Effect of Pavement Responses on Fatigue Cracking and Cement-Treated Reflective Cracking Failure Mechanisms

2021 ◽  
Vol 147 (4) ◽  
pp. 04021056
Author(s):  
Nirmal Dhakal ◽  
Mostafa Elseifi ◽  
Imad L. Al-Qadi ◽  
Tyson Rupnow
Keyword(s):  
Failure Mechanisms ◽  
Fatigue Cracking ◽  
Reflective Cracking

Understanding Sources of Variability of Overlay Test Procedure

2015 ◽  
Vol 2507 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Victor M. Garcia ◽  
Alejandro Miramontes
Keyword(s):  
Test Procedure ◽  
Fatigue Cracking ◽  
Laboratory Evaluation ◽  
Reflective Cracking ◽  
Climatic Effects ◽  
Test Protocol ◽  
Cracking Resistance ◽  
Number Of Cycles ◽  
Key Steps ◽  
Cycles To Failure

“Fatigue cracking” is defined as the accumulation of reflective cracking on hot-mix asphalt (HMA) layers under the repeated application of vehicular loads combined with climatic effects. Several highway agencies have either implemented or considered implementing the overlay tester (OT) to evaluate the fatigue cracking resistance of HMA specimens as a function of the number of cycles that the specimen may resist during the test until a reflective crack appears and propagates. The repeatability of the number of cycles to failure measured with the OT is considered as one of the main challenges in reliably evaluating the fatigue cracking resistance of asphalt mixtures. The objective of this paper is to discuss some of the sources and causes of variability of the parameters measured with the OT. Some of the possible causes of inconsistency in the results include the amount of torque applied to attach OT specimens, the amount of glue required for each OT specimen, the curing time of the glue, and the elapsed time between preparation and testing. For a better delineation of the uncertainties associated with the preparation process of HMA specimens and the mechanism of the OT equipment, a thorough study and practical laboratory evaluation of key steps involved in the overlay test protocol were performed on several synthetic and HMA specimens. Through the investigation of the important inconsistencies in the future guidelines, the variability and repeatability of the results from the OT on the number of cycles to failure may be improved.

scholarly journals Classification of Surface Pavement Cracks as Top-down, Bottom-up, and Cement-Treated Reflective Cracking Based on Deep Learning Methods

2021 ◽  
Author(s):  
Nirmal Dhakal ◽  
Mostafa A. Elseifi ◽  
Zia U. Zihan ◽  
Zhongjie Zhang ◽  
Christophe N. Fillastre ◽  
...  
Keyword(s):  
Neural Network ◽  
Deep Learning ◽  
Asphalt Concrete ◽  
Fatigue Cracking ◽  
Ann Model ◽  
Reflective Cracking ◽  
Top Down ◽  
Bottom Up ◽  
Concrete Layer ◽  
Artificial Neural Network Ann

The treatment and repair strategies of reflective and fatigue cracking that initiate at the pavement surface (i.e. top-down cracking) and at the bottom of the asphalt concrete layer (i.e. bottom-up cracking) are noticeably different. However, pavement engineers are facing difficulties in identifying these cracks in the field as they usually appear in visually identical patterns. The objective of this study was to develop Artificial Neural Network (ANN) and Convolutional Neural Network (CNN) applications to differentiate and classify top-down, bottom-up, and cement-treated reflective cracking in in-service pavements using deep-learning models. The developed CNN model achieved an accuracy of 93.8% in the testing and 91% in the validation phases and the ANN model showed an overall accuracy of 92%. The ANN classification tool was developed based on variables related to pavement and crack characteristics including age, Average Daily Traffic , thickness of Asphalt Concrete layer, type of base, crack orientation and location.

Small Bore Pipe Branch Connections Fatigue

2011 ◽  
Author(s):  
Jacques Economou ◽  
Yannick Thebault ◽  
Pierre-Emmanuel Costes
Keyword(s):  
Crack Initiation ◽  
Failure Mechanisms ◽  
Fatigue Cracking ◽  
The Other ◽  
Vibration Measurements ◽  
Nominal Diameter ◽  
Empirical Approaches ◽  
Service Inspection

Socket welds are used extensively for small bore pipe branch connections (up to a two-inch nominal diameter). For more than 15 years, numerous failures due to fatigue cracking occured in French NPPs (EDF operates 58 PWRs), mainly on safeguard systems as regards nuclear island safety-related systems. Such failures have significant impacts, on costs, due to repairs or In-Service-Inspections and sometimes, on plants availability. Destructive examination of cracked small bore pipe branch connections have led to a better understanding of failure mechanisms and have allowed to predict crack initiation locations depending on specific features such as main and small bore pipes thicknesses. Modifications implemented, based on empirical approaches, have turned out to be much or less efficient, depending on nuclear units. A three-stage methodology was devised in the early 2000’s and applied on the 8 most important safety-related systems. Based namely on vibration measurements, this methodology has allowed to identify sensitive small bore pipe branch connections, define a relevant In-Service Inspection program, determine vibrations origins and possible solutions. New modifications are currently underway on the 2 most affected systems. So far, they have shown to be effective. Solutions for the other systems should be decided at the end of 2011 and implemented on the whole French nuclear fleet.

Quantification of Pavement Damage Caused by Dual and Wide-Base Tires

2005 ◽  
Vol 1940 (1) ◽  
pp. 125-135 ◽  
Author(s):  
Mostafa A. Elseifi ◽  
Imad L. Al-Qadi ◽  
Pyeong J. Yoo ◽  
Ibrahim Janajreh
Keyword(s):  
Failure Mechanisms ◽  
Fatigue Cracking ◽  
Field Testing ◽  
Experimental Program ◽  
Tire Pressure ◽  
Load Carrying ◽  
Two Generations ◽  
Pavement Damage ◽  
New Generation ◽  
Truck Weight

A study conducted in 2001 on the heavily instrumented Virginia Smart Road measured pavement responses to a new generation of single wide-base tire (445/50R22.5) and to dual tires (275/80R22.5). The new single wide-base tire has a wider tread and a greater load-carrying capacity than conventional wide-base tires. The potential fatigue damage resulting from different tire configurations was evaluated. After successful field testing, a finite element (FE) parametric study was conducted to investigate different failure mechanisms that were not evaluated in the field. In this study, dual tires and two new generations of wide-base tires (445/50R22.5 and 455/55R22.5) were evaluated. The main difference between the two generations of wide-base tires is that the 455/55R22.5 is wider than the 445/50R22.5; hence, it further reduces the contact stress at the pavement surface under the same nominal tire pressure. In the developed FE models, geometry and dimensions were selected to simulate accurately the axle configurations typically used in North America; actual tire tread sizes and applicable contact pressure for each tread were considered; laboratory-measured pavement material properties were incorporated; and models were calibrated and properly validated against stress and strain measurements obtained from the experimental program. Four failure mechanisms were considered: fatigue cracking, primary rutting, secondary rutting, and top-down cracking. Results indicated that the new generations of wide-base tire would cause the same or relatively greater pavement damage than conventional dual tires. Because overall truck weight is reduced by approximately 450 kg when wide-base tires are used, it is reasonable to implement the load limits currently applied to the dual-tire assembly on the 455/55R22.5 wide-base tire.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

Real-time cryo-deformation of polypropylene and impact-modified polypropylene in the transmission electron microscope

1993 ◽  
Vol 51 ◽  
pp. 892-893
Author(s):  
Robert C. Cieslinski ◽  
H. Craig Silvis ◽  
Daniel J. Murray
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Failure Mechanisms ◽  
Brittle Transition ◽  
Molded Part ◽  
Transmission Electron ◽  
Solvent Cast ◽  
The Impact ◽  
Annealed Copper ◽  
Dynamic Plane

An understanding of the mechanical behavior polymers in the ductile-brittle transition region will result in materials with improved properties. A technique has been developed that allows the realtime observation of dynamic plane stress failure mechanisms in the transmission electron microscope. With the addition of a cryo-tensile stage, this technique has been extented to -173°C, allowing the observation of deformation during the ductile-brittle transition.The technique makes use of an annealed copper cartridge in which a thin section of bulk polymer specimen is bonded and plastically deformed in tension in the TEM using a screw-driven tensile stage. In contrast to previous deformation studies on solvent-cast films, this technique can examine the frozen-in morphology of a molded part.The deformation behavior of polypropylene and polypropylene impact modified with EPDM (ethylene-propylene diene modified) and PE (polyethylene) rubbers were investigated as function of temperature and the molecular weight of the impact modifier.

Identification of the characteristic length scale for fatigue cracking in fretting contacts

1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-159-Pr8-166 ◽  
Author(s):  
S. Fouvry ◽  
Ph. Kapsa ◽  
F. Sidoroff ◽  
L. Vincent
Keyword(s):  
Characteristic Length ◽  
Fatigue Cracking ◽  
Length Scale ◽  
Characteristic Length Scale
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