Sound intensity measurement techniques, that used a two-microphone setup, were first developed in the late 1970s. Back then, the focus was on improving precision during testing or post-processing because the equipment available was inherently inaccurate. However, with the advent of modern, sophisticated equipment, the focus has shifted to the apparatus. Availability of phase-matched microphones has made post-test correction obsolete as the microphones eliminate a majority of the errors before the data is even collected. This accuracy, however, comes at a price, as phase-matched microphones are highly priced. This paper discusses employing the method of improving post-processing precision, using inexpensive, current equipment. The phase error of the system is corrected using a simple calibration technique and a handheld phase calibrator that is similar to the one used for amplitude calibration of microphones.
Introducing a new transducer concept has resulted in considerable reduction in setup time and at the same time improved accuracy and repeatability for engine bay noise transfer studies. The acoustic environment inside cars are one of the primary comfort parameters. This is made up of a number of contributions from drivetrain, auxiliary equipment, wind noise and tire noise, and all are influenced by the transfer from the source to the receiver. With the change from purely internal combustion engines to electrical or electrical assisted propulsion systems, a new set of noise sources are introduced in the engine compartment and this requires renewed focus on the transmission paths to the receivers inside the car cabin. Typically, one of the tools to study these mechanisms is by using a reverse transmission technique, placing a well-defined sound source in the receiver position inside the car and measure the resulting sound pressure levels in the engine compartment.
Off-highway equipment operates in residential communities and must meet their radiated noise targets to be compliant with noise regulations and to be competitive in the marketplace. Traditional find and fix noise testing of late-stage prototype designs may cause launch delays, with intense time pressures that often result in missed opportunities to create excellent products with good value. Accurate simulation of noise from these machines allows noise targets to be assessed at each stage of product development, giving engineers time to develop low noise products without adding excessive manufacturing cost. Simulation of an early prototype of a new vacuum excavator showed excessive levels of radiated noise in two different frequency ranges. Further investigation of the simulation results of these two spectrum ranges indicated different noise mechanisms producing the excessive noise levels.
When it comes to the design of multi-functional automotive interior floors, engineers face the challenging conflict between a dynamically-soft, NVH performing treatment, and a statically-stiff construction, which increases the perception of solidity. Nowadays, the former requirement is well-specified and advanced CAE tools exist to support performance prediction and engineering of the construction. On the contrary, neither well-established requirements specify the compressional performance, nor defined CAE processes are available to support the engineer in its prediction. In this context, the aim of this paper is twofold. Firstly, insightful conclusions about the compression behavior of typical interior floor materials are drawn by means of tests carried out both at sample- and part-level. Such an assessment allows highlighting a clear direction towards meaningful assessment of the mechanical characteristics of the floor.
Since the automobile development time becomes shorter and shorter every year in the current trend in automobile industry, OEM's NV engineers are often required to analyze vehicle systems and components in early stage in development, where the design constraints are still not severe. This analysis are refined further to parts and then to flat sample requirements. As a result, trim suppliers in the automobile industry are given Insertion Loss (IL) and Absorption Coefficients (AC) requirements for their material to satisfy. Quite often this IL and AC requirements pertain to flat sample data. Additionally, trim suppliers catalog flat sample IL and AC for most materials they have in stock and some of their competitors' materials to benchmark. Flat sample data are valuable but should not be used as the only metric in order to decide which material will be applied onto a full vehicle.
This paper will discuss the background and history of "laminated steel" (commonly called "noiseless steel" or "MPM". It will provide the early development, where it came from and how it was introduced to North America as a new tool for engineering acoustical solutions. A progressive timeline will show laminated steel from its earliest inception and application in Europe to its current role in today's global market. Case histories along with examples of successful applications will detail its important contribution in advancing the technology for component damping. Many manufacturing sources as well as end-users have been impacted over the the decades since it was introduced. Many of these companies will be highlighted.The background information for this paper is provided by many of the individuates who were involved in the very early stages of its introduction as well as those who are currently working to utilize the technology of "laminated steel".
Though the idea of masking the undesired tonal and intermittent noises arising from local ancillary elements of the powertrain of electric vehicles is clear for many automotive manufactures, the acoustic nature of such masking sound is still under development. Since this masking sound need also to represent their brand sound DNA, it needs to be creatively designed and clinically derived. As the task to bridge the design ideas into real vehicles involves usage of range of processes and extensive toolchains i.e. sound design creation, online parametrization via real tunings till the creation of production ready flash able datasets, this is the major ongoing challenge for automotive manufacturers. Considerably short development time and constraints in involved cost for such elaborative processes makes this task still tighter.
The likelihood appears as the natural tool to perform such comparisons as soon as the probability of a given result may be estimated. Vibroacoustic analysis mainly relies on complex matrix-valued Frequency Response Functions that can be easily measured and computed. The likelihood of such complex and frequency dependent matrices is investigated. A two stage statistical reduction, based on Independant Components Analysis, is proposed in order to separate statisticaly independent components with random complex amplitudes. Their probability may be computed independently from one to another one. The joint probability density fonction of the real part and of the imaginary part of each independent complex-valued random variables is estimated using a nonparametric stochastic model of model uncertainties implemented in MSC/NASTRAN and the Monte Carlo simulation method as a stochastic solver.
Vehicular Emission testing is gaining importance over the past years in the wake of requirements for real driving emissions with implementation of RDE packages across Europe / USA and various developing countries. Extending the same concept for other countries poses slight challenges in terms of geographical and climatical conditions prevailing in the country, where the climatical conditions are differing from Europe / USA. It is a challenge to accept the same boundary conditions as in Europe, at the same time the challenge is to find a threshold number in a more scientific manner. This study concentrates on determination and recommendation of thresholds for ambient temperature and altitude. The basis for temperature threshold would be to determine the percentage of time the temperature exceeded beyond the threshold over year in the country. The basis for Altitude is considered based on the percentage of total length of roads beyond the threshold altitude limit.
The automotive market need for shorter development cycles, as well as wider environmental concerns (climate change and poor air quality in cities), have promoted a revolution in digital engineering. Virtual hardware screening and engine calibration, before hardware is available, is a highly time and cost-effective way of reducing testing and shorting the time to bring product to market. Model-based development workflows, to be predictive, need to offer realistic combustion rate responses to different engine characteristics. The current approach, however, relies on empirically or experienced derived combustion responses, making the exploration of unconventional solution challenging. An alternative method that is less data and user experience dependent, is therefore needed. In this work a pragmatic engine development process based on a 0D combustion Stochastic Reactor Model (SRM) and in-cylinder cold CFD simulations is presented.
This paper presents yaw testing of vehicles with tread removed from tires at various locations on the vehicle. A 2004 Chevrolet Malibu and a 2003 Ford Expedition were included in the test series. Speeds up to 60 mph were achieved. The vehicles were instrumented to record speed, steering angle, yaw angle, wheel speeds, and other parameters. The tire marks on the roadway were surveyed and photographed. Critical speed analysis has long been used by Accident Reconstructionists for calculating speed at the beginning of a yaw. Traditionally, the method has been used to calculate the speed a vehicle with four intact tires. The critical speed model is extended to include the analysis of speed of vehicles following a tread detachment event. It was found that the critical speed formula produces results of acceptable and known accuracy provided the appropriate inputs are used for the given situation and several guidelines are observed.
Meter clusters display conventional warnings as well as complicated messages such as ADAS. Display systems of meter clusters are developed using model based development methods, which include two kinds of models: logic models and GUI models. GUI models display pictures and messages according to instructions of logic models' output, which are generally made using MATLAB/Simulink. Testing and validation for logic models have been already applied. GUI models are made by GUI tools which can be operated graphically. However, approximately 9 million manual operations are necessary for each system. In this way, GUI tools are bound to cause human errors and are hard to identify. An automatic layout tool has been developed to improve operation efficiency and reduce any human errors. The automatic layout tool for GUI tools has three functions: an arrangement function, a localize function, and, a check function. Each screen consists of 30 pictures and messages on an average.
Flexform™ is a high-pressure hydroforming technique using a flexible rubber diaphragm between the liquid pressure medium and sheet metal. No seal is needed between the metal sheet and the pressure medium. Only a lower tool half is required, as the diaphragm will act as a flexible upper tool half. Further, the flexible diaphragm allows for several tools to be used in one and the same forming operation. All kinds of sheet metal and thicknesses may be formed using the technique. Perforated sheets, pre-coated sheets, or sheets with sensitive surfaces in addition to traditional materials. The Flexform technique works well with difficult-to-form sheet materials such as ultra-high strength steel, titanium, and aluminum. However, as with any other cold forming method, spring-back is obtained after forming. High-pressure forming often leads to less spring-back than conventional stamping. Material spring-back is still a factor to take into consideration and needs to be controlled in some way.
Due to the continuously increasing complexity of automotive electric/electronic architectures (EEAs), model-based systems engineering principles became state-of-the-art for designing such heterogeneous systems. However, current Architecture Description Languages (ADLs) as well as their system-design and analysis tools and frameworks for simulation-based analysis of EEA models often are not fully integrated in a single design process. They usually require error-prone import/export processes, especially when considering distributed collaboration, from EEA data models to external analysis frameworks and vice versa. Particularly, this limits the efficient assessment and comparison of distinct architecture variants regarding certain non-functional properties. Moreover, simulation-based analysis of the latter intended for EEA assessments in early concept phases demands backtracking capabilities to allow iterative model adaptations.