Concept and Development of an Accelerated Repeated Rolling Wheel Load Simulator (ARROWS) for Fatigue Performance Characterization of Asphalt Mixture

Fatigue performance is one of the most important properties that affect the service life of asphalt mixture. Many fatigue test methods have been developed to evaluate the fatigue performance in the lab. Although these methods have contributed a lot to the fatigue performance evaluation and the development of fatigue related theory and model, their limitations should not be ignored. This paper starts by characterizing the stress state in asphalt pavement under a rolling wheel load. After that, a literature survey focusing on the experimental methods for fatigue performance evaluation is conducted. The working mechanism, applications, benefits, and limitations of each method are summarized. The literature survey results reveal that most of the lab test methods primarily focus on the fatigue performance of asphalt mixture on a material level without considering the effects of pavement structure. In addition, the stress state in the lab samples and the loading speed differ from those of asphalt mixture under rolling wheel tire load. To address these limitations, this paper proposes the concept of an innovative lab fatigue test device named Accelerated Repeated Rolling Wheel Load Simulator (ARROWS). The motivation, concept, and working mechanism of the ARROWS are introduced later in this paper. The ARROWS, which is under construction, is expected to be a feasible and effective method to simulate the repeated roll wheel load in the laboratory.

Microwave Interferometric System for GPR Positioning

Ground penetrating radar (GPR) systems are sensors that are able to acquire underground images by scanning the surface of the soil/pavement under investigation. Usually, a GPR system records its own position along the scan line, using a mechanical odometer, i.e., a rolling wheel in contact with the ground. This simple and cheap solution can be ineffective on uneven terrains. In this paper, a positioning system based on an interferometric radar is presented. This kind of radar is able to detect small displacements of the targets in its field of view. Such a capability was used to track the GPR position along a line. The system was validated with simulations and tested in a realistic experimental scenario.

Moving Wheel versus Impact Deflections and Their Use in Pavement Evaluation

Traffic speed deflection devices (TSDDs) have been developed since around 2000 to allow for safe and efficient structural evaluation of highway networks. One barrier to TSDD implementation is the inherent differences in deflections produced by moving truck loads and by falling weight deflectometer (FWD), the current deflection testing standard. To better understand the differences in data produced by the two devices, FHWA sponsored research into one particular TSDD, the rolling wheel deflectometer (RWD). The study utilized the finite layer program ViscoWave to model both FWD and RWD loads to demonstrate the effect of their inherent differences on pavement deflections and other simulated parameters. In addition, ViscoWave was used to generate theoretical FWD and RWD deflections for a diverse set of pavement structures and subgrade conditions. The resulting deflections were used to develop correlations between the two devices, which were validated with side-by-side FWD and RWD field tests performed on 23 sites. The research determined that the differences between FWD and RWD deflections vary depending on pavement factors and loading characteristics. The two devices produced similar deflections on thicker, stiffer, lower-deflection pavements, while the FWD produced relatively higher deflections on thinner, weaker, higher-deflection pavements. Therefore, use of common FWD data analysis programs will produce different results, such as layer moduli, for TSDD devices. Advanced analysis routines capable of modeling the TSDD’s moving load and loading configurations are needed.

Understanding Test Modalities of Tire Grip and Laboratory-Road Correlations with Modeling

The present study is meant to obtain tribological insight into the interface of a rolling rubber wheel on a counter-surface disk based on the work of the previous study Salehi et al. (Tribol Lett 68(1):37, 2020), in which a new test method was developed to rapidly predict tire grip in a laboratory environment. A Laboratory Abrasion Tester (LAT100) was used and exploited as a tribometer. This opened a new cost- and time-effective horizon for tire material development in a laboratory environment rather than having to test tread compounds by building full-scale tires. The method was validated by a comprehensive study for six different tire tread compositions, by correlating the laboratory data for solid rubber wheels as LAT100 specimens with real tire results in two test modalities: lateral (α) and longitudinal (κ) sweep tests on a dry road. It was demonstrated that the LAT100 can be exploited to simulate the $$\alpha$$ α -sweep tire tests, but not the $$\kappa$$ κ -sweep. The dynamics and physics of a rolling rubber wheel on a counter-surface disk of the LAT100 test step-up are investigated utilizing the renowned physical “brush model” in comparison to full-scale tire tests. The type of test modality leads to different friction mechanisms in the contact patch even at similar test conditions. This is substantiated by recognizing the two regions: stationary and non-stationary, in the contact area which results in different friction components and mechanisms. The behavior of the rolling wheel in lateral and longitudinal movements at the same test conditions is comparable if the contributions of the mentioned regions in the contact area are similar.

Collision Avoidance and Stability Study of a Self-Reconfigurable Drainage Robot

The inspection and maintenance of drains with varying heights necessitates a drain mapping robot with trained labour to maintain community hygiene and prevent the spread of diseases. For adapting to level changes and navigating in the narrow confined environments of drains, we developed a self-configurable hybrid robot, named Tarantula-II. The platform is a quadruped robot with hybrid locomotion and the ability to reconfigure to achieve variable height and width. It has four legs, and each leg is made of linear actuators and modular rolling wheel mechanisms with bi-directional movement. The platform has a fuzzy logic system for collision avoidance of the side wall in the drain environment. During level shifting, the platform achieves stability by using the pitch angle as the feedback from the inertial measuring unit (IMU) mounted on the platform. This feedback helps to adjust the accurate height of the platform. In this paper, we describe the detailed mechanical design and system architecture, kinematic models, control architecture, and stability of the platform. We deployed the platform both in a lab setting and in a real-time drain environment to demonstrate the wall collision avoidance, stability, and level shifting capabilities of the platform.

A consensus approach toward the standardization of spinal stiffness measurement using a loaded rolling wheel device: results of a Delphi study

Background Spinal stiffness assessment has the potential to become an important clinical measure. Various spinal stiffness-testing devices are available to help researchers objectively evaluate the spine and patient complaints. One of these is VerteTrack, a device capable of measuring posteroanterior displacement values over an entire spinal region. This study aimed to develop a best-practice protocol for evaluating spinal stiffness in human participants using VerteTrack. Methods Twenty-five individuals with research experience in measuring spinal stiffness, or who were trained in spinal stiffness measurement using the VerteTrack device, were invited to participate in this 3-Round Delphi study. Answers to open-ended questions in Round 1 were thematically analyzed and translated into statements about VerteTrack operation for spinal stiffness measurements. Participants then rated their level of agreement with these statements using a 5-point Likert scale in Rounds 2 and 3. A descriptive statistical analysis was performed. Consensus was achieved when at least 70% of the participants either strongly agreed, agreed, (or strongly disagreed, disagreed) to include a statement in the final protocol. Results Twenty participants completed Round 1 (80%). All these participants completed Rounds 2 and 3. In total, the pre-defined consensus threshold was reached for 67.2% (123/183) of statements after three rounds of surveys. From this, a best-practice protocol was created. Conclusions Using a Delphi approach, a consensus-based protocol for measuring spinal stiffness using the VerteTrack was developed. This standard protocol will help to improve the accuracy, efficiency, and safety of spinal stiffness measurements, facilitate the training of new operators, increase consistency of these measurements in multicenter studies, and provide the synergy and potential for data comparison between spine studies internationally. Although specific to VerteTrack, the resulting standard protocol could be modified for use with other devices designed to collect spinal stiffness measures.

Meso-Scale Kinematic Responses of Asphalt Mixture in Both Field and Laboratory Compaction

Compaction is one of the most critical steps in asphalt pavement construction. Traditional compaction relies heavily on engineering experience and post-construction quality control and can lead to under/over compaction problems. The emerging intelligent compaction technology has improved compaction quality but is still not successful in obtaining mixture properties of a single pavement layer. Besides, very few studies have discussed the internal material responses during field and laboratory compaction to explain the meso-scale (i.e., particle scale) compaction mechanism. Knowledge in those areas may greatly promote the development of smart compaction. Therefore, this study aims to investigate the kinematic behavior of the asphalt mixture particles (translation and rotation) under six types of field and laboratory compaction methods and establish the relationship between the field and the laboratory compaction by using a real-time particle motion sensor, SmartRock. It was found that particle movement pattern was mainly affected by the compaction mode. At the meso-scale where particle behavior is the focus, the kneading effects of a pneumatic-tire roller can be simulated by laboratory gyratory and rolling wheel compaction, and the vibrating effects of a vibratory roller can be simulated by Marshall compaction. However, none of those laboratory compaction methods can completely simulate the field compaction. Under vibratory rolling, particle acceleration decreased fast in the breakdown rolling stage. Under pneumatic-tire rolling, particle angular position change was related to aggregate skeleton, and particle relative rotation showed a decreasing trend that was consistent with the laboratory gyratory compaction results. Those kinematic responses can potentially be used to monitor density change in field compaction.

THE PROCESSES OF ROLLING WHEEL AND TRACK SYSTEMS OF HOISTING-AND-TRANSPORT, CONSTRUCTION, ROAD VEHICLES AND OTHER BODIES INFLUENCED BY FORCE FACTORS. FIFTH LECTURE

The article consistently sets forth the material of the fifth lecture on the course “Theory of hoisting-and-transport, construction, road vehicles and equipment”, including the interaction of running wheels of tower, bridge and gantry cranes with guides (rails) and determining the resistance forces in the running gear of cranes and freight carts; interaction of roller hard wheels and elastic pneumatic tires with soils and coatings. HTCRVE caterpillar movers and their interaction with soils, as well as the motion of a non-circular solid body on an inclined surface, are considered.

Improvement of Diagnostic Parameters of a Rolling Wheel with Flat Spot and Experimental Test on Lithuanian Railways

The JSC (Joint-Stock Company) “Railway Products Conformity Assessment Center”, under a contract with JSC “Lithuanian Railways”, carried out a rolling stock geometry and rolling surface defect risk assessment study which analyzed the principles and algorithm of the ATLAS-LG system used by JSC “Lithuanian Railways” and the system’s advantages and similarities with other systems used for rolling surface defect prediction worldwide. According to the results of this study, JSC “Voestalpine VAE Legetecha” made changes to the algorithms of its ATLAS-LG computing system and changed the parameter used to determine the damage to wheelsets. The goal of this work was to review the automatic systems of rolling stock used to evaluate the state of the rolling stock, compare the criteria for culling, describe the methodology for setting a new parameter for detecting wheel damage Pderivative instead of the previous parameter Kdm, and upgrade operational algorithms of ATLAS. This paper describes the algorithm and methodology for setting a new parameter, evaluating the construction of rolling stock and movement speed. To develop a replacement algorithm for the ATLAS-LG system, a new parameter verification methodology using the inverse Laplace transform for the mathematical model was used.