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Full-Text Articles in Mechanical Engineering

Redesign Of Parts And Simulation Of Flexible Assembly Cell For Safety Water Shower Assembly, Balraj Y. Gardilla Dec 1991

Redesign Of Parts And Simulation Of Flexible Assembly Cell For Safety Water Shower Assembly, Balraj Y. Gardilla

Theses

A Design for Assembly (DSA) method is used to analyze the safety water shower assembly and to redesign the components with emphasis on meeting the criteria of allowing for flexible Assembly Cell (FAS). An Expert System is developed to select the right Assembly using VP-Expert. This thesis contrasts the old and new safety water shower assembly designs and describes the design of a final Flexible Assembly Cell. A PUMA 550 robot was investigated for use in the cell design. The flexible Assembly cell is simulated on silicon graphics using the IGRIP software. The economics of each part presentation method is ...


Tardiness Heuristic For Scheduling Flexible Manufacturing Systems, Ali S. Kiran, Sema E. Alptekin, A. Celal Kaplan Jul 1991

Tardiness Heuristic For Scheduling Flexible Manufacturing Systems, Ali S. Kiran, Sema E. Alptekin, A. Celal Kaplan

Industrial and Manufacturing Engineering

This paper evaluates the tardiness performance of a sampling-based adaptive heuristic in a dynamic manufacturing environment. A test bed, following a real world manufacturing system, has been developed. The proposed algorithm has been implemented in this simulated environment. After fine tuning the algorithm, it has been tested in various shop conditions. The results of these simulation studies are summarized.


Size Reduction Of Polymeric Particulates By Jet Milling, Cheng Hua May 1991

Size Reduction Of Polymeric Particulates By Jet Milling, Cheng Hua

Theses

A basic theory for the size reduction operation by jet milling has been developed.

Typical samples of feedstock have been analyzed using screen analysis to determine the initial distribution of polymeric particulate sizes prior to jet milling.

A statistical theory .was developed using probabilities to represent the likelihood that specific size reductions would occur. These probabilities include the effects of various equipment.

The theory was then used to predict the distribution of polymeric particulate sizes after jet milling. The agreement between the predictions and actual results was within 5 %.

Encouraged by the successful work of the simulation of the process ...


Design For Manufacturability, Kocherlakota Sreedhar May 1991

Design For Manufacturability, Kocherlakota Sreedhar

Theses

Design for Manufacturability represents a new awareness of the importance of design as the first manufacturing step. It recognizes that a company cannot meet all its objectives with isolated design and manufacturing operations. The Design for Manufacturability approach embodies certain underlying imperatives that help maintain communication between all components of the Manufacturing and Design system and permit flexibility to adopt and to modify design during each stage of the product realization. Design for Manufacturability cannot be bought or sold and it should be implemented by management. Complete support of management to the implementation is very important to the success of ...


Development Of A Classification And Coding System For Computer-Aided Process Planning, Shilpan K. Patel May 1991

Development Of A Classification And Coding System For Computer-Aided Process Planning, Shilpan K. Patel

Theses

The chore of this work was to develop a Group Technology Classification Code which can represent the full gamut of simple, rotational parts. The automated coding plan is developed to alleviate the endeavor of the process planner to plan the tasks related to the manufacturing of a specific part. The 15 digits were devised from the Japanese KK-3 Classification and Coding system. The KK-3 System contains 21 digits. Our aim is to minimize the code length, and concurrently to eliminate the redundancies. As a result, a 15 digit G.T. Code is created. The proposed plan also generates the operation ...


Petri Net Modeling And Analysis Of An Fms Cell, Paresh A. Patel May 1991

Petri Net Modeling And Analysis Of An Fms Cell, Paresh A. Patel

Theses

Petri nets have evolved into a powerful tool for the modeling, analysis and design of asynchronous, concurrent systems. This thesis presents the modeling and analysis of a flexible manufacturing system (FMS) cell using Petri nets. In order to improve the productivity of such systems, the building of mathematical models is a crucial step.

In this thesis, the theory and application of Petri nets are presented with emphasis on their application to the modeling and analysis of practical automated manufacturing systems. The theory of Petri nets includes their basic notation and properties. In order to illustrate how a Petri net with ...


Design For Assembly : Re-Design Of An Electrical Switch For The Ease Of Automatic Assembly, Achyuta Reddy Pannala May 1991

Design For Assembly : Re-Design Of An Electrical Switch For The Ease Of Automatic Assembly, Achyuta Reddy Pannala

Theses

A design for assembly (DFA) method is used to analyze the existing design of parts of an electrical switch, and to reduce and re-design them, for the ease of automatic assembly. The procedure for the selection of suitable and economical assembly method is presented based on the Boothroyd & Dewhurst methods. Analysis of the initial design for manual assembly and the re-design for automatic assembly are presented. An algorithmic approach for simplified generation of all mechanical assembly sequences and selecting the good assembly sequences is presented with graphical representations. A work station needed for the automatic assembly is developed, which incorporates ...


Design For Manufacturability : Re-Design Of Pencil Sharpener For The Ease Of Assembly, Amit R. Rathod May 1991

Design For Manufacturability : Re-Design Of Pencil Sharpener For The Ease Of Assembly, Amit R. Rathod

Theses

A Design For Manufacturability (DFM) approach is used to analyze the existing design of a pencil sharpener, and to reduce and re-design the parts of pencil sharpener for the ease of assembly. The procedure for the selection of a suitable and economical assembly method is based on the Boothroyd and Dewhurst methods. Analysis of the initial design for manual assembly and re-design for automatic as well as manual assembly is presented. An algorithmic approach for simplified generation of all mechanical assembly sequences and selection of the assembly sequences is presented using De Fazio and Whitney approach.


Implementation Of Automated Assembly, Kang H. Kong May 1991

Implementation Of Automated Assembly, Kang H. Kong

Theses

Research has shown that about 60 - 80% wealth producing activities is related to manufacturing in major industrial countries.

Increased competition in industry has resulted in a greater emphasis on using automation to improve productivity and quality and also to reduce cost.

Most of the manufacturing works such as machining, painting, storage, retrieval, inspection and transportation have changed to automation successfully, except assembly. Manual assembly is predominant over automatic assembly techniques due to inherent assembly problem and the fact that the assembly machines lack the innate intelligence of human operator and lack sufficient flexibility to changeover when product designs and market ...


The Changing Role Of The Automotive Supplier, Samuel Arthur Schwall Jan 1991

The Changing Role Of The Automotive Supplier, Samuel Arthur Schwall

Theses and Dissertations

No abstract provided.


Development Of Theory Of Constraint-Based Framework For Determining Process Batch, Transfer Batch And Buffer Size In Shop Floor, Tajinder P.S. Vohra Jan 1991

Development Of Theory Of Constraint-Based Framework For Determining Process Batch, Transfer Batch And Buffer Size In Shop Floor, Tajinder P.S. Vohra

Theses and Dissertations

No abstract provided.


The Effect Of Equipment Bandwidth And Center Frequency Changes On Ultrasonic Inspection Reliability: Are Model Results Too Conservative? (A), R. L. Hockey, E. R. Green, A. A. Diaz Jan 1991

The Effect Of Equipment Bandwidth And Center Frequency Changes On Ultrasonic Inspection Reliability: Are Model Results Too Conservative? (A), R. L. Hockey, E. R. Green, A. A. Diaz

Review of Progress in Quantitative Nondestructive Evaluation

Reliable detection and sizing of material defects, which have been found in nuclear reactor piping and pressure vessels, has been shown [1,2] to be greatly affected by changing components of ultrasonic inservice inspection (UT/ISI) systems. The work reported here, in conjunction with our previous work [3–5], focuses on: providing a more rigorous analysis of equipment interaction and establishing a technical basis for current standards [6] for equipment operating tolerances which, before this work, were based on engineering judgement.


Interface Characterization By True Guided Modes, Peter B. Nagy, Laszlo Adler Jan 1991

Interface Characterization By True Guided Modes, Peter B. Nagy, Laszlo Adler

Review of Progress in Quantitative Nondestructive Evaluation

Guided acoustic waves along interfaces are especially sensitive to specific properties associated with boundary conditions and bond quality since their energy is effectively confined to the region of interest. On the other hand, this inherent advantage turns out to be a significant drawback for generation and detection of such guided waves. There are two basic types of propagating interface modes, which are shown schematically in Figure 1. First, there are leaky modes with higher phase velocity than at least one of the bulk velocities in the surrounding media. These modes “leak” their energy into one or more phase-matching bulk modes ...


The Reflection Of Ultrasound From Interface Layers In Adhesive Joints, Tom Pialucha, Peter Cawley Jan 1991

The Reflection Of Ultrasound From Interface Layers In Adhesive Joints, Tom Pialucha, Peter Cawley

Review of Progress in Quantitative Nondestructive Evaluation

The detection of a weak adhesive/adherend interface in an adhesive joint is one of the major current challenges in NDE; the lack of a satisfactory non destructive test for this region is retarding the exploitation of the advantages of adhesive bonding in safety critical areas. It is the interface layer which is affected by the common problem of slight contamination due to, for example, grease on the adherend surfaces prior to bonding. The interface is particularly important in aluminium-aluminium joints in which an inappropriate interface structure can cause greatly enhanced susceptibility to environmental attack [1]. Inspection of the interface ...


Ultrasonic Reflectivity Determination Of Interfacial Properties In Adhesive Joints Of Aluminum Alloys, W. Wang, B. Li, S. I. Rokhlin Jan 1991

Ultrasonic Reflectivity Determination Of Interfacial Properties In Adhesive Joints Of Aluminum Alloys, W. Wang, B. Li, S. I. Rokhlin

Review of Progress in Quantitative Nondestructive Evaluation

In studies of ultrasonic measurements of interfacial properties, it has previously been proposed [1] that an ultrasonic wave that produces shear stress on the interphase is sensitive to interphase properties. This may be achieved by utilization of interface waves [1,2] or guided waves in the bonded plates [3–5]. Another possibility is the use of obliquely incident ultrasonic waves for interphase evaluation, analyzing signals in the time or frequency domains [6–8].


Characterization Of Glued Bonds Using Ultrasonic Reflected Beam, A. Jung, Ph. Guy, A. Nayfeh, G. Quentin, J. C. Le Flour Jan 1991

Characterization Of Glued Bonds Using Ultrasonic Reflected Beam, A. Jung, Ph. Guy, A. Nayfeh, G. Quentin, J. C. Le Flour

Review of Progress in Quantitative Nondestructive Evaluation

Adhesive bonds of laminates of metal and polymer have been extensively studied using ultrasonic techniques. The strength of the bond is of primary importance and many studies have been aimed at deducing this property from ultrasonic measurements. The quality of adhesively joined structures is mainly determined by two types of factors: i) the cohesive strength of the glue ii) the adhesive strength of the metal-glue interface. To address the last type, several ultrasonic techniques using mainly plate and interface waves have been recently considered [1–4]. Their main advantage, compared to longitudinal or shear waves, is that they are very ...


Sonic Inspection Of Bonds In Viscoelastic Composites, A. F. Emery Jan 1991

Sonic Inspection Of Bonds In Viscoelastic Composites, A. F. Emery

Review of Progress in Quantitative Nondestructive Evaluation

Vibration isolation is frequently accomplished by placing rubber pads between a structure and its foundation. In typical industrial situations, the weight of the structure can be used to keep the pads in place and to ensure contact at the interface. However, when dampers are used for small electronic components, they are frequently glued to the component and to the support. The total unit then consists of the component, a glue interface, the rubber damper, a second glue interface, and the foundation. If the interfaces fail, compressive waves can usually be transmitted, but tensile stress waves encounter the separated layer which ...


Impedance Profiling For Bond Strength Evaluation, Nadir Saffari, David T. Green Jan 1991

Impedance Profiling For Bond Strength Evaluation, Nadir Saffari, David T. Green

Review of Progress in Quantitative Nondestructive Evaluation

Measurement of the strength of adhesive bonds in multi- layered structures is of increasing importance. Ultrasonic NDE methods do not directly determine the strength of a bond but indicate characteristics of a bond which may be related to bond strength through empirical relationships. One such bond characteristic is its acoustic impedance. Impedance profiling methods have long been studied in the field of geophysics and medical ultrasonics [1,2]. In this paper the development of an inversion algorithm based on the so called Goupillaud equal travel-time method is described [3], with the aim of applying it to the NDE of adhesive ...


Application Of Lamb Waves For Evaluation Of Lap-Shear Adhesive Joints, S. I. Rokhlin Jan 1991

Application Of Lamb Waves For Evaluation Of Lap-Shear Adhesive Joints, S. I. Rokhlin

Review of Progress in Quantitative Nondestructive Evaluation

Methods for nondestructive evaluation of adhesive joints have been extensively discussed in the literature because of the technological importance of the problem and the extreme difficulty of evaluation of interphasial properties [1]. Several methods have been proposed for adhesive joint interphase evaluation: ultilization of interphase [2,3] or guided [4–8] waves in the bonded plates or use of obliquely incident ultrasonic waves analyzing signals in the time or frequency domains [9–14]. Most of the above studies (except [5]) have evaluated the adhesive bond in bonded areas away from the sample edges. Even when the configuration of the experimental ...


An Ultrasonic Resonance Method To Determine The Acoustic Velocity Of Thin Adhesive Layers, E. C. Johnson, S. J. Sherman Jan 1991

An Ultrasonic Resonance Method To Determine The Acoustic Velocity Of Thin Adhesive Layers, E. C. Johnson, S. J. Sherman

Review of Progress in Quantitative Nondestructive Evaluation

The development of this ultrasonic method for determining the modulus of thin adhesive layers was motivated by the recent development of a nonintrusive ultrasonic Liquid Level Sensor (LLS) which meets military specifications for space launch [1,2]. The sensor is designed to signal when the surface of the fuel in a liquid propellant tank has receded to the level of the sensor during flight. As depicted in Fig. 1, the sensor is bonded to the outer tank wall with Versilok 202 (V202) adhesive [3]. To detect the fuel level, the sensor is stimulated to propagate an ultrasonic pulse into the ...


Numerical Comparison Of Experimentally Measured Ultrasound Through A Multilayered Specimen, John M. Sullivan Jr., Reinhold Ludwig, Yiping Geng, Vinod K. Nair Jan 1991

Numerical Comparison Of Experimentally Measured Ultrasound Through A Multilayered Specimen, John M. Sullivan Jr., Reinhold Ludwig, Yiping Geng, Vinod K. Nair

Review of Progress in Quantitative Nondestructive Evaluation

The integrity of bonded structures is of paramount importance in the safe and reliable operation of aircraft equipment. Fuselages, helicopter rotor blades and nose cones are multilayered composite structures bonded together. The operational readiness and security of these units depend to a large extent on the integrity of the interfacial bonds. Adhesive and cohesive strength studies do not appear promising because failure is really dominated by defects and not by some average physical properties of the adhesive and the interface [1].


Wave Scattering By An Inclusion Having Imperfect Interfaces With The Matrix, Jianmin Qu Jan 1991

Wave Scattering By An Inclusion Having Imperfect Interfaces With The Matrix, Jianmin Qu

Review of Progress in Quantitative Nondestructive Evaluation

Ultrasonic waves have been used in recent years to detect defects and damages in fiber-reinforced composite materials (see [1] for relevant references). A priori knowledge of how sound wave propagates through the composite medium is essential for using ultrasonic techniques in nondestructive evaluation. In the past, the problern of scattering by inclusions, such as fibers, has been studied extensively [2]–[3]. Most of the studies in the literature assume that the inclusions are perfectly boned to the matrix. However, defects are likely to exist along the fiber—matrix interfaces. As more interfacial defects are initiated, damages are developed within a ...


Analysis Of Bond Quality By Resonant Ultrasound, William M. Visscher, Alburt Migliori, Raymond D. Dixon Jan 1991

Analysis Of Bond Quality By Resonant Ultrasound, William M. Visscher, Alburt Migliori, Raymond D. Dixon

Review of Progress in Quantitative Nondestructive Evaluation

Analysis of the response of small samples of materials to mechanical excitations at ultrasonic frequencies (resonant ultrasound spectroscopy, or RUS) can yield much information about the sample, including its geometry, density (densities, if composite), and elastic constants. (1–5) In this paper, we sketch the experimental technique, the method by which the data can be analyzed, and extend the analysis to samples which comprise two different materials bonded together. In the latter case the technique can give information about the composition of the sample and bond integrity (i.e. whether or not displacements and stresses are continuous across the interface ...


Non-Destructive Evaluation In Manufacturing Using Spectroscopic Ellipsometry, John A. Woollam, Paul G. Snyder Jan 1991

Non-Destructive Evaluation In Manufacturing Using Spectroscopic Ellipsometry, John A. Woollam, Paul G. Snyder

Review of Progress in Quantitative Nondestructive Evaluation

The manufacture of optical coatings, computer disks, as well as advanced electronic multilayered devices and circuit structures requires high precision in the measurement and control of thicknesses and interfacial and surface roughnesses. Variable angle spectroscopic ellipsometry (VASE) is non-destructive and monolayer sensitive. VASE uses polarized light, and the technique can be applied in nearly any ambient, including air, vacuum, or corrosive environment. Applications to coated window glass, space protective coatings, semiconductor device, as well as sputtered media computer disk manufacturing are discussed. At the present time these NDE measurements are mainly ex situ, but in situ (during deposition) applications are ...


Eddy-Current Technique For Sub-Surface Temperature Measurement In A Cast Steel Strand, Guy Wiliams Jan 1991

Eddy-Current Technique For Sub-Surface Temperature Measurement In A Cast Steel Strand, Guy Wiliams

Review of Progress in Quantitative Nondestructive Evaluation

Temperature measurement is critical to the understanding and control of the solidification process in continuous steel casting. Many of the casting variables (for example, state, hot strength and ductility, microstructure) are strongly temperature dependant. A knowledge of temperature will also be required for energy management, particularly if further hot processing of the cast steel is to be performed. Although inferences can be drawn from mathematical modeling studies, direct measurement is required to validate these models, or to improve their accuracy, particularly if the models are used for process control. This paper describes work carried out at BHP MRL in the ...


Cross Section Measurement Of Long Cylindrical Products Without Contact Using Long Cylindrical Coils, B. De Halleux, B. Limburg De Stimm, P. Dumont, R. Van De Wyngaert Jan 1991

Cross Section Measurement Of Long Cylindrical Products Without Contact Using Long Cylindrical Coils, B. De Halleux, B. Limburg De Stimm, P. Dumont, R. Van De Wyngaert

Review of Progress in Quantitative Nondestructive Evaluation

The impedance Z of a solenoid with a conducting piece near it when capacity effects are neglected is Z = R + jωL with (1) R=Re−NωφosinϕIo (2) L=NωφocosϕIo where Re is the resistance of the wire of the coil, N is the number of single turns of the coil, Φo is the amplitude of the mean magnetic flux crossing the coil, Io is the amplitude of the current I circulating in the coil, ω is the pulsation of the current and ϕ is the phase of the flux relative to the current.


Real-Time Radiographic Investigation Of Weld Pool Depression, A. C. Guu, S. I. Rokhlin Jan 1991

Real-Time Radiographic Investigation Of Weld Pool Depression, A. C. Guu, S. I. Rokhlin

Review of Progress in Quantitative Nondestructive Evaluation

Real-time radiography has been utilized by us previously as a vision system in remote arc welding process monitoring [1]. Direct information on weld penetration extracted from real-time radiographic images of the solidified weld was used in feedback to adjust the welding conditions to maintain weld quality [2]. The disadvantage of this method is the time (and space) delay in extracting information on weld penetration which leads to the appearance of small weld areas with lack of penetration. In subsequent work weld penetration was controlled by the use of radiographic information on weld pool depression to eliminate the time delay thus ...


Process Monitoring Techniques Using Acoustic Waves, Sanjay Bhardwaj, B. T. Khuri-Yakub Jan 1991

Process Monitoring Techniques Using Acoustic Waves, Sanjay Bhardwaj, B. T. Khuri-Yakub

Review of Progress in Quantitative Nondestructive Evaluation

Process monitoring and control of semiconductor fabrication parameters, like film thickness, are important issues, limited at the present time by a lack of adequate sensors. In this paper, we outline the limitations of current film thickness technology and propose two new methods for nondestructive film thickness process monitoring: acoustic time domain reflectometry (TDR) and acoustic reflection coefficient phase measurements. Theoretical calculations and experimental measurements of different metal films are used to demonstrate the viability of these novel techniques.


Nuclear Power Plant Costs As A Function Of Nde Reliability, Michael J. Avioli Jr., Soung-Nan Liu Jan 1991

Nuclear Power Plant Costs As A Function Of Nde Reliability, Michael J. Avioli Jr., Soung-Nan Liu

Review of Progress in Quantitative Nondestructive Evaluation

The economic efficiency and safety of any power plant depends on the proper functioning of its component systems. The functioning of such systems (e.g., piping) is evaluated through performance of periodic nondestructive examinations (NDE). The results of these examinations determine actions the power plant owner must take regarding inspected components. If a component is found malfunctioning or containing a defect, the owner may decide to repair or replace the component. If the results of NDE indicates that the component is functioning as it should or is defect-free, he would most certainly take no action but to record such a ...


Manufacture Of Reference Defects For Nde Through Hot Isostatic Pressing, A. N. Sinclair, M. Graf, V. Dasilva, M. D. C. Moles, M. Doleby, S. Kramer, A. L. Allen Jan 1991

Manufacture Of Reference Defects For Nde Through Hot Isostatic Pressing, A. N. Sinclair, M. Graf, V. Dasilva, M. D. C. Moles, M. Doleby, S. Kramer, A. L. Allen

Review of Progress in Quantitative Nondestructive Evaluation

Nondestructive Evaluation techniques such as eddy current or ultrasonics do not give a direct visual indication of the key characteristics of a flaw. Some form of signal interpretation is required in order to determine flaw type, size, and shape. One tool that is frequently employed in the field is the “reference defect”; in the case of ultrasonic testing, reference defects typically consist of notches and flat-bottom or side-drilled holes in a calibration block. Not only are these artificial sound reflectors used to aid in the interpretation of flaw signals, but they may also be used to check that the NDE ...