Engineering Commons^™

Hybrid Transient-Parametric Method And System To Distinguish And Analyze Sources Of Acoustic Emission For Nondestructive Inspection And Structural, Health Monitoring, Yuris Dzenis

Department of Mechanical and Materials Engineering: Faculty Publications

A nondestructive evaluation (NDE) technique for inspecting or health monitoring of Structures and/or Specimens by analyzing acoustic emission (AE) signals emitted by the Structures and/or specimens. The method and System ana lyzes acoustic emission (AE) signals emitted by structures and/or Specimens. AE Signals emitted by the Structures and/or Specimens are parametrically filtered as a function of parametric filters corresponding to characteristic waveforms of transient AE classes of predefined AE signals. In para metric analysis, the filtering may be pre- or post-recording. In transient AE analysis, the filtering may be prior to transient recording of the transient signals.

Crash Attenuation System, John D. Reid, John R. Rohde, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A crash attenuation system having an impact head, and energy absorption mechanism. The energy absorbing mechanism has a mandrel for rupturing thin-walled tubes in a controlled rupture to absorb impact forces from a colliding vehicle. A frame may be used to mount the system to a truck, trailer, guardrail, median barrier end treatment, or a crash cushion. Stress concentrators may be incorporated into the tubes and the mandrels to selectively control rupturing and energy dissipation.

Oct 2001, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Software Program Storage Space Needed 16 new members

Fabrication Of 2- And 3-Dimensional Nanostructures, Hong Jiang, Camelia N. Borca, Bo Xu, Brian W. Robertson

Department of Mechanical and Materials Engineering: Faculty Publications

Amongst tools for fabricating periodic and aperiodic nanostructures and nanodevices, electron beam-induced organometallic chemical vapor deposition (E-OMCVD) offers a highly flexible and controllable one-step deposition process. E-OMCVD enables maskless fabrication of nanoscale research and custom structures that have least dimensions near or below 10 nm–a scale at which other methods prove difficult or costly. Using the focused electron beam in a modified HB501 field-emission scanning transmission electron microscope (STEM), pads and wires with uniform thickness and well-defined shapes have been defined and deposited. Although conditions for fabricating the smallest deposits have not yet been optimized, the edge acuity (sharpness) of …

Delamination Resistant Composites Prepared By Small Diameter Fiber Reinforcement At Ply Interfaces, Youris A. Dzenis, Darrell H. Reneker

Department of Mechanical and Materials Engineering: Faculty Publications

A fiber reinforced composite material comprising a resin matrix and primary reinforcement fibers and further comprising secondary, smaller diameter, reinforcement fibers at one or more ply interfaces, or portion thereof, provides improved interlaminar toughness, strength, and delamination resistance and without substantial increase in weight. In one embodiment, the small fibers are attached to one side of a conventional prepreg prior to lamination. The small fibers are flexible and are expected to conform to the shape and distribution of the primary reinforcing fibers at the interface.

Jul 2001, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

UN Foundation Tractor Raffle Oliver Tractor Repair

Energy Absorbing Breakaway Steel Guardrail Post, John R. Rohde, John D. Reid, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

An improved breakaway steel guardrail post for use in dissipation of impact energy upon impact of the post having an upper post member and a lower post member, a connecting joint, and a mechanism connected to the upper and lower post members for controlling the energy dissipation of the guardrail post about the connecting joint at a predetermined rate. A first embodiment utilizes a cable restraint lopped through openings in he guardrail posts. Other embodiments included straps and fasteners disigned to distort or fail at predetermined rates or strengths and combinations thereof.

Controlled Buckling Breakaway Cable Terminal, John D. Reid, John R. Rohde, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A crash attenuation apparatus for use with a guardrail system having rail posts and rail elements. An impact head has a buffer nose section and a rail post breaking beam system. The post breaking beam system has upper and lower breaking beams attached to the head. A guide tube is attached to the side of the head. A strut member extends from a first attachment point on the rail element to a second point downstream. Upon impact by a vehicle, the head breaks the first rail post, before impacting the strut and buckling the rail element downstream.

Apr 2001, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

Camp Creek Swap Meet Public Relations Get Fordson Running

Analysis Of Microdamage Evolution Histories In Composites, Yuris A. Dzenis, Jie Qian

Department of Engineering Mechanics: Faculty Publications

Evolution of microdamage in advanced composites was experimentally studied in this paper. A new method of acoustic emission (AE) analysis of histories of different damage mechanisms was formulated based on a combination of transient AE classification and multiparameter filtering. The capabilities of the method were illustrated on examples of damage evolution in several graphite/epoxy composites. Three characteristic AE waveforms with different frequency spectra were identified based on the transient analysis. Regions occupied by these waveforms in the amplitude–rise time parametric space were identified for the [0]₈ and [90]₁₆ unidirectional composites. Multiparameter filtering was applied to extract evolution histories …

Effects Of Concentration And Temperature On The Coupled Heat And Mass Transport In Liquid Mixtures, Yaşar Demirel, Stanley I. Sandler

Papers in Thermal Mechanics

Using published experimental data on the thermal conductivity, mutual diffusivity, and heats of transport, the degree of coupling between heat and mass flows has been calculated for binary and ternary nonideal liquid mixtures. The binary mixtures consist of two types: the first is six systems of six-to-eight-carbon straight and branched chain alkanes in chloroform and in carbon tetrachloride; and the second is mixtures of carbon tetrachloride with benzene, toluene, 2-propanone, n-hexane, and 11-octane. The ternary mixture considered is toluene-chlorobenzene-bromobenzene. The published data are available at 35°C, 30°C, and 35°C and ambient pressure. Using the linear nonequilibi-ium thermodynainics (LNET) and the …

Rate Effects On Mode-I Delamination Toughness Of A Graphite/Epoxy Laminated Composite, Xiangfa Wu, Yuris A. Dzenis

Department of Engineering Mechanics: Faculty Publications

Mechanical properties of composite materials made of high modulus fibers and relatively low modulus polymeric matrix, such as graphite/epoxy laminated composites, are sensitive to loading rate and temperature. Generally, at fixed loading rate, when temperature increases, the fracture toughness of polymers also increases; however, it will decrease with the increase of loading rate at constant testing temperature. Rate effects on fracture toughness are of critical to understand the fracture transition from ductile to brittle of some polymers. However, there have been fewer studies of rate effects on delamination toughness of laminates compared to that of pure polymers. In the present …

Jan 2001, Tractor Museum

Lester F. Larsen Tractor Museum: Planning and Development Documents

New Personel Area rearrangement Missouri Valley Wrench Club

Conjugate Heat Transfer From A Two- Layer Substrate Model Of A Convectively Cooled Circuit Board, S. A. Harman, Kevin D. Cole

Department of Mechanical and Materials Engineering: Faculty Publications

This note presents the results of a study of a simple model of an air-cooled electronic device mounted on a circuit board. The model includes a flush-mounted heater to represent the electronic device, a two-layer substrate to represent the circuit board, and a steady shear flow to represent the cooling fluid.

Ortega provides a good review of the literature and a comprehensive introduction to conjugate methods applied to electronic cooling, emphasizing simple shear flows and single-layer substrates to illustrate basic principles. Ortega also describes two-layer effects by including infrared thermographs of a convectively cooled glass/epoxy circuit board with copper traces, …

Linear-Nonequilibrium Thermodynamics Theory For Coupled Heat And Mass Transport, Yaşar Demirel, Stanley I. Sandler

Yaşar Demirel Publications

Linear-nonequilibrium thermodynamics (LNET) has been used to express the entropy generation and dissipation functions representing the true forces and flows for heat and mass transport in a multicomponent fluid. These forces and flows are introduced into the phenomenological equations to formulate the coupling phenomenon between heat and mass flows. The degree of the coupling is also discussed. In the literature such coupling has been formulated incompletely and sometimes in a confusing manner. The reason for this is the lack of a proper combination of LNET theory with the phenomenological theory. The LNET theory involves identifying the conjugated flows and forces …

Task Specific Uncertainty In Coordinate Measurement, R. G. Wilhelm, R. Hocken, H. Schwenke

Department of Mechanical and Materials Engineering: Faculty Publications

Task specific uncertainty is the measurement uncertainty associated with the measurement of a specific feature using a specific measurement plan. This paper surveys techniques developed to model and estimate task specific uncertainty for coordinate measuring systems, primarily coordinate measuring machines using contacting probes. Sources of uncertainty are also reviewed.

On Modular Design Of Field Robotic Systems, Shane Farritor, Steven Dubowsky

Department of Mechanical and Materials Engineering: Faculty Publications

Robots are needed to perform important field tasks such as hazardous material clean-up, nuclear site inspection, and space exploration. Unfortunately their use is not widespread due to their long development times and high costs. To make them practical, a modular design approach is proposed. Prefabricated modules are rapidly assembled to give a low-cost system for a specific task. This paper described the modular design problem for field robots and the application of a hierarchical selection process to solve this problem. Theoretical analysis and an example case study are presented. The theoretical analysis of the modular design problem revealed the large …

Using A Rapid Prototyping Machine In The Integrated Kinematics, Dynamics, And Machine Design Lab, Wieslaw M. Szydlowski

Department of Mechanical and Materials Engineering: Faculty Publications

According to a recent trend, two different labs - the Machine Design lab, and Kinematics, and Dynamics lab are combined into one integrated lab. The time students spend on their projects is halved. To save the quality of undergraduate education, an ew methodology has to be developed. The paper explains the methodology developed by the author while teaching the integrated Kinematics, Dynamics, and Machine Design Lab (MECH 488) at the Mechanical Engineering Department of the University of Nebraska-Lincoln.

The objective of the aforementioned lab is to teach the students, who have no design experience, how to select proper tools (firom …

Nebraska Summary 354: Agco Dt200 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Summary 355: Agco Dt225 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1789: John Deere 9200 24 & 12 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Summary 388: Fendt 918 Vario Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1791: John Deere 9400t Also 9420t 24 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Nebraska Summary 391: Fendt 926 Vario Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …

Test 1796: Case Ih Stx 275/New Holland Tj 275 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1797: Case Ih Stx 325/New Holland Tj 325 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1790: 9300 T 24 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1796: Case Ih Stx 275/New Holland Tj 275 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1797: Case Ih Stx 325/New Holland Tj 325 Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

Test 1792: Massey Ferguson 2210 Diesel 15-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA

The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data.

EXPLANATION OF THE TEST PROCEDURES

Purpose

The purpose of …