Tyler Dare

The effect of grinding and grooving on the noise generation of Portland Cement Concrete pavement

In this investigation, studies have been done to understand the effects of various grinding and grooving parameters to investigate their effect on noise generation at the tire‐pavement interface. Grinding uses diamond‐infused blades that are closely‐spaced such that the fins between the blade tracks break off exposing an entirely new surface. For grooving, the blades are more widely spaced such that the fins do not break off and the surface texture remains largely unchanged except for grooves that are used for moisture control. Both procedures, used independently or in combination, have an effect on the noise produced by the tire‐pavement interaction. Variation of grinding parameters was shown to have as much as a 3 dB effect on noise generation. Variation in grooving parameters has a secondary effect, which allows grooves to be added to texture without overall effect on overall noise. This paper will illustrate the effects on noise of the different parameters, such as grinding depth, blade width, and blade spacing, for grinding and grooving.

A hybrid approach for simulating fluid loading effects on structures using experimental modal analysis and the boundary element method.

Many structural acoustics problems involve a vibrating structure in a heavy fluid. However, obtaining fluid-loaded natural frequencies and damping experimentally can be difficult and expensive. This paper presents a hybrid experimental-numerical approach to determine the heavy-fluid-loaded resonance frequencies and damping of a structure from in-air measurements. The approach combines in-air experimentally obtained mode shapes with simulated in-water acoustic resistance and reactance matrices computed using boundary element (BE) analysis. The procedure relies on accurate estimates of the mass-normalized, in vacuo mode shapes using singular value decomposition and rational fraction polynomial fitting, which are then used as basis modes for the in-water BE analysis. The method is validated on a 4.445 cm (1.75 in.) thick nickel-aluminum-bronze rectangular plate by comparing natural frequencies and damping obtained using the hybrid approach to equivalent data obtained from actual in-water measurements. Good agreement is shown for the fluid-loaded natural frequencies and one-third octave loss factors. Finally, the limitations of the hybrid approach are examined.

Research on a laboratory technique for tire-pavement noise assessment of asphalt mixes

Abstract Communication noise is classified as one of the pollutions for the current environment. Experimental techniques to measure tire-pavement noise generation from asphalt pavements in the laboratory have been limited. A series of experiments were conducted on six different asphalt mixtures to determine if Purdue University’s Tire-Pavement Test Apparatus (TPTA) could be used to overcome these limitations. The procedure produced samples with low tire-pavement noise; however, the air void contents of the samples were higher than designed. Despite these difficulties, the sample preparation technique and the TPTA testing protocol were shown to offer an effective approach for quick laboratory assessment of tire-pavement noise characteristics of hot mix asphalt pavements at a substantially reduced cost compared to field testing.

Effects of contraction joint width, fill condition, faulting and beveling on wheel-slap noise

The noise generated when a tire impacts a contraction joint, often called wheel-slap or joint-slap noise, can increase tire-pavement noise in Portland cement concrete roadways by up to 3 dB as well as increase annoyance appreciably. Wheel-slap noise has a much higher peak pressure level than tire-pavement noise measured without joints. Therefore, it is important to understand methods for control and reduction of wheel slap noise. In this paper, wheel-slap noise was measured on joints with widths varying from 5�24 mm. The joints were also tested full, half-full, and empty of silicone sealant, and with step-up and step-down faulting conditions of up to 6 mm. Finally, the wheel-slap noise levels of joints with beveled edges were measured and compared to levels from standard joints to investigate the effects of beveling and spalling of pavements on wheel-slap noise

Noise generation in contraction joints in Portland cement concrete.

Contraction joints between slabs of Portland cement concrete have a major impact on measured tire‐pavement noise levels. It has been proposed that during the interval when the contact patch of the tire is over the joint, the system acts as a Helmholtz resonator, and that this mechanism is responsible for the majority of the increased noise due to contraction joints. In this paper, this mechanism is investigated through theoretical calculations and experimentation. Intensity probes were used to measure noise near joints of varying widths using Purdue University’s Tire‐Pavement Test Apparatus (TPTA). The TPTA was used to discover relationships between vehicle speed, joint width, and measured sound pressure and sound intensity spectra near the joint and the tire.

The acoustic guitar as an experimental platform to teach vibration measurements, modal parameter estimation, and data management

The laboratory class required by Penn State’s Graduate Program in Acoustics teaches general experimental methods for acoustics. Students learn the basics of data acquisition, sensor calibration and excitation methods through lectures and performing experiments. This talk will discuss the lab experiment used to teach vibration measurements, basic modal parameter estimation and data management using an acoustic guitar as the experimental testbed. Students are required to develop their own test plan for accelerometer and impact hammer locations and then collect the data using a custom-written LabVIEW data acquisition program. Since the data acquisition involves multiple impact and response locations, the students are required to manage their data in a way that allows for easy mapping of data files to spatial locations. They then estimate the guitar body mode shapes by decomposing the measured mobility matrix into its singular values and right- and left-singular matrices. Finally, the students visualize their...

Cluster-based reduced-order modeling to capture intermittent dynamics of interacting wakes

Interacting flows are found in a range of aviation-relevant technologies, including flow control devices, engine combustors and augmentors, and aerodynamic control surfaces. The structure and dynamics of interacting jets and wakes, including both large-scale coherent dynamics and turbulent fluctuations, is fundamentally different from that of a single flowfield. The goal of this work is to understand large-scale, intermittent dynamics of turbulent interacting wakes and jets using an improved reduced-order modeling strategy, cluster-based reduced-order modeling (CROM), to capture these dynamics. We compare the dynamics of a three-wake system at two spacings to that of a single wake flowfield using the cluster-based method. The CROM is able to capture the expected dynamics of the single wake, and the results are analogous to those from proper orthogonal decomposition. However, CROM reveals a much more complicated set of dynamics in the interacting wake cases, including the existence of two sets of dynamics that intermittently appear and the switching points between them, that the POD was unable to detect. CROM is used to quantify these dynamics and understand the effect of bluff-body spacing on the three-wake flowfields.

Force Reconstruction Using Force Gauges and Accelerometers

Methods of inferring excitation forces from measured accelerometer data have received significant attention in recent years. This paper attempts to combine these techniques with the addition of force gauges to determine excitation forces on a vibrating structure. A mathematical algorithm was derived and applied to experimental data where a known impact force was applied to a plate mounted through force gauges. This experiment was used both to validate the mathematical algorithm and to investigate its limitations. The results show that the applied force for a fixed structure can be reconstructed better than force gauges alone using a combination of force gauge data and free boundary condition modal analysis.

Nonlinear, statistical models of tire-pavement noise

Tire-pavement noise is the result of a complex system of noise generation mechanisms and is affected by several different pavement and atmospheric parameters. Accurately predicting tire-pavement noise from given a set of parameters has proven difficult for researchers. The purpose of this research was to explore a wealth of pavement, atmospheric and noise data taken at the MnROAD pavement test facility and to develop a model to predict tire-pavement noise on asphalt pavements. Using a series of sub-models, variables significant to noise generation were identified. Finally, two variations of a model of noise generation were developed, each capable of predicting one-third octave band on-board sound intensity (OBSI) spectra. The model was developed using a hybrid statistical-experimental approach and was able to predict overall OBSI levels to within 1.5 dB for 80-90% of the pavements tested.

Comparing Tests for Near-Grazing-Incidence Noise Reduction and Sound Absorption Tests for Hot-Mix Asphalt

Sound absorption measurements have been used as a simple, cost-effective way of assessing pavement noise properties in the laboratory. However, tire–pavement noise (TPN) is emitted close to the pavement at shallow angles of incidence between the tire and a roadside receiver. Absorption properties can be used to predict oblique incidence noise properties, provided that certain assumptions are met. Near-grazing-incidence predictions of noise vary widely, and the assumptions involved may not be applicable to porous asphalt pavements. A method of directly measuring near-grazing-incidence noise reduction of hot-mix asphalt pavements was designed. It was found that the results of the proposed test could not be predicted from absorption data alone except for dense-graded pavement. For porous or thin, gap-graded pavements, the near-grazing-incidence test gave additional useful information about the acoustic performance of the pavement samples. The test can be used to supplement absorption and other laboratory tests for more accurate predictions of TPN.