Fuel consumption costs are an essential part of life-cycle cost analysis. These costs are influenced by vehicle technology, pavement condition, roadway geometrics, environment, speed, and other ...factors. Many models for the effects of pavement condition on fuel consumption were developed on the basis of data generated years ago in other countries for vehicles that vary substantially from those used currently in the United States. Therefore, new information is needed to help in refining and developing models that would better apply to U.S. conditions. The mechanistic model developed as part of the Highway Development and Management software (HDM-4) is recommended after calibration for predicting fuel consumption. The results of the calibration exercise for U.S. conditions, with field data collected as part of the NCHRP Project 1-45, are presented. The calibrated HDM-4 fuel consumption model was able to predict very adequately the fuel consumption of five different vehicle classes under different operating, weather, and pavement conditions. The better accuracy achieved after calibration has improved the prediction of the effect of roughness on fuel consumption. The comparison of sensitivity analyses before and after calibration has shown that the effect of roughness on fuel consumption increased by 1.75 for the van, 1.70 for the articulated truck, 1.60 for the medium car, 1.35 for the sport utility vehicle, and 1.15 for the light truck.
Fuel consumption costs are an essential part of life-cycle cost analysis. These costs are influenced by vehicle technology, pavement condition, roadway geometrics, environment, speed, and other ...factors. Many models for the effects of pavement condition on fuel consumption were developed on the basis of data generated years ago in other countries for vehicles that vary substantially from those used currently in the United States. Therefore, new information is needed to help in refining and developing models that would better apply to U. S. conditions. The mechanistic model developed as part of the Highway Development and Management software (HDM-4) is recommended after calibration for predicting fuel consumption. The results of the calibration exercise for U. S. conditions, with field data collected as part of the NCHRP Project 1-45, are presented. The calibrated HDM-4 fuel consumption model was able to predict very adequately the fuel consumption of five different vehicle classes under different operating, weather, and pavement conditions. The better accuracy achieved after calibration has improved the prediction of the effect of roughness on fuel consumption. The comparison of sensitivity analyses before and after calibration has shown that the effect of roughness on fuel consumption increased by 1.75 for the van, 1.70 for the articulated truck, 1.60 for the medium car, 1.35 for the sport utility vehicle, and 1.15 for the light truck. Show References
•Functionally graded materials (FGM) beams under bilateral constraints•Experimental testing and theoretical and numerical validations•Systemic study on the influences of geometric and material ...parameters•Material topology for optimization of material functions
In recent years, the study of Functionally graded materials (FGM) opened exciting new venues for the control and manipulation of engineered materials and structures. In this study, we investigate bilaterally constrained FGM beams with programmable material functions. The FGM beams are fabricated using 3D printing techniques, and tested t understand the behavior of structural instability (i.e., postbuckling) under the bilateral confinements. Theoretical and numerical models are developed to investigate the postbuckling response, and the results are compared to experimental observations with satisfactory agreements. Material topology optimization is then carried out to investigate the influences of the material functions on the release of the stored energy during the bucking mode transitions in the FGM beams. It is found that stored energy variations can be used to optimize the material functions, which allows for the guided design of bi-walled FGM beams with well-defined controllability over the structural instability. The reported bilaterally constrained FGM beams with optimized material functions can be used in a multitud of different applications.
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Parts obsolescence has an important impact on the product life cycle, the manufacturing system and the environment leading to operational, logistical, reliability and cost implications. While current ...resolution models are cost-oriented, multiple studies have revealed that technological obsolescence is strongly involved in the electronic waste problem. In this study, based on academic literature and expert opinions, a sustainable decision framework for obsolescence resolution strategy (ORS) selection is proposed. It consists of economic, environmental, social and technological dimensions, integrating a total of fifteen criteria. Multicriteria decision-making (MCDM) methods are suggested to select the most sustainable solution. A case study was performed where the criteria weights and the alternatives performance were judged by five experts from the fields of environment, economy, human resources and obsolescence and operations management. Results from different MCDM methods were compared to the actual decision to evaluate their effectiveness. Using the suggested framework improved the decision process as integrating sustainability had a drastic impact on the selected strategy and consequently on the company’s performance. In addition to its managerial insights, this paper provides a new research perspective to sustainable and robust obsolescence management to effectively handle the increasing number and severity of obsolete components.
This paper presents a summary of findings on the effect of pavement roughness international roughness index (IRI) and texture mean profile depth (MPD) on vehicle operating costs. The most important ...cost affected by roughness was fuel consumption, followed by repair and maintenance, then tire wear. An increase in IRI of 1 m/km (63.4 in./mi) increased fuel consumption of passenger cars by 2% to 3%, regardless of speed. For heavy trucks, this increase was 1% to 2% at 70 mph and 2% to 3% at 35 mph. Surface texture and pavement type had no effect on fuel consumption for vehicle classes except heavy trucks. An increase in MPD of 1 mm (0.039 in.) increased fuel consumption by 1.5% at 55 mph and 2% at 35 mph. The effect of pavement type on fuel consumption was statistically not significant for all light vehicles and was statistically significant for heavy trucks only at 35 mph in summer conditions (308C). No data were available for heavy trucks in winter. For repair and maintenance, there was no effect of roughness up to an IRI of 3 m/km (190 in./mi). Beyond this range, an increase in IRI up to 4 m/km (254 in./mi) increased repair and maintenance costs by 10% for passenger cars and heavy trucks. At an IRI of 5 m/km (317 in./mi), the increase was up to 40% for passenger cars and 50% for heavy trucks. An increase in IRI of 1 m/km (63.4 in./mi) increased tire wear of passenger cars and heavy trucks by 1% at 55 mph.
The structural rolling resistance (SRR) is the component of rolling resistance that occurs because of the viscoelastic deformation of the pavement structure. In this paper, a simple model to ...calculate the energy dissipation as a result of the SRR on rigid pavements is developed for use in applications such as life cycle cost analysis and life cycle assessment. First, the energy dissipated by different vehicles was calculated on 12 concrete pavement sections using a fully mechanistic approach. Using the program DYNASLAB to simulate the vehicles moving along the pavement sections, the energy dissipation was calculated as the work done by the vehicle to overcome the slope seen by the wheels because of the pavement deformation. The results were then used to develop a simple and rapid-to-use model to predict the energy dissipation on any jointed concrete pavement. The model consists of a simple predictive function that can provide the value of the SRR energy dissipation given the mechanical properties of the pavement section (slab thickness and stiffness, modulus of subgrade reaction, subgrade damping coefficient, pavement geometry, and load transfer efficiency) and the loading conditions (speed and loads). The model was based on a sensitivity analysis that was used to select the optimal set of structural and environmental factors.
In this paper, a new in situ method for determining the structural rolling resistance (SRR), defined as the dissipated energy caused by deformation of the pavement when subjected to a moving load, is ...presented. The method is based on the relation between SRR and the slope of the deflection basin under a moving load. Using the Traffic Speed Deflectometer, the deflection slope is measured at several positions behind and in front of the right rear-end tire pair of a full-size truck trailer while driving under realistic conditions. The deflection slope directly under the tire is estimated from a linear interpolation between the two nearest sensors. A set of data from a test road segment located in Denmark is analyzed and the SRR coefficients are found to be in the range 0.005% to 0.05%. The deflection slope measurements have a high reproducibility (repeated measurements agree within standard deviations of 4% to 10%) with high spatial resolution, and the method for calculating SRR from these measurements has the clear advantage that it requires no knowledge or model of the pavement structure or viscoelastic properties. Numerical simulations of pavement response show that the proposed interpolation method tends to underestimate the actual SRR, and better estimates can be obtained by other interpolation schemes.
Reduction in vehicle fuel consumption is one of the main benefits considered in technical and economic evaluations of road improvements. The study described in this paper investigated the increase in ...vehicle energy consumption caused by the structural response of a concrete pavement to a moving load. First, the day and night falling weight deflectometer deflection time histories were measured for three concrete sections; their mechanical characteristics were then backcalculated. Second, a finite element model (DYNASLAB) was used to determine the pavement structural response under moving load for all three sections under different wheel loading conditions (passenger car, SUV, and articulated truck), vehicle speeds, and temperatures. As the rolling wheels move forward, the local deflection basin caused by the delayed deformation of the subgrade and the rotation of the slab form a positive slope. The energy dissipated was calculated as the energy required for a rolling wheel to move uphill. Finally, the calorific values of gasoline and diesel were used to convert energy into fuel consumption excess. The maximum deflection-induced energy consumption is about 0.08% of the total consumption for articulated trucks, which is small compared with 1.9% for asphalt pavements at high temperatures and low speeds, as reported by other studies.
While clustering is a powerful methodology used for grouping objects into families, it is hard to conceive a natural object grouping method without considering the context of a particular ...application. In high-dimensional problems with large volumes and rapidly evolving part flows, many clustering methods have traditionally been used to form part families considering similarities. In this paper, a two-phase clustering method is developed to optimize the grouping process under technological constraints, in a bid to improve resource planning. The first phase consists in forming part families using the Agglomerative Hierarchical Clustering approach, considering multidimensional parametrization of the part, while in the second phase, the optimal number of clusters is determined using ELECTRE III, which serves to handle uncertainty. Based on a real case study in the electronics industry, an improved production planning solution is proposed to validate the method’s efficiency. The solution was compared to the in-use method to highlight its added value.
A new backcalculation program, DYNABACK-VE, was used to backcalculate pavement layer properties with field data. DYNABACK-VE used a time domain viscoelastic dynamic solution (ViscoWave-II) as a ...forward routine and a genetic algorithm for backcalculation analysis. The genetic algorithm search method was selected because it had a high potential for converging efficiently to a global solution. The forward solution used continuous integral transforms (Laplace and Hankel) that were more appropriate for transient, nonperiodic signals in the time domain. The algorithm was implemented in C++ and coded for parallel processing with multithreading for achieving better computational efficiency. Field falling weight deflectometer load and defection sensor time histories from three sites (Waverly Road near Lansing, Michigan, and two long-term pavement performance sections) were used for validation. The backcalculated asphalt concrete modulus master curves were compared with those obtained from laboratory testing. Very good agreement was obtained. The new algorithm was capable of backcalculating reliably the master curve of the asphalt concrete layer (four sigmoidal coefficients and two time-temperature shift factors), the elastic moduli for the unbound base or subbase and subgrade materials, and the modulus of stiff layer and the depth to stiff layer, if present. The advantage of the new solution is that it can analyze the response of pavement systems in the time domain and can therefore accommodate time-dependent layer properties and incorporate wave propagation. Also, because the backcalculation is performed in the time domain, the algorithm is not sensitive to truncation in the deflection time histories. This is a significant improvement to the state of the art, since truncation of deflection time histories has prevented frequency domain backcalculation solutions from being successful when measured field data are used.
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