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Articles 1 - 30 of 76
Full-Text Articles in Engineering
Experimental Validation Of Multistep Quantitative Crack Damage Assessment For Truss Structures By Finite Element Model Updating, Soon Lee, Gunjin Yun, Mohammad Rahimi, Shen Shang
Experimental Validation Of Multistep Quantitative Crack Damage Assessment For Truss Structures By Finite Element Model Updating, Soon Lee, Gunjin Yun, Mohammad Rahimi, Shen Shang
Gunjin Yun
In this paper, a multistep damage quantification method has been experimentally validated by quantifying crack damage of load-carrying members of truss structures based on experimental vibration records. Damage quantifications are still challenging tasks for difficulties in interpreting response signals measured from engineering structures. Open crack depth is parameterized as a damage variable. The open crack in Euler–Bernoulli beam element is modeled by introducing local flexibility coefficients to the uncracked beam element with joint rotational flexibility. Mode shapes and natural frequencies measured from experimental modal testing of a damaged laboratory-size truss bridge are used in the finite element model updating for …
The Fracture Behavior Of An Al–Mg–Si Alloy During Cyclic Fatigue, Diya Azzam, Craig Menzemer, Tirumalai Srivatsan
The Fracture Behavior Of An Al–Mg–Si Alloy During Cyclic Fatigue, Diya Azzam, Craig Menzemer, Tirumalai Srivatsan
Craig Menzemer
In this paper, is presented and discussed the cyclic fracture behavior of the Al–Mg–Si alloy 6063 that is a candidate used in luminaire light poles. The light poles were subject to fatigue deformation. Test sections were taken from the failed region of the light pole and carefully examined in a scanning electron microscope with the objective of rationalizing the macroscopic fracture mode and intrinsic micromechanisms governing fracture under cyclic loading. The fatigue fracture surface of the alloy revealed distinct regions of early microscopic crack growth, stable crack growth and unstable crack growth and overload. An array of fine striations was …
The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick
The Quasi-Static Deformation, Failure, And Fracture Behavior Of Titanium Alloy Gusset Plates Containing Bolt Holes, Therese Hurtuk, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan, Kannan Manigandan, T. Quick
Craig Menzemer
In this article, the influence of bolt holes, specifically their number and layout on strength, deformation, and final fracture behavior of titanium alloy gusset plates under the influence of an external load is presented and discussed. Several plates having differences in both the number and layout of the bolt holes were precision machined and then deformed under quasi-static loading. The specific influence of number of bolt holes and their layout on maximum load-carrying capability and even fracture load was determined. The conjoint influence of bolt number, bolt layout pattern, nature of loading, contribution from local stress concentration, and intrinsic microstructural …
A Study To Evaluate And Understand The Response Of Aluminum Alloy 2026 Subjected To Tensile Deformation, Daniel Lam, Craig Menzemer, Tirumalai Srivatsan
A Study To Evaluate And Understand The Response Of Aluminum Alloy 2026 Subjected To Tensile Deformation, Daniel Lam, Craig Menzemer, Tirumalai Srivatsan
Craig Menzemer
The strain concentration factors were determined for aluminum alloy 2026 in the T3511 temper using multi-hole structural coupon specimens. Samples of the alloy were evaluated for both the 6.25 mm (0.25 in.) thick and 10 mm (0.4 in.) thick specimens and having widths of 50 mm (2 in.) and 100 mm (4 in.), respectively. For the case of the specimens that were 50 mm in width the mechanical tests were conducted for both the open hole and filled hole conditions and the corresponding strain concentration value was determined. Threaded fasteners having collars were used for the case of the filled …
The Bolt Bearing Response And Tensile Deformation Capacity Of Plates Made From A Titanium Alloy, Nicholas Tinl, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan
The Bolt Bearing Response And Tensile Deformation Capacity Of Plates Made From A Titanium Alloy, Nicholas Tinl, Craig Menzemer, Anil Patnaik, Tirumalai Srivatsan
Craig Menzemer
In this article, the bearing capacity and elongation characteristics of bolt holes in a titanium alloy (i.e., Ti-6Al-4V) deformed in uniaxial tension is presented and discussed. The specific role played by bolt hole confinement on bearing capacity is highlighted. The nature of final fracture is examined and the intrinsic features present on the fracture surface are rationalized in concurrence with macroscopic mechanical response. The behavior of the candidate alloy (Ti-6Al-4V) is compared with conventionally preferred and chosen candidate materials steel and aluminum alloys. An empirical relationship suitable for purpose of structural design is proposed.
An Investigation And Understanding Of The Mechanical Response Of Palmyrah Timber, Hatim Sobier, Craig Menzemer, Tirumalai Srivatsan
An Investigation And Understanding Of The Mechanical Response Of Palmyrah Timber, Hatim Sobier, Craig Menzemer, Tirumalai Srivatsan
Craig Menzemer
The Palmyrah tree flourishes in tropical areas around South East Asia, and particularly in Sri Lanka. Palmyrah is an important economic resource for the region, and has found use in structural applications for both residential dwellings and commercial buildings. While there is a great deal of local field experience with Palmyrah, the mechanical properties have not been well characterized or understood. In an effort to assist engineers with the design and efficient use of the timber, a study was undertaken to evaluate the mechanical response of Palmyrah and develop estimates of design allowable properties. Properties evaluated include static bending strength, …
Understanding The Mechanical Response Of Built-Up Welded Beams Made From Commercially Pure Titanium And A Titanium Alloy, Anil Patnaik, Narendra Poondla, Craig Menzemer, Tirumalai Srivatsan
Understanding The Mechanical Response Of Built-Up Welded Beams Made From Commercially Pure Titanium And A Titanium Alloy, Anil Patnaik, Narendra Poondla, Craig Menzemer, Tirumalai Srivatsan
Craig Menzemer
During the last two decades, titanium has gradually grown in stature, strength and significance to take on the recognition of being a modern and high performance metal that is noticeably stronger and concurrently lighter than the most widely chosen and used steels in a spectrum of industrial applications. Technological innovations have necessitated reduction of part weight, cost and lead time, including concurrent enhancement of performance of structural parts and components made using titanium and its alloys. This has provided the impetus to develop economically viable structural design methodologies and specifications, while at the same time bringing forth innovative and economically …
A Study Of Fatigue And Fracture Response Of Cantilevered Luminaire Structures Made From Aluminum Alloy 6063, Craig Menzemer, Diya Azzam, Tirumalai Srivatsan
A Study Of Fatigue And Fracture Response Of Cantilevered Luminaire Structures Made From Aluminum Alloy 6063, Craig Menzemer, Diya Azzam, Tirumalai Srivatsan
Craig Menzemer
In the experimental results elegantly and exhaustively elaborated upon in this paper the local stresses, obtained from finite element analysis, was used to develop estimates of the stress intensity factor (SIF). In combination with crack growth data, the fatigue lives of both the through-plate and an integrally stiffened socket connection were estimated using software developed by the U.S. Air Force (and referred to as AFGROW). The fatigue life estimates correlated well with the test results provided the crack growth rate data was obtained under conditions of minimal closure at higher stress ratios (of the order R = 0.7). In an …
Isolating Corrosion Of Steel Plates Coupled With Titanium, Anil Patnaik, X. Shan, M. Adams, T. Srivatsan, Craig Menzemer, Joe Payer
Isolating Corrosion Of Steel Plates Coupled With Titanium, Anil Patnaik, X. Shan, M. Adams, T. Srivatsan, Craig Menzemer, Joe Payer
Craig Menzemer
Over twenty six percent of the bridges in the United States are structurally deficient or functionally obsolete. Corrosion of steel used in structures like bridges and buildings is a problem that has gained increased interest and focused concern. Steel is often the metal that is preferred for use in such applications due to a synergism of ease of availability, acceptable mechanical properties and cost effectiveness. Through the years, titanium has grown in strength, stature and significance to be recognized as an emerging high performance metal that is both stronger and lighter than steel. A distinctive property of titanium and its …
Mechanisms Governing Fatigue, Damage, And Fracture Of Commercially Pure Titanium For Viable Aerospace Applications, Udaykar Bathini, Tirumalai Srivatsan, Anil Patnaik, Craig Menzemer
Mechanisms Governing Fatigue, Damage, And Fracture Of Commercially Pure Titanium For Viable Aerospace Applications, Udaykar Bathini, Tirumalai Srivatsan, Anil Patnaik, Craig Menzemer
Craig Menzemer
In this paper, the cyclic stress amplitude controlled high-cycle fatigue properties and final fracture behavior of commercially pure titanium (Grade 2) are presented and discussed. The material characterization was developed and put forth for selection and use in a spectrum of applications spanning the industries of aerospace, defense, chemical, marine, and commercial products. Test specimens were prepared from the as-received plate stock of the material with the stress axis both parallel (longitudinal) and perpendicular (transverse) to the rolling direction of the plate. The test specimens were cyclically deformed at a constant load ratio of 0.1, at different values of maximum …
Infuence Of Welding And Heat Treatment On Microstructure, Properties And Fracture Behaviour Of A Wrought Aluminium Alloy, Eric Hilty, Craig Menzemer, Kannan Manigandan, Tirumalai Srivatsan
Infuence Of Welding And Heat Treatment On Microstructure, Properties And Fracture Behaviour Of A Wrought Aluminium Alloy, Eric Hilty, Craig Menzemer, Kannan Manigandan, Tirumalai Srivatsan
Craig Menzemer
Welding of aluminium alloy, belonging to the 6XXX series, exerts an adverse influence on its strength. The loss of strength immediately adjacent to the welds can have an influence on overall behaviour of the structure or component. In this study, the technique of gas metal arc welding was used. The filler material used was a silicon-containing aluminium alloy. Subsequent to welding, the alloy (6061-T4) was subjected to post-weld heat treatment (PWHT) at 185°C for 6 h. Both the as-welded and artificially aged extrusions of aluminium alloy 6061 were examined for both microstructural development and resultant influence on mechanical properties. Light …
The Bearing Strength And Fracture Behavior Of Bolted Connections In Two Aluminum Alloys, Nicholas Tinl, Craig Menzemer, Kannan Manigandan, Tirumalai Srivatsan
The Bearing Strength And Fracture Behavior Of Bolted Connections In Two Aluminum Alloys, Nicholas Tinl, Craig Menzemer, Kannan Manigandan, Tirumalai Srivatsan
Craig Menzemer
In this paper, the bearing capacity, taken as a combination of strength, elongation, and failure by fracture characteristics of bolt holes in two aluminum alloys, 5052-H32 and 6061-T6, that were deformed in uniaxial tension is presented and discussed. The specific role played by bolt hole confinement on the bearing capacity of each aluminum alloy is highlighted. An increase in the bearing ratio caused plastic deformation around the holes to gradually increase. For both the chosen aluminum alloys the average bearing ratio at the time of failure of the test sample was found to vary with end distance. The experimentally determined …
Closure To “Analysis And Design Method For Slope Stabilization Using A Row Of Drilled Shafts, Robert Liang, Arash Joorabchi, Lin Li
Closure To “Analysis And Design Method For Slope Stabilization Using A Row Of Drilled Shafts, Robert Liang, Arash Joorabchi, Lin Li
Robert Y. Liang
No abstract provided.
Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan
Extrinsic Influence Of Environment On The Corrosion Behaviour Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, Kannan Manigandan, Tirumalai Srivatsan
Robert Y. Liang
A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …
A Clustering Based Method To Evaluate Soil Corrosivity For Pipeline External Integrity Management, Ayako Yajima, Hui Wang, Robert Liang, Homero Castaneda
A Clustering Based Method To Evaluate Soil Corrosivity For Pipeline External Integrity Management, Ayako Yajima, Hui Wang, Robert Liang, Homero Castaneda
Robert Y. Liang
One important category of transportation infrastructure is underground pipelines. Corrosion of these buried pipeline systems may cause pipeline failures with the attendant hazards of property loss and fatalities. Therefore, developing the capability to estimate the soil corrosivity is important for designing and preserving materials and for risk assessment. The deterioration rate of metal is highly influenced by the physicochemical characteristics of a material and the environment of its surroundings. In this study, the field data obtained from the southeast region of Mexico was examined using various data mining techniques to determine the usefulness of these techniques for clustering soil corrosivity …
Bayesian Modeling Of External Corrosion In Underground Pipelines Based On The Integration Of Markov Chain Monte Carlo Techniques And Clustered Inspection Data, Hui Wang, Ayako Yajima, Robert Liang, Homero Castaneda
Bayesian Modeling Of External Corrosion In Underground Pipelines Based On The Integration Of Markov Chain Monte Carlo Techniques And Clustered Inspection Data, Hui Wang, Ayako Yajima, Robert Liang, Homero Castaneda
Robert Y. Liang
In this study, a model is developed to assess external corrosion in buried pipelines based on the unification of Bayesian inferential structure derived from Markov chain Monte Carlo techniques using clustered inspection data. This proposed stochastic model combines clustering algorithms that can ascertain the similarity of corrosion defects and Monte Carlo simulation that can give an accurate probability density function estimation of the corrosion rate. The metal loss rate is chosen as the indicator of corrosion damage propagation, obeying a generalized extreme value (GEV) distribution. Bayesian theory was employed to update the probability distribution of metal loss rate as well …
A Simplified Approach For Negative Skin Friction Calculation Of Special-Shaped Pile Considering Pile-Soil Interaction Under Surcharge, Gang-Qiang Kong, Hang Zhou, Han-Long Liu, Xuan-Ming Ding, Robert Liang
A Simplified Approach For Negative Skin Friction Calculation Of Special-Shaped Pile Considering Pile-Soil Interaction Under Surcharge, Gang-Qiang Kong, Hang Zhou, Han-Long Liu, Xuan-Ming Ding, Robert Liang
Robert Y. Liang
A simplified approach was proposed to analyze the negative skin friction calculation of special-shaped pile considering pile-soil interaction under surcharge. Based on the concentric cylinder shearing theory, considering the changes of pile shape (such as, taper angle and diameters of pile base, etc.), the load-transfer of special-shaped pile was built. The accuracy of the developed simplified approach was verified by numerical simulation model with the same condition. Then, the influence factors, such as, taper angles, the diameter of pile base, surcharge, and pile-soil interface parameters were analyzed and discussed. The results show that the developed simplified approach can calculate NSF …
Extrinsic Influence Of Environment On The Corrosion Behavior Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, K. Manigandan, Tirumalai Srivatsan
Extrinsic Influence Of Environment On The Corrosion Behavior Of Enamel-Coated Steel Dowel Bars, Srikanth Bajaj, Anil Patnaik, Joe Payer, Robert Liang, K. Manigandan, Tirumalai Srivatsan
Robert Y. Liang
A new type of enamel coated dowel bars for use as concrete pavements has been recently developed and implemented. A gradual deterioration of such bars can occur due to corrosion occurring at locations of the fine microscopic cracks and other defects in the coating. The results of a study aimed at evaluating and understanding the corrosion resistance of such dowel bars is presented and comparisons made with corresponding epoxy-coated dowel bars. Identical defects were introduced onto the surface of the dowel bars with the two types of coatings. The extrinsic influence of environment and resultant corrosion based on type, location …
Importance Sampling Based Algorithm For Efficient Reliability Analysis Of Axially Loaded Piles, Haijian Fan, Robert Liang
Importance Sampling Based Algorithm For Efficient Reliability Analysis Of Axially Loaded Piles, Haijian Fan, Robert Liang
Robert Y. Liang
In reliability analysis, the crude Monte Carlo method is known to be computationally demanding. To improve computational efficiency, this paper presents an importance sampling based algorithm that can be applied to conduct efficient reliability evaluation for axially loaded piles. The spatial variability of soil properties along the pile length is considered by random field modeling, in which a mean, a variance, and a correlation length are used to statistically characterize a random field. The local averaging subdivision technique is employed to generate random fields. In each realization, the random fields are used as inputs to the well-established load transfer method …
System Reliability Analysis For Anchor-Stabilised Slopes Considering Stochastic Corrosion Of Anchors, Lin Li, Robert Liang, Hanlong Liu
System Reliability Analysis For Anchor-Stabilised Slopes Considering Stochastic Corrosion Of Anchors, Lin Li, Robert Liang, Hanlong Liu
Robert Y. Liang
In this paper, a methodology using Monte Carlo simulation method was developed in conjunction with the modified limiting equilibrium method of slices. Additionally, the time-dependent deterioration of bond capacity of corroding soil anchors was developed in this methodology due to the attack of chlorides. Uncertainties of anchor-related variables and soil parameters were considered using pertinent statistical descriptors. Furthermore, the inherent stochastic nature of the corrosion and degradation process for the anchor/slope system was identified and incorporated in the simulation. A PC-based software, C-UASLOPE, has been coded to allow for handling of complex slope geometry, soil profile and groundwater conditions. An …
Compressive Sensing For Feedback Reduction In Mimo Broadcast Channels, Mohammed Eltayeb, Tareq Al-Naffour, Hamid Bahrami
Compressive Sensing For Feedback Reduction In Mimo Broadcast Channels, Mohammed Eltayeb, Tareq Al-Naffour, Hamid Bahrami
Hamid Bahrami
In multi-antenna broadcast networks, the base sta-tions (BSs) rely on the channel state information (CSI) of the users to perform user scheduling and downlink transmission. However, in networks with large number of users, obtaining CSI from all users is arduous, if not impossible, in practice. This paper proposes channel feedback reduction techniques based on the theory of compressive sensing (CS), which permits the BS to obtain CSI with acceptable recovery guarantees under substantially reduced feedback overhead. Additionally, assuming noisy CS measurements at the BS, inexpensive ways for improving post-CS detection are explored. The proposed techniques are shown to reduce the …
Condition Based Maintenance Optimization Of Wind Turbine System Using Degradation Prediction, Elham Pazouki, Hamid Bahrami, Seungdeog Choi
Condition Based Maintenance Optimization Of Wind Turbine System Using Degradation Prediction, Elham Pazouki, Hamid Bahrami, Seungdeog Choi
Hamid Bahrami
This paper proposes an optimal Condition Based Maintenance (CBM) policy for a multi-component system. Especially, multicomponent wind turbine has been analyzed to investigate cost relationship between maintenance and energy production schedule. Wind turbine consists of numerous mechanical and electrical components, and each of which shows independent stochastic deterioration process. The fundamental of proposed strategy is derived based on the statistically modeled aging and deterioration of each critical component in the wind turbine system to optimally schedule CBM task. Scheduling the CBM task is variably and iteratively performed through optimizing joint failure probability threshold and inspection/maintenance interval to minimize the total …
Non-Linear Interactions Of Acoustic Fields With Plates Under Harmonic Excitations, A. Nayfeh, S. Kelly
Non-Linear Interactions Of Acoustic Fields With Plates Under Harmonic Excitations, A. Nayfeh, S. Kelly
Dr. S. Graham Kelly
The method of renormalization is used to determine a uniformly valid expansion for the problem of non-linear interactions of acoustic fields with plates under harmonic excitations. The expansion obtained is in agreement with that obtained by Ginsberg, who used the method of strained co-ordinates to render the potential uniform and then used the method of renormalization to render the non-uniform pressure and velocity components calculated from the resulting potential uniform.
Stress Response Of A Rubber Block With Frictional Contact Under Axial Loading, J. Suh, S. Kelly
Stress Response Of A Rubber Block With Frictional Contact Under Axial Loading, J. Suh, S. Kelly
Dr. S. Graham Kelly
Rubber blocks (or springs) are structural components widely used in many applications. Design characteristics of a rubber block under axial loading are an apparent modulus (or compression modulus) and normal and shear stresses on contact surfaces. These are affected by a contact condition of the rubber block in contact with two rigid plates and the shape of the block. The problem of a rubber block bonded to two rigid plates has been solved using various approaches. In contrast, for a rubber block whose one surface is bonded to a rigid plate and the other surface in contact with a frictional …
Development Of Normal Mode Theory For Multi-Degree-Of-Freedom Systems Using An Energy Inner Product, S. Kelly
Development Of Normal Mode Theory For Multi-Degree-Of-Freedom Systems Using An Energy Inner Product, S. Kelly
Dr. S. Graham Kelly
No abstract provided.
Fundamentals Of Mechanical Vibrations, S. Kelly
Fundamentals Of Mechanical Vibrations, S. Kelly
Dr. S. Graham Kelly
This text is designed for undergraduate courses in vibrations taught in departments of mechanical engineering. It provides detailed explanations of fundamental aspects of vibrations such as the derivation of differential equations, covers physical interpretation of phenomena using energy methods, and includes chapters on vibration control and nonlinear vibrations. Detailed coverage of the equivalent systems method allows modelling of all one-degree-of-freedom linear systems by a mass-spring-dashpot system.
Non-Linear Propagation Of Directional Spherical Waves, S. Kelly, A. Nayfeh
Non-Linear Propagation Of Directional Spherical Waves, S. Kelly, A. Nayfeh
Dr. S. Graham Kelly
The method of renormalization is used to determine a uniformly valid expansion for the problem of non-linear waves produced in a fluid by spatially non-uniform simple harmonic motion of the surface of a sphere. The effect of dimensionless quantities upon the acoustic shock-formation distance is examined.
Non-Linear Propagation Of General Directional Spherical Waves, S. Kelly, A. Nayfeh
Non-Linear Propagation Of General Directional Spherical Waves, S. Kelly, A. Nayfeh
Dr. S. Graham Kelly
The method of renormalization is used to determine a uniformly valid expansion for the problem of non-linear waves produced in a fluid by the general harmonic pulsations of a sphere. For a uniform expansion, only the radial distance needs to be strained. The effect of dimensionless quantities upon the shock-formation distance is examined.
Mechanics Of Rubber Shear Springs, A. Gent, J. Suh, S. Kelly
Mechanics Of Rubber Shear Springs, A. Gent, J. Suh, S. Kelly
Dr. S. Graham Kelly
FEA calculations have been carried out for a model rubber shear spring, consisting of a block of a highly elastic material, bonded between two rigid parallel plates and sheared by displacing one of the plates parallel to the other in its own plane. The block was prevented from deforming in the perpendicular direction, and thus was deformed in plane strain. Stress distributions along the bond-line and the center-line are reported and compared with those expected from the theory of large elastic deformations. Unexpected tensile stresses were found to develop in the interior of the sheared block. They are attributed to …
Natural Frequency And Mode Shape Perturbations For Linear Multidegree Of Freedom Systems, S. Kelly
Natural Frequency And Mode Shape Perturbations For Linear Multidegree Of Freedom Systems, S. Kelly
Dr. S. Graham Kelly
No abstract provided.