experimental results could be compared to this developed theoretical solution to get in depth understanding of the effect of leakage on osteon poroelastic properties. Additionally, the developed theoretical solution will give insight into sensitivity of osteon pore pressure to leakage through the cement line

Intradepartmental Collaboration to Improve the Quality of Engineering Drawings Created by Students in Senior Design Project

Engineers use engineering graphics to describe their design, to exchange ideas, and to communicate with others. As an important communication tool, most engineering department commits at least two courses on engineering graphics. The mechanical engineering technology at the college offers three engineering graphics courses for its associate degree program. The objective is to give students opportunity to get familiar with different type of engineering graphics from 2D to 3D and from general graphics to mechanical engineering specific graphics gradually so they can apply these engineering graphics skills in their senior courses such as in machine design. Despite the extensive offering of engineering graphics courses to students, a review of students design work in senior design project of the machine design course revealed that students still lacked certain skills and understanding when creating their design models and working drawings. For examples, many students didn’t understand the difference between working drawings and the corresponding 3D objects, they had difficulty in creating sheet metal components and gears, and most importantly, and many students still treated engineering graphics work in product design as design of unrelated individual components instead of treating them as integral part of a system. In fall 2012 the instructor who teaches senior design project, started to collaborate with instructors who teach engineering graphics to address these issues mentioned above. Students were given a design project that require the students to create many common mechanical components used in product design such as gears, sheet metal components, and mechanical subsystems such as differential drive and steering system. Students not only have to pay attention on how to create these components correctly, they have to pay attention on the relationships among these components when they are assembled together. This gives students a better understanding on how to use engineering graphics in product design. The details concerning the implementation of intradepartmental collaborative work including assessment will be discussed this paper as well as in future papers

Comparative Analysis of 3D Printed Denture Resins with Traditional Denture Materials at the Micro Level

The aim of this experiment was to evaluate and identify compression strength between traditionally manufactured acrylic dentures and additive manufacturing resin dentures. Specifically, the dentures produced by Uhler Dental, its Reveal line were compared against samples produced on the Formlabs Form 2 SLA, Stereolithography, 3D printer using their Denture Teeth A2 resin to test compression strength to assure they are compatible with the occlusal forces in the oral cavity. Using the ZwickRoell tensile testing machine, it appeared that the acrylic dentures were half as strong as the resin dentures. Then we went ahead to and did a comparative analysis under a microscope to see the micro-properties such as the isotropic uniformity in the resin, layer adhesion, and the microstructure of the two different materials; in general, these two materials appear that resin denture teeth have lesser mean percent porosity values than the acrylic denture teeth. After doing both the compression test and a micro-level analysis under the microscope we have determined that the resin denture has the proper strengths and properties to handle the occlusal forces in a human oral cavity

Workforce Development Strategies in Additive Manufacturing

Additive Manufacturing (AM), also known as 3D Printing (3DP), is one of the newest manufacturing technologies with growing utilization in our daily life. Parallel to this growth, new materials, machines, and specific processes are being developed to produce parts in better-finished quality, at lower cost, and with shorter production time. However, workforce education in this evolving field has not advanced at the same pace as the technology, lacking proven curriculums, high-quality/accredited degree programs, and specialized advanced degrees. In this paper, some best practices established by the authors are introduced. The list is far from exhaustive but is proven to be effective in practice

Medical Dental Device: Biogeneric Implant Prototype

Teeth are lost due to tooth decay, injury, disease, or other causes. Today, dental implants extend the range of care to a variety of patients undergoing necessary prosthodontic rehabilitation. If the benefits of such treatments are to be maximized, then implants must be selected on logical basis and placed within the context of the full range of treatment modalities. However, modern dental implant systems are based on multiple components often leading to micro-movements which cause stress on the bone or bacterial infections, both of which compromise the success of osseointegration and consequently jeopardize the whole implant adaptation. Thus, a new idea of one-component immediate loading implant emerged to reduce the micro-movement, shorten healing time and number of visits, and contribute to lesser implant failures. The prototypes of the seven-fin trabecular structure implant will be customized using the design software and 3D printing. Next steps will focus on osseointegration, specifically on the best materials and techniques to induce bone formation at the osteotomy site, and on creating the printed implant prototype designed with specifications, measurements, and proportions in accordance with the morphology and function of the natural teeth

Advanced Design and Fabrication of Prosthetic and Medical Devices

The department of Mechanical Engineering and Industrial Design Technology (MEIDT) at City Tech is seeking to strengthening the skills of its students in manufacturing and design to respond to the urgent needs of the manufacturing industry in general and the prosthetic and medical devices (P&MD) industry in particular to high-skilled engineers and technicians and to provide a national model for advanced technology education. Medical Devices will include: (a) Surgical and Medical Instruments; (b) Surgical Appliances and Supplies; and (c) Dental Equipment and Supplies. The educational merit of the project is that it motivates students to do engineering rather than studying engineering. Students will get the opportunity to connect classroom experience to the medical device industry through intensive hands on experience in medical imaging and concepts of P&MD. Curriculum will be linked to practice so students will apply what they learn in the classroom in Computer Aided Design (CAD), Engineering Materials, Manufacturing Processes, Computer Aided Manufacturing (CAM), Mechatronics, Tolerance, Product Life Cycle and Management, and Engineering Analysis. Furthermore, the project will adopt advance STEM strategies such as Project-based-Learning and best strategies to teach STEM courses by moving from particular experience (design and manufacturing of medical devices) to general experience (design, manufacturing, materials,…etc). Additionally, the project will build on current ATE centers successful strategies to recruit female students to STEM through introducing them to bio-related projects. The technical merit of the project lies in providing students with the opportunity to collaborate with the industry to work in real-life projects

Senior Design Case Study: Application of System Engineering Concepts in the Design of a Router

System engineering (SE) is a multidisciplinary approach for the design, management, and realization of a complex system. In product development, SE is utilized on structuring a product development process into simple and collaborative activities that proceed throughout the entire product life-cycle, while at the same time, supporting engineers’ decision making. Project based engineering design classes are suitable for undergraduate students to study and practice the concepts of SE while solving real-world design problems. In this paper, we document the product development process, especially the structured design methodologies used in an undergraduate Senior Design project. Student learning outcomes are assessed and compared with previous semesters. We have observed overall satisfying student learning in nearly all aspects. Hence, we believe the multidisciplinary project helps students learn valuable knowledge of SE that is usually acquired through real world working experiences