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2013

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Articles 1 - 30 of 1285

Full-Text Articles in Mechanical Engineering

Numerical Modeling Of Infrared Thermography Techniques Via Ansys, Hayder Abdulnabi Thajeel Dec 2013

Numerical Modeling Of Infrared Thermography Techniques Via Ansys, Hayder Abdulnabi Thajeel

Masters Theses

"Several inspection techniques have been developed over years. Recently, infrared thermography (IRT) technology has become a widely accepted as a nondestructive inspection (NDI) technique for different fields and various applications as well. Infrared thermography stands as one of the most an attractive and a successful NDI technique that has ability to detect the object's surface/subsurface defects remotely based on observing and measuring the surface's emitted infrared heat radiation by using an infrared camera. The finite element modeling FEM ANSYS was successfully used for the modelling of several IRT techniques; such as Pulsed Thermography (PT) and Lock-in Thermography ...


Computational Optimization Methods For Modeling The Effect Of Muscle Forces On Bone Strength Adaptation, Catherine Siena Florio Dec 2013

Computational Optimization Methods For Modeling The Effect Of Muscle Forces On Bone Strength Adaptation, Catherine Siena Florio

Dissertations

An improved understanding of the mechanical influences that alter the strength of a bone can aid in the refinement of the wide array of currently available techniques to counteract the losses of bone strength that occur due to age or disuse both on Earth and in Space. To address this need, computational modeling methods to quantitatively analyze and compare the effects of mechanical factors on the strength of a targeted bone within a multibone, multimuscle system are developed and implemented in this work. Through a more detailed representation of the system in which the bone acts and the creation of ...


Method For Focused Electric-Field Imprinting For Micron And Sub-Micron Patterns On Wavy Or Planar Surfaces, Ambar K. Mitra, Ashraf F. Bastawros, Abhijit Chandra, Charles A. Lemaire Dec 2013

Method For Focused Electric-Field Imprinting For Micron And Sub-Micron Patterns On Wavy Or Planar Surfaces, Ambar K. Mitra, Ashraf F. Bastawros, Abhijit Chandra, Charles A. Lemaire

Aerospace Engineering Patents

Focused Electric Field Imprinting (FEFI) provides a focused electric field to guide an unplating operation and/or a plating operation to form very fine-pitched metal patterns on a substrate. The process is a variation of the electrochemical unplating process, wherein the process is modified for imprinting range of patterns of around 2000 microns to 20 microns or less in width, and from about 0.1 microns or less to 10 microns or more in depth. Some embodiments curve a proton-exchange membrane whose shape is varied using suction on a backing fluid through a support mask. Other embodiments use a curved ...


کارگاه اصول نگارش مقالات علمی 1, Dr Alireza Zolfaghari Dec 2013

کارگاه اصول نگارش مقالات علمی 1, Dr Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.


Pre-Impact Lower Extremity Posture And Brake Pedal Force Predict Foot And Ankle Forces During An Automobile Collision, Elizabeth C. Hardin, Anne Su, Antonie J. Van Den Bogert Dec 2013

Pre-Impact Lower Extremity Posture And Brake Pedal Force Predict Foot And Ankle Forces During An Automobile Collision, Elizabeth C. Hardin, Anne Su, Antonie J. Van Den Bogert

Antonie J. van den Bogert

Background: The purpose of this study was to determine how a driver’s foot and ankle forces during a frontal vehicle collision depend on initial lower extremity posture and brake pedal force. Method of Approach: A 2D musculoskeletal model with seven segments and six right-side muscle groups was used. A simulation of a three-second braking task found 3647 sets of muscle activation levels that resulted in stable braking postures with realistic pedal force. These activation patterns were then used in impact simulations where vehicle deceleration was applied and driver movements and foot and ankle forces were simulated. Peak rearfoot ground ...


Concurrent Simulation Of Neuromuscular Control And Tissue Deformation Is Possible By Adaptive Surrogate Modeling, Jason P. Halloran, Ahmet Erdemir, Antonie J. Van Den Bogert Dec 2013

Concurrent Simulation Of Neuromuscular Control And Tissue Deformation Is Possible By Adaptive Surrogate Modeling, Jason P. Halloran, Ahmet Erdemir, Antonie J. Van Den Bogert

Antonie J. van den Bogert

No abstract provided.


Comment On "Quadriceps Protects The Anterior Cruciate Ligament", Antonie J. Van Den Bogert Dec 2013

Comment On "Quadriceps Protects The Anterior Cruciate Ligament", Antonie J. Van Den Bogert

Antonie J. van den Bogert

No abstract provided.


Tibiocalcaneal Kinematics Of Barefoot Versus Shod Running, Alex Stacoff, Benno M. Nigg, Christoph Reinschmidt, Antonie J. Van Den Bogert, Arne Lundberg Dec 2013

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

Antonie J. van den Bogert

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 ...


Effect Of Gender And Defensive Opponent On The Biomechanics Of Sidestep Cutting, Scott G. Mclean, Susanne W. Lipfert, Antonie J. Van Den Bogert Dec 2013

Effect Of Gender And Defensive Opponent On The Biomechanics Of Sidestep Cutting, Scott G. Mclean, Susanne W. Lipfert, Antonie J. Van Den Bogert

Antonie J. van den Bogert

Purpose: Anterior cruciate ligament (ACL) injuries often occur in women during cutting maneuvers to evade a defensive player. Gender differences in knee kinematics have been observed, but it is not known to what extent these are linked to abnormal neuromuscular control elsewhere in the kinetic chain. Responses to defense players, which may be gender-dependent, have not been included in previous studies. This study determined the effects of gender and defense player on entire lower extremity biomechanics during sidestepping. Methods: Eight male and eight female subjects performed sidestep cuts with and without a static defensive opponent while 3D motion and ground ...


Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner Dec 2013

Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner

Antonie J. van den Bogert

We previously reported that the probability of an older adult recovering from a forward trip and using a “lowering” strategy increases with decreased walking velocity and faster response time. To determine the within-subject interaction of these variables we asked three questions: (1) Is the body orientation at the time that the recovery foot is lowered to the ground (“tilt angle”) critical for successful recovery? (2) Can a simple inverted pendulum model, using subject-specific walking velocity and response time as input variables, predict this body orientation, and thus success of recovery? (3) Is slower walking velocity or faster response time more ...


Evaluation Of A Two Dimensional Analysis Method As A Screening And Evaluation Tool For Anterior Cruciate Ligament Injury, Scott G. Mclean, K. Walker, K. R. Ford, G. D. Myer, T. E. Hewett, Antonie J. Van Den Bogert Dec 2013

Evaluation Of A Two Dimensional Analysis Method As A Screening And Evaluation Tool For Anterior Cruciate Ligament Injury, Scott G. Mclean, K. Walker, K. R. Ford, G. D. Myer, T. E. Hewett, Antonie J. Van Den Bogert

Antonie J. van den Bogert

Background: Increased knee valgus predicts the risk of anterior cruciate ligament (ACL) injury, particularly in women. Reducing injury rates thus relies on detecting and continually evaluating people with relatively large valgus motions. Objectives: To examine the potential of a two dimensional (2D) video analysis method for screening for excessive valgus. Methods: Ten female and 10 male National Collegiate Athletic Association basketball players had three dimensional (3D) knee valgus and two dimensional (2D) frontal plane knee angle quantified during side step, side jump, and shuttle run tasks. 3D valgus was quantified from external marker coordinates using standard techniques, and 2D data ...


The Influence Of Foot Positioning On Ankle Sprains, I. C. Wright, R. R. Neptune, Antonie J. Van Den Bogert, B. M. Nigg Dec 2013

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

Antonie J. van den Bogert

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 ...


Mechanical Properties Of The Tendinous Equine Interosseus Muscle Are Affected By In Vivo Transducer Implantation, M. O. Jansen, H. C. Schamhardt, Antonie J. Van Den Bogert, W. Hartman Dec 2013

Mechanical Properties Of The Tendinous Equine Interosseus Muscle Are Affected By In Vivo Transducer Implantation, M. O. Jansen, H. C. Schamhardt, Antonie J. Van Den Bogert, W. Hartman

Antonie J. van den Bogert

Liquid metal strain gauges (LMSGs) were implanted in the tendinous interosseous muscle, also called suspensory ligament (SL), in the forelimbs of 6 ponies in order to quantify in vivo strains and forces. Kinematics and ground reaction forces were recorded simultaneously with LMSG signals at the walk and the trot prior to implantation, and 3 and 4 days thereafter. The ponies were euthanised and tensile and failure tests were performed on the instrumented tendons and on the tendons of the contra lateral limb, which were instrumented post mortem. The origo–insertional (OI) strain of the SL was computed from pre- and ...


Contributions Of Proximal And Distal Moments To Axial Tibial Rotation During Walking And Running, T. L. Bellchamber, Antonie J. Van Den Bogert Dec 2013

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

Antonie J. van den Bogert

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 ...


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 Dec 2013

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

Antonie J. van den Bogert

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 ...


Horses Damp The Spring In Their Step, Alan M. Wilson, M. Polly Mcguigan, Anne Su, Antonie J. Van Den Bogert Dec 2013

Horses Damp The Spring In Their Step, Alan M. Wilson, M. Polly Mcguigan, Anne Su, Antonie J. Van Den Bogert

Antonie J. van den Bogert

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle–tendon units1, 2.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints3, 4. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle5. Despite ...


Acl Injuries: Do We Know The Mechanisms?, Antonie J. Van Den Bogert, Scott G. Mclean Dec 2013

Acl Injuries: Do We Know The Mechanisms?, Antonie J. Van Den Bogert, Scott G. Mclean

Antonie J. van den Bogert

Injuries of the anterior cruciate ligament (ACL) remain a frequent occurrence in many sports activities. Recent research has identified risk factors, and prevention strategies are being developed based on these findings. There is, however, still a limited understanding of the actual injury mechanisms. In this presentation we will review the current knowledge on ACL injury mechanisms, and identify needs and opportunities for further research.


Biomechanical Measures Of Neuromuscular Control And Valgus Loading Of The Knee Predict Anterior Cruciate Ligament Injury Risk In Female Athletes, Timothy E. Hewett, Gregory D. Myer, Kevin R. Ford, Robert S. Heidt Jr., Angelo J. Colosimo, Scott G. Mclean, Antonie J. Van Den Bogert, Mark V. Paterno, Paul Succop Dec 2013

Biomechanical Measures Of Neuromuscular Control And Valgus Loading Of The Knee Predict Anterior Cruciate Ligament Injury Risk In Female Athletes, Timothy E. Hewett, Gregory D. Myer, Kevin R. Ford, Robert S. Heidt Jr., Angelo J. Colosimo, Scott G. Mclean, Antonie J. Van Den Bogert, Mark V. Paterno, Paul Succop

Antonie J. van den Bogert

Background: Female athletes participating in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than do male athletes. Hypothesis: Prescreened female athletes with subsequent anterior cruciate ligament injury will demonstrate decreased neuromuscular control and increased valgus joint loading, predicting anterior cruciate ligament injury risk. Study Design: Cohort study; Level of evidence, 2. Methods: There were 205 female athletes in the high-risk sports of soccer, basketball, and volleyball prospectively measured for neuromuscular control using 3-dimensional kinematics (joint angles) and joint loads using kinetics (joint moments) during a jump-landing task. Analysis of variance as well as linear ...


Computer-Assisted Gait Analysis In Equine Orthopaedic Practice: The Case For Inverse Dynamic Analysis, Antonie J. Van Den Bogert Dec 2013

Computer-Assisted Gait Analysis In Equine Orthopaedic Practice: The Case For Inverse Dynamic Analysis, Antonie J. Van Den Bogert

Antonie J. van den Bogert

No abstract provided.


Quantification Of In Vivo Acl Elongation During Dynamic Joint Movements: A New Methodology, Scott G. Mclean, Antonie J. Van Den Bogert Dec 2013

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

Antonie J. van den Bogert

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


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 Dec 2013

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

Antonie J. van den Bogert

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 ...


Foot And Ankle Forces During An Automobile Collision: The Influence Of Muscles, Elizabeth C. Hardin, Anne Su, Antonie J. Van Den Bogert Dec 2013

Foot And Ankle Forces During An Automobile Collision: The Influence Of Muscles, Elizabeth C. Hardin, Anne Su, Antonie J. Van Den Bogert

Antonie J. van den Bogert

Muscles have a potentially important effect on lower extremity injuries during an automobile collision. Computational modeling can be a powerful tool to predict these effects and develop protective interventions. Our purpose was to determine how muscles influence peak foot and ankle forces during an automobile collision. A 2-D bilateral musculoskeletal model was constructed with seven segments. Six muscle groups were included in the right lower extremity, each represented by a Hill muscle model. Vehicle deceleration data were applied as input and the resulting movements were simulated. Three models were evaluated: no muscles (NM), minimal muscle activation at a brake pedal ...


Development And Validation Of A 3-D Model To Predict Knee Joint Loading During Dynamic Movement, Scott G. Mclean, Anne Su, Antonie J. Van Den Bogert Dec 2013

Development And Validation Of A 3-D Model To Predict Knee Joint Loading During Dynamic Movement, Scott G. Mclean, Anne Su, Antonie J. Van Den Bogert

Antonie J. van den Bogert

The purpose of this study was to develop a subject-specific 3-D model of the lowerextremity to predict neuromuscular control effects on 3-D knee joint loading during movements that can potentially cause injury to the anterior cruciate ligament (ACL) in the knee. The simulation consisted of a forward dynamic 3-D musculoskeletal model of the lower extremity, scaled to represent a specific subject. Inputs of the model were the initial position and velocity of the skeletal elements, and the muscle stimulation patterns. Outputs of the model were movement and ground reaction forces, as well as resultant 3-D forces and moments acting across ...


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 Dec 2013

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

Antonie J. van den Bogert

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 ...


Sagittal Plane Biomechanics Cannot Injure The Acl During Sidestep Cutting, Scott G. Mclean, Xuemei Huang, Anne Su, Antonie J. Van Den Bogert Dec 2013

Sagittal Plane Biomechanics Cannot Injure The Acl During Sidestep Cutting, Scott G. Mclean, Xuemei Huang, Anne Su, Antonie J. Van Den Bogert

Antonie J. van den Bogert

Background. Knee joint sagittal plane forces are a proposed mechanism of anterior cruciate ligament injury during sport movements such as sidestep cutting. Ligament force magnitudes for these movements however, remain unknown. The need to examine injury-causing events suggests elucidation via model-based investigations is possible. Using this approach, the current study determined whether sagittal plane knee loading during sidestep cutting could in isolation injure the anterior cruciate ligament. Methods. Experiments were performed on subject-specific forward dynamic musculoskeletal models, generated from data obtained from 10 male and 10 female athletes. Models were optimized to simulate subject-specific cutting movements. Random perturbations (n=5000 ...


Promoting Electrocatalytic Activity Of A Composite Sofc Cathode La0.8Sr0.2Mno3+Δ/Ce0.8Gd0.2O2-Δ With Molten Carbonates, Yunhui Gong, Xue Li, Lingling Zhang, Whitney Tharp, Changyong Qin, Kevin Huang Dec 2013

Promoting Electrocatalytic Activity Of A Composite Sofc Cathode La0.8Sr0.2Mno3+Δ/Ce0.8Gd0.2O2-Δ With Molten Carbonates, Yunhui Gong, Xue Li, Lingling Zhang, Whitney Tharp, Changyong Qin, Kevin Huang

Faculty Publications

The effect of molten carbonates (MCs) on polarization resistance (RP), a direct measure of oxygen reduction reaction (ORR) activity, of a composite La0.8Sr0.2MnO3+δ/Ce0.8Gd0.2O2-δ (LSM/GDC) solid oxide fuel cell (SOFC) cathode has been systematically investigated in this study over a temperature range of 550–650°C and partial pressure of oxygen (pO2) span of 10−3 ∼ 1 atm. It is shown that the LSM/GDC cathode, either in the pristine or MC-modified states, can be generally modeled by two consecutive parallel circuits ...


Experimental Investigation Of Mist Film Cooling And Feasibility Study Of Mist Transport In Gas Turbines, Reda M. Ragab Dec 2013

Experimental Investigation Of Mist Film Cooling And Feasibility Study Of Mist Transport In Gas Turbines, Reda M. Ragab

University of New Orleans Theses and Dissertations

In the modern advanced gas turbines, the turbine inlet temperature may exceed 1500°C as a requirement to increase power output and thermal efficiency. Therefore, it is imperative that the blades and vanes are cooled so they can withstand these extreme temperatures. Film cooling is a cooling technique widely used in high-performance gas turbines. However, the film cooling effectiveness has almost reached plateau, resulting in a bottleneck for continuous improvement of gas turbines' efficiency.

In this study, an innovative cooling scheme, mist film cooling is investigated through experiments. A small amount of tiny water droplets with an average diameter about ...


A Study On The Integration Of A Novel Absorption Chiller Into A Microscale Combined Cooling, Heating, And Power (Micro-Cchp) System, Scott J. Richard Dec 2013

A Study On The Integration Of A Novel Absorption Chiller Into A Microscale Combined Cooling, Heating, And Power (Micro-Cchp) System, Scott J. Richard

University of New Orleans Theses and Dissertations

This study explores the application of micro-CCHP systems that utilize a 30 kW gas microturbine and an absorption chiller. Engineering Equation Solver (EES) is used to model a novel single-effect and double-effect water-lithium bromide absorption chiller that integrates the heat recovery unit and cooling tower of a conventional CCHP system into the chiller’s design, reducing the cost and footprint of the system. The results of the EES model are used to perform heat and material balances for the micro-CCHP systems employing the novel integrated chillers, and energy budgets for these systems are developed. While the thermal performance of existing ...


A Numerical Study Of High Temperature And High Velocity Gaseous Hydrogen Flow In A Cooling Channel Of A Ntr Core, Sajan B. Singh Dec 2013

A Numerical Study Of High Temperature And High Velocity Gaseous Hydrogen Flow In A Cooling Channel Of A Ntr Core, Sajan B. Singh

University of New Orleans Theses and Dissertations

Two mathematical models (a one and a three-dimensional) were adopted to study, numerically, the thermal hydrodynamic behavior of flow inside a single cooling channel of a Nuclear Thermal Rocket (NTR) engine. The first model assumes the flow in the cooling channel to be one-dimensional, unsteady, compressible, turbulent, and subsonic. The working fluid (GH2) is assumed to be compressible. The governing equations of the 1-D model are discretized using a second order accurate finite difference scheme. Also, a commercial CFD code is used to study the same problem. Numerical experiments, using both codes, simulated the flow and heat transfer in ...


Buckling, Postbuckling And Imperfection Sensitivity Analysis Of Different Type Of Cylindrical Shells By Hui's Postbuckling Method, Hailan Xu Dec 2013

Buckling, Postbuckling And Imperfection Sensitivity Analysis Of Different Type Of Cylindrical Shells By Hui's Postbuckling Method, Hailan Xu

University of New Orleans Theses and Dissertations

Hui and Chen (1986) were the first to show that the well-known Koiter’s General Theory of Elastic Stability of 1945 can be significantly improved by evaluating the postbuckling b coefficient at the actual applied load, rather than at the classical buckling load. Such improvement method was demonstrated to be (1) very simple to apply with no tedious algebra, (2) significant reduction in imperfection sensitivity and (3) although it is still asymptotically valid, there exists a significant extension of the range of validity involving larger imperfection amplitudes. Strictly speaking, Koiter’s theory of 1945 is valid only for vanishingly small ...