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Articles 1 - 14 of 14

Full-Text Articles in Engineering

Tibiocalcaneal Kinematics Of Barefoot Versus Shod Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg Nov 2000

Tibiocalcaneal Kinematics Of Barefoot Versus Shod Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg

Mechanical Engineering Faculty Publications

Barefoot running kinematics has been described to vary considerably from shod running. However, previous investigations were typically based on externally mounted shoe and/or skin markers, which have been shown to overestimate skeletal movements. Thus, the purpose of this study was to compare calcaneal and tibial movements of barefoot versus shod running using skeletal markers. Intracortical bone pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The subjects ran barefoot, with a normal shoe, with three shoe soles and two orthotic modifications. The three-dimensional tibiocalcaneal rotations were determined ...


Contributions Of Proximal And Distal Moments To Axial Tibial Rotation During Walking And Running, T. L. Bellchamber, Antonie J. Van Den Bogert Nov 2000

Contributions Of Proximal And Distal Moments To Axial Tibial Rotation During Walking And Running, T. L. Bellchamber, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The purpose of this study was to determine the cause and effect relationship between tibial internal rotation and pronation of the foot during walking and heel–toe running. This would allow predictions of orthotic effectiveness in reducing knee pain related to excessive internal tibial rotation. Kinematic and force plate data were collected from twenty subjects performing ten running and ten walking trials across a force plate. Using a least-squares algorithm, attitude matrices for each segment in each frame were obtained and the angular velocity vector of the tibia was calculated. The intersegmental moment at the ankle was calculated from ground ...


The Effects Of Patch Properties On The Debonding Behavior Of Patched Beam-Plates, Anette M. Karlsson Oct 2000

The Effects Of Patch Properties On The Debonding Behavior Of Patched Beam-Plates, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The debonding characteristics of patched structures are investigated in this study by means of an analytical model. In particular, the effects the lay-up sequence and edge tapering of a carbon-reinforced epoxy patch, as well as the beveling of an aluminum patch, have on the initiation, stability, and extent of the debonding are considered. The results presented show that both the degree of edge-tapering and the patch properties must be carefully selected in order to optimize the patched structure. It is also shown that when designing a patched system, it is important to model the correct boundary and load conditions to ...


The Influence Of Orthotic Devices And Vastus Medialis Strength And Timing On Patellofemoral Loads During Running, R. R. Neptune, I. C. Wright, Antonie J. Van Den Bogert Oct 2000

The Influence Of Orthotic Devices And Vastus Medialis Strength And Timing On Patellofemoral Loads During Running, R. R. Neptune, I. C. Wright, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Objective. To use a musculoskeletal model and simulation of running to examine: (1) the influence of two commonly prescribed treatments for patellofemoral pain (vastus medialis oblique strengthening and orthoses) and (2) the functional significance of timing differences between vastus medialis oblique and vastus lateralis on lateral patellofemoral joint loads.

Design. A three-dimensional musculoskeletal model of the lower extremity was used to simulate running at 4 m/s.

Background. Repetitive and excessive joint loading is often associated with overuse injuries that require clinical treatments to reduce pain and restore function. Affecting one in four runners, patellofemoral pain is one of the ...


On Thermal Buckling Of Patched Beam-Plates, Anette M. Karlsson, W. J. Bottega Aug 2000

On Thermal Buckling Of Patched Beam-Plates, Anette M. Karlsson, W. J. Bottega

Mechanical Engineering Faculty Publications

The behavior of uniformly heated plates is considered for the situation where a patch is adhered over a region of the structure. A variational formulation results in a self-consistent set of equations and conditions, which governs the response of the system. The nonlinear problems are solved analytically, yielding exact results within the context of the mathematical model employed. A stability criterion is established for the class of problems considered, based on the second variation of the potential energy of the composite structure, and issues of stability are assessed in this context. Three non-dimensional parameters that characterize the response of the ...


On The Behavior Of A Class Of Patched Plates During Cooling, Anette M. Karlsson, W. J. Bottega May 2000

On The Behavior Of A Class Of Patched Plates During Cooling, Anette M. Karlsson, W. J. Bottega

Mechanical Engineering Faculty Publications

The behavior of patched beam-plates during uniform cooling is considered. A non-linear formulation is adopted and the problems of interest are solved analytically yielding exact results within the context of the mathematical model employed. Three non-dimensional parameters corresponding to (i) a loading parameter, (ii) a critical temperature and (iii) a critical membrane force, are seen to characterize the response of the composite structure. Stability is considered and critical behavior includes bifurcation and asymptotic buckling, non-trivial “groundstates”, and demarcation and transition in deflection direction. Extensive numerical simulations based on analytical solutions are performed. Results are presented for various loading and support ...


The Influence Of Foot Positioning On Ankle Sprains, I. C. Wright, R. R. Neptune, Antonie J. Van Den Bogert, B. M. Nigg May 2000

The Influence Of Foot Positioning On Ankle Sprains, I. C. Wright, R. R. Neptune, Antonie J. Van Den Bogert, B. M. Nigg

Mechanical Engineering Faculty Publications

The goal of this study was to examine the influence of changes in foot positioning at touch-down on ankle sprain occurrence. Muscle model driven computer simulations of 10 subjects performing the landing phase of a side-shuffle movement were performed. The relative subtalar joint and talocural joint angles at touchdown were varied, and each subject-specific simulation was exposed to a set of perturbed floor conditions. The touchdown subtalar joint angle was not found to have a considerable influence on sprain occurrence, while increased touchdown plantar flexion caused increased ankle sprain occurrences. Increased touchdown plantar flexion may be the mechanism which causes ...


Quantification Of In Vivo Acl Elongation During Dynamic Joint Movements: A New Methodology, Scott G. Mclean, Antonie J. Van Den Bogert Apr 2000

Quantification Of In Vivo Acl Elongation During Dynamic Joint Movements: A New Methodology, Scott G. Mclean, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Anterior cruciate ligament (ACL) injuries are common in movement tasks incorporating sudden changes in velocity, such as sidtestepping. Current techniques adopted to quantify ACL strain are invasive as well as limited to slow, quasi-static move- ments. This paper presents a method for non-invasive measurement of ACL elongation during dynamic movement tasks, validation of the method, and demonstrates its applicability to the analysis of sidestep movements


Structure-Enhanced Yield Stress Of Magnetorheological Fluids, X. Tang, X. Zhang, R. Tao, Yiming Rong Mar 2000

Structure-Enhanced Yield Stress Of Magnetorheological Fluids, X. Tang, X. Zhang, R. Tao, Yiming Rong

Mechanical Engineering Faculty Publications

The yield stress of magnetorheological (MR) fluids depends on the induced solid structure. Since thick columns have a yield stress much higher than a single-chain structure, we improve the yield stress of MR fluids by changing the fluid microstructure. Immediately after a magnetic field is applied, we compress the MR fluid along the field direction. Scanning electron microscopy images show that particle chains are pushed together to form thick columns. The shear force measured after the compression shows that the structure-enhanced static yield stress can reach as high as 800 kPa under a moderate magnetic field, while the same MR ...


Movement Coupling At The Ankle During The Stance Phase Of Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg, Edgar Stüssi, Jachen Denoth Mar 2000

Movement Coupling At The Ankle During The Stance Phase Of Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg, Edgar Stüssi, Jachen Denoth

Mechanical Engineering Faculty Publications

The purpose of this study was to quantify movement coupling at the ankle during the stance phase of running using bone-mounted markers. Intracortical bone pins with reflective marker triads were inserted under standard local anaesthesia into the calcaneus and the tibia of five healthy male subjects. The three-dimensional rotations were determined using a joint coordinate system approach. Movement coupling was observed in all test subjects and occurred in phases with considerable individual differences. Between the shoe and the calcaneus coupling increased after midstance which suggested that the test shoes provided more coupling for inversion than for eversion. Movement coupling between ...


Structural Damage Detection Using Modal Norms, W. Gawronski, Jerzy T. Sawicki Jan 2000

Structural Damage Detection Using Modal Norms, W. Gawronski, Jerzy T. Sawicki

Mechanical Engineering Faculty Publications

No abstract provided.


Absolute Shape Measurements Using High-Resolution Optoelectronic Holography Methods, Cosme Furlong, Ryszard J. Pryputniewicz Jan 2000

Absolute Shape Measurements Using High-Resolution Optoelectronic Holography Methods, Cosme Furlong, Ryszard J. Pryputniewicz

Mechanical Engineering Faculty Publications

Characterization of surface shape and deformation is of primary importance in a number of testing and metrology applications related to the functionality, performance, and integrity of components. in this paper, a unique, compact, and versatile state-of-the-art fiber-optic-based optoelectronic holography (OEH) methodology is described. This description addresses apparatus and analysis algorithms, especially developed to perform measurements of both absolute surface shape and deformation. The OEH can be arranged in multiple configurations, which include the three-camera, three-illumination, and in-plane speckle correlation setups. With the OEH apparatus and analysis algorithms, absolute shape measurements can be made, using present setup, with a spatial resolution ...


New Test Methodology For Static And Dynamic Shape Measurements Of Microelectromechanical Systems, Gordon C. Brown, Ryszard J. Pryputniewicz Jan 2000

New Test Methodology For Static And Dynamic Shape Measurements Of Microelectromechanical Systems, Gordon C. Brown, Ryszard J. Pryputniewicz

Mechanical Engineering Faculty Publications

Current trends in the miniaturization of structures require the use of smaller and smaller components. Development of these microcomponents and, in turn, of mechanical microstructures/microsystems requires, in addition to the integrated use of advanced design, analysis, and fabrication methodologies, state-of-the-art test and measurement methodologies. We-have developed one such methodology, optoelectronic laser interferometric microscope (OLIM) methodology, with capabilities for rapid characterization of microelectromechanical systems (MEMSs); MEMSs are a unique class of mechanisms created using integrated circuit (IC) fabrication processes. Microgears and microengines, smaller than a gnat's eye, are groups of MEMSs created by such a process. MEMSs offer challenging ...


Effects Of Foot Orthoses On Skeletal Motion During Running, A. Stacoff, C. Reinschmidt, B. M. Nigg, Antonie J. Van Den Bogert, A. Lundberg, J. Denoth, E. Stüssi Jan 2000

Effects Of Foot Orthoses On Skeletal Motion During Running, A. Stacoff, C. Reinschmidt, B. M. Nigg, Antonie J. Van Den Bogert, A. Lundberg, J. Denoth, E. Stüssi

Mechanical Engineering Faculty Publications

Objective. To quantify the effects of medial foot orthoses on skeletal movements of the calcaneus and tibia during the stance phase in running.

Design. Kinematic effects of medial foot orthoses (anterior, posterior, no support) were tested using skeletal (and shoe) markers at the calcaneus and tibia.

Background. Previous studies using shoe and skin markers concluded that medially placed orthoses control/reduce foot eversion and tibial rotation. However, it is currently unknown if such orthoses also affect skeletal motion at the lower extremities.

Methods. Intracortical Hofman pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and ...