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Engineering, United States

Grujicic M.,Clemson University | Sellappan V.,Clemson University | Sellappan V.,Ozen Engineering Inc. | Arakere G.,Clemson University | And 5 more authors.
Multidiscipline Modeling in Materials and Structures | Year: 2010

Purpose - The purpose of this paper is to propose and analyse computationally a new concept for mechanical interlocking between metal and plastics. The approach utilizes some of the ideas used in the spot-clinching joining process and is appropriately named "clinch-lock polymer metal hybrid (PMH) technology." Design/methodology/approach - A new approach, the so-called "direct-adhesion" PMH technology, is recently proposed Grujicic et al. to help meet the needs of automotive original equipment manufacturers and their suppliers for a cost-effective, robust, reliable PMH technology which can be used for the manufacturing of load-bearing body-in-white (BIW) components and which is compatible with the current BIW manufacturing-process chain. Within this approach, the necessary level of polymer-to-metal mechanical interconnectivity is attained through direct adhesion and mechanical interlocking. Findings - In an attempt to fully assess the potential of the clinch-lock approach for providing the required level of metal/polymer mechanical interlocking, a set of finite-element based sheet-metal forming, injection molding and structural mechanics analyses is carried out. The results obtained show that stiffness and buckling resistance levels can be attained which are comparable with those observed in the competing injection over-molding PMH process but with an ∼ 3 percent lower weight (of the polymer subcomponent) and without the need for holes and for over-molding of the free edges of the metal stamping. Originality/value - The paper presents a useful discussion of clinch-lock joining technology's potential for fabrication of PMH load-bearing BIW components. © Emerald Group Publishing Limited.

Methods and computer readable media for designing an implant to support a bone of a person. Based on the daily activities of the person, one or more musculoskeletal loads applied to the bone are determined. Also, a set of characteristics of the implant, such as dimension, material, geometry, and shape of the implant, is selected. Then, a numerical simulation of the implant and the bone is performed to determine a physical status of the implant under the musculoskeletal loads. Subsequently, it is determined if the physical status meets one or more of preset failure conditions. If the determination is negative, the implant is taken as an optimized implant. Otherwise, at least one of the characteristics of the implant is modified and numerical simulation of the implant and the bone is repeated until an optimized implant is obtained.

Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.99K | Year: 2009

DESCRIPTION (provided by applicant): Virtual product design and assessment has become a valuable tool in the development and evaluation of new buildings (and consumer products) as well as the interior design of automobiles. While these processes are beginn ing to work well for whole body designs targeted at accommodating population anthropometries, particularly in an effort to reduce injuries associated with awkward postures (Corlett et al. 1980, Chang et al. 2003, Chaffin 2005, Perez 2005), they have not be en applied to hand tool or device design. It has been shown that repeated use of hand tools by individuals with hand dimensions significantly different than for which the tool was intended has resulted in an increased potential for hand-related injuries (C obb et al. 1996, Meagher 1987, Kar et al. 2007, Markison 2007), particularly when significant force is required to operate the tool (Sancho-Bru et al. 2003, Molteni et al. 2008). Virtual hand models have been ineffective in addressing such anthropometric t ool-fit issues. Current technological impediments related to available virtual hand models include (1) a lack of a solid geometry hand with accurate surface representation and accurate joint kinematics defined by centers of rotation, (2) a limited capacity in accounting for anthropometric scaling (e.g. the relationships between individual finger segment dimensions) (3) missing information on predicting how the hand grips objects and the forces applied during gripping, and (4) an inability to account for tis sue compliance (particularly at the finger tips and palmar surface). The proposed project intends to address these impediments by developing a 3D geometric hand model, to be integrated into the current CAD design software products used by design engineers (e.g., SolidWorks, ProE) to evaluate the interaction between the hand and a new product. The proposed Phase 1 research will result in a virtual hand model that specifically targets the first two impediments (listed above) and will establish a draft framewo rk (to be used to scope future research) for the necessary parameterization to address (3) and (4). At the conclusion of phase 1, a stand-alone software program with a scalable geometric hand representation with kinematically realistic articulating digits will be produced. The virtual hand model will be developed using the open-source SimTK core libraries (Sherman et al. 2005, Delp et al. 2007, Schmidt et al. 2008). The bones and joints of the hand will be modeled using rigid body structures to mathematical ly replicate laboratory recorded hand anthropometry, joint centers, and kinematics. The surface representation of the hand will be modeled using a similar method used by rigid body spring models (RBSM) (Kawai 1980). An integrated hand model, incorporating both the proposed surface-deformation/skeletal model and existing muscle models, would provide a powerful analysis tool for 1) understanding hand related injury mechanisms associated with grip posture and force and 2) optimizing tool design in-silico, prio r to workplace deployment. PUBLIC HEALTH RELEVANCE: There currently exist no methods for design engineers to assess prospective design changes in a virtual environment as related to the overall tool-hand fit with respect to different population hand sizes. This has led to hand tool designs that are inappropriate for a large number of users and whose repetitive use will result in an increased potential for injury (Meagher 1987, Markison 2007). The overall goal of this project is to develop a scalable, virtua l hand model that can be used to evaluate and determine appropriate hand-tool coupling interfaces, information that can be used to design hand tools to accommodate the hand sizes and hand shapes of end users.

Erdem Alaca B.,Koc University | Ozcan C.,Bogazici University | Ozcan C.,Ozen Engineering Inc. | Anlas G.,Bogazici University
Nanotechnology | Year: 2010

To address the necessity for a predictive computational tool for layout design in crack lithography, a tool for nanowire fabrication, a computational study is carried out using finite element analysis, where crack-free edge and crack-crack interactions are studied for various material combinations. While the first scenario addresses the ability to induce a controlled curvature in a nanowire, the latter provides an estimation of the minimum distance which can be kept between two straight nanowires. The computational study is accompanied by an experimental demonstration on Si/SiO2 multilayers. Finite element results are found to be well aligned with experimental observations and theoretical predictions. Stronger interaction is evident with a curved crack front modeling as well as with increasing first and decreasing second Dundurs' parameters. Therefore cracks can be packed closer with decreasing film stiffness. © 2010 IOP Publishing Ltd.

Grujicic M.,Clemson University | Arakere G.,Clemson University | Xie X.,Clemson University | LaBerge M.,Clemson University | And 3 more authors.
Materials and Design | Year: 2010

The problem of size/thickness optimization of a distal femoral-fracture fixation-plate is addressed computationally using a combined finite-element/design-optimization procedure. To obtain realistic physiological loading conditions associated with normal living activities (cycling, in the present case), a musculoskeletal multi-body inverse-dynamics analysis is carried out of a human riding the bicycle. While optimizing the design of the femoral-fracture locking-plate, realistic functional requirements pertaining to attain the required level of fracture-femur fixation and longevity/lifecycle were used. It is argued that these types of analysis should be used to complement pre-clinical implant-evaluation tests, the tests which normally include a limited number of physiological loading conditions and single pass/fail outcomes/decisions with respect to a set of lower-bound implant-performance criteria. © 2010 Elsevier Ltd.

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