Processes of Small Culvert Inspection and Asset Management

Proper drainage is essential for pavement to maximize life expectancy and minimize maintenance. Culverts are a critical asset to facilitate drainage. As with many assets, culverts deteriorate with age and require regular inspection. It is important to have a formalized process of inventory and inspection that is efficient and can effectively support culvert asset management. The current culvert inspection and asset management processes for the Indiana Department of Transportation (INDOT) have been modeled over the years on the bridge inspection process and were recently evaluated. A study was undertaken to further evaluate the current culvert asset management practices. Approximately 700 small culverts and catch basins were visited and evaluated using both the traditional culvert inspection practices and a revised asset management evaluation scale. The paper summarizes the findings of this evaluation and concludes by making recommendations for process improvements. These recommendations include the addition of photos to the culvert database, a revised rating scale, advanced planning of inspection schedules, a formalized process for culvert reassessments, the creation of a separate catch basin inlet inventory, various improvements to the inventory process, and a dedicated staff to complete inspections efficiently. It is also noted that building a reliable database will show historical trends and can eventually lead to a study of small culvert inspections and culvert longevity, which will lead to improved asset management

Evaluation of the anisotropic mechanical properties of reinforced polyurethane foams

The mechanical impact of adding milled glass fibers and nanoparticles at different mass fractions to low-density (relative density < 0.2) polyurethane (PU) foams is investigated. Tensile, compressive, and shear stress–strain curves are measured in the plane parallel to the foam-rise direction and the in-plane components of the elastic modulus are determined in order to assess the mechanical anisotropy of the foams. Power-law relationships between the moduli and apparent density are established for pure PU foams and used as a baseline to which the properties of composite foams are compared. Cellular mechanics models based on both rectangular and Kelvin unit-cell geometries are employed to estimate changes in the cell shape based on the mechanical anisotropy of composite foams, and the model results are compared with direct observations of the cellular structure from microscopy. A single measure of foam stiffness reinforcement is defined that excludes the effects of the apparent foam density and cell shape. The analysis reveals the large impact of cell shape on the moduli of the glass-fiber and nanocomposite foams. Nanocomposite foams exhibit up to an 11.1% degree of reinforcement, and glass-fiber foams up to 18.7% using this method for quantifying foam reinforcement, whereas a simple normalization to the in-plane modulus components of the pure PU foam would indicate from ?40.5% to 25.9% reinforcement in nanocomposite foams, and ?7.5 to 20.2% in glass-fiber foams

Fatigue behaviour of SiC p -reinforced aluminium composites in the very high cycle regime using ultrasonic fatigue

The fatigue behaviour of a 2009/SiC/15p-T4 DRA composite has been examined in the very high cycle fatigue (VHCF) regime where 10 7 ≤ N f ≤ 10 9 cycles. Ultrasonic fatigue was used to achieve the very high cycle counts. Careful processing yielded a composite with a very homogeneous particle distribution with minimal clustering. Fatigue crack initiation was observed almost exclusively at AlCuFe inclusions with no crack initiation observed at SiC particle clusters. Fatigue lives at a given stress level exhibited minimal scatter and subsurface crack initiation was observed in all cases. This behaviour is consistent with the presence of a low number density of critical inclusions that are responsible for crack initiation very early in fatigue life.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73177/1/j.1460-2695.2006.00998.x.pd

Modelling of the Viscoplastic Behaviour of Homogeneous Solid Propellants

This study is concerned with the mechanical properties of homogenous solid propellants. The experimental results demonstrate the high strain rate sensitivity of these materials. A modified viscoplastic model of the Bodner- Partom type was applied to simulate the nonlinear behaviour of solid propellants when subjected to uni-axial loading conditions. The material parameters of the constitutive law were identified numerically using the evolutionary algorithm. The capability of the proposed approach was investigated for a representative solid fuel sample. The efficiency of the method is discussed