bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Heat Transfer in Magneto-Micropolar Fluids Flow Past a Vertically Expanding Sheet Featuring Prescribed Wall Temperature (PWT)
Authors: Fatunmbi Ephesus Olusoji , Akanbi Olumuyiwa O. , Okoya Samuel Segun
Published: May 2023

This study assesses the motion and the dynamics of heat propagation in magneto-micropolar fluid along a sheet which vertically stretches on a two-dimensional plane in a porous material. The heat distribution is developed and evaluated under the condition of the prescribed wall temperature, constant magnetic field, thermal radiation, variable heat source and viscous dissipation. The main equations are re-formulated from partial to ordinary derivatives using similarity tools and consequently solved numerically by shooting and the Runge-Kutta Fehlberg approach. The parameters of interest are presented graphically to demonstrate their reactions on the velocity profiles, thermal field and heat transfer mechanism of the problem. The outcomes of the current investigation reveal that the heat transfer appreciates in the presence of higher Prandtl number, temperature exponent term and material parameter but decreases as the magnetic field term soars.Besides, the heat boundary structure expands and heat spread occurs as the thermal radiation, magnetic field and Eckert number terms escalates but a reverse trend is encountered as the Prandtl number, material micropolar term, Grashof number and heat exponent terms grows in magnitude. Under some limiting scenarios, the obtained data strongly correspond to the published studies in the open literature.
Studying the Oscillating Flow around Unconfined Obstacle of Elliptical Cross-Section
Authors: Tefiani Lotfi , Belharizi M. , Nehari D. , Hamoudi B.
Published: May 2023

The present paper focuses on the effect of geometric shape of a cylindrical body submerged in an oscillating flow by means of numerical investigations. The cylindrical body has an elliptic cross-section with a variation of its elliptic ratio (ratio between major and minor axes of the elliptic section). The flow direction is oriented along the major axis. Three regimes from (Tatstuno and Bearman) maps are studied namely, a symmetric regime A and two other asymmetric regimes D and F. The flow field structures, the Morison coefficients of longitudinal forces and the root mean square (r.m.s.) of transverse forces are computed with respect to the elliptic ratio variation. For the case of cylinders with slightly elliptic cross-section, vortices and pressure fields are very similar to those of a circular cylinder. For the case of regime A, the vortex shedding is always symmetric despite the unbreakable variation of the elliptic ratio. On the other hand, the reduction of the elliptic ratio weakens the asymmetry of the flow for regimes D and F. Moreover, the flow in each regime becomes completely symmetric at a given value of the elliptic ratio. In fact, the predicted longitudinal component of the force acting on the cylinder decreases with the reduction of this ratio. This results in the same manner on the behavior of Morison coefficients. With regard to the symmetric regime A, the transverse force does not manifest itself for all considered ratios. On the other hand, the transverse force in the case of asymmetric regimes decreases rapidly with increasing the ellipticity of the cylinder. The present study showed us that the inertia coefficient is sensitive to the vortex path; however, the drag coefficient is independent of the vortex path. Both coefficients depend simultaneously on Reynolds number and the geometric shape of the body.
The Transient Electroosmotic Flow of Maxwell Fluids and Heat Transfer in a Parallel Microchannel Using Caputo Fractional Derivative
Authors: Tahiru Adamu G. , Yakubu Dauda Gulibur , Abdulhameed Mohammed , Baba Ali M. , Abubakar Bishir , Abdullahi Isah
Published: May 2023

In this work, we consider transient electroosmotic flow of fractional Maxwell fluids model derived for both velocity and temperature in a micro-channel. We use the Poisson-Boltzmann equation to describe the potential electric field applied along the length of the micro-channel. Exact solutions of both velocity and temperature were obtained using Laplace transform combined with finite Fourier sine transform. Due to the complexity of the equations for velocity and temperature, the inverse Laplace transform was obtained using the numerical inversion formula based on Gaver Stehfest’s algorithms. The numerical solutions were simulated with the help of Mathcard software and the graphical results showing the effects of time, relaxation time, electrokinetic width and fractional parameters on the velocity of the fluid flow and the effects of time and fractional parameter on the temperature distribution in the microchannel were presented and discussed. The results show that the applied electric field, the electroosmotic force, electrokinetic width, and relaxation time play vital role on the velocity profile in the micro-channel and the fractional parameter can be used to regulate both the velocity and temperature in the micro-channel. The effects of the various influential parameters on both fluid velocity and temperature distribution were found to be useful for the design of microfluidic devices. These devices could be useful for biomedical diagnosis and analysis, for clinical detection of viruses and bacteria in biological processes. Keywords: Caputo fractional derivative, Electro kinetic width, Electroosmotic flow, Heat transfer, Zeta potential,
Prolonged liver transplantation survival and aging successfully
Authors: Pollicino Francesco , Dominguez Ligia J. , Barbagallo Mario
Published: May 2023

The traditional definition of successful aging as the absence of disease, disability, and cognitive impairment is not always applicable to patients with long survival despite complex multimorbidity. This case report details the situation of an 87-year-old man, currently partially self-sufficient and partially autonomous, without cognitive impairment, who has been affected with recurrent right knee osteomyelitis since the age of 6. A diagnosis of hepatitis C virus (HCV)-related liver cirrhosis at 41 led to liver transplantation at 56. The immunosuppressive anti-rejection therapy caused a relapse of chronic osteomyelitis and HCV infection, a major cause of graft loss and shortened survival in HCV liver transplant recipients. Other pathologies were also diagnosed during his lifetime. This patient is an example of aging successfully despite complex multimorbidity and disproves the traditional concept of successful aging formerly described in the literature.
Outcomes of Salvage Therapy for Oropharyngeal Cancer Recurrence Following Upfront Radiation Therapy and Prognostic Factors
Authors: Choi Nayeon , Kim Hack Jung , Yi Heejun , Kim Heejung , Kim Tae Hwan , Jeong Han-Sin , Son Young-Ik , Baek Chung-Hwan , Oh Dongryul , Ahn Yong Chan , Chung Man Ki
Published: May 2023

Purpose This study aimed to investigate the oncologic outcomes and prognostic factors of salvage treatments in patients with recurrent oropharyngeal squamous cell carcinoma (OPSCC) after radiotherapy (RT)-based treatment.Materials and Methods A cancer registry was used to retrieve the records of 337 patients treated with definitive RT or concurrent chemoradiotherapy (CRT) from 2008 to 2018 at a single institution. The poor-responder group (PRG) was defined as patients with residual or recurrent disease after primary treatment, and the oncologic outcomes for each salvage treatment method were analyzed. In addition, prognostic indicators of recurrence-free survival (RFS) and overall survival (OS) were identified in patients who underwent salvage treatment.Results After initial (C)RT, the PRG comprised 71 of the 337 patients (21.1%): 18 patients had residual disease, and 53 had recurrence after primary treatment (mean time to recurrence 19.5 months). Of these, 63 patients received salvage treatment (surgery 57.2%, re-(C)RT 23.8%, and chemotherapy 19.0%), and the salvage success rate was 47.6% at the last follow-up. The overall 2-year OS for salvage treatments was 56.4% (60.8% for the salvage surgery group and 46.2% for the salvage re-(C)RT). Salvage surgery patients with negative resection margins had better oncologic outcomes than those with close/positive resection margins. Using multivariate analyses, locoregional recurrence and residual disease after primary surgery were associated with poor outcome after salvage treatment. In Kaplan-Meier analyses, p16 status was significantly associated with OS in the initial treatment setting but not in the salvage setting.Conclusion In recurrent OPSCC after RT-based treatment, successful salvage was achieved in 56.4% patients who had undergone salvage surgery and radiation treatment. Salvage treatment methods should be selected carefully, given recurrence site as a prognostic factor for RFS.
FMVSS 141 for Commercial Vehicles: Applicability and Limitations
Authors: Seward Brett , Gorodisher Alex , Rubino Lorenzo
Published: May 2023

Newly manufactured light-duty hybrid and electric passenger vehicles must comply with FMVSS 141 minimum sound requirements to reduce the risk of crashes with visually impaired and inattentive pedestrians. Commercial vehicles operate in a variety of noise-critical environments, from densely packed industrial yards to congested urban areas, making safe electric vehicle operation around pedestrians and bystanders vital. Though the market share of medium and heavy-duty hybrid and electric vehicles is projected to increase annually, there are currently no North American regulations specifically for minimum sound emissions of hybrid and electric vehicles heavier than 10,000 lb. GVWR. The primary intent of this paper is to investigate the efficacy and limitations of the current FMVSS 141 requirements when applied to heavy-duty electric trucks. Serving as a complementary test case, a Class 8 Freightliner eCascadia electric truck with onboard Acoustic Vehicle Alerting System (AVAS) was evaluated at Daimler Truck North America’s High Desert Proving Grounds in accordance with the FMVSS 141 procedure for light-duty passenger vehicles. Analysis of the measured data found the FMVSS 141 forward gear criteria to be reasonably effective when applied to the test vehicle, but the standard’s reverse gear criteria were deficient to other common industry-accepted backing alert methods. These results are used as a starting point for a discussion on various aspects of FMVSS 141, with an emphasis on how adding commercial vehicles to the scope of the standard could necessitate further changes to the defined acceptance criteria.
Active Noise Cancellation Health Managing Method
Authors: Valeri Frank , De Cesaris Simona , Kolb Christoph , Schirmacher Rolf
Published: May 2023

Ensuring the robustness of vehicle systems and features is a key aspect of customer satisfaction and therefore is of vital importance to Original Equipment Manufacturers (OEMs). Both initial quality and quality over the life of the vehicle are important aspects to customers. Therefore, some features and systems require an active approach at monitoring system health. The intent of Active Noise Cancellation (ANC) systems in vehicles is to increase the customer’s perception of vehicle refinement and brand quality. Due to the nature of ANC system operation, it is critical that the system does not go divergent resulting in unwanted noise being heard by the customer. So, a method to monitor the ANC system operation and performance is required to ensure robustness. Despite tuning ANC systems considering expected vehicle build tolerances, vehicle aging and customer specific use cases, an ANC system can occasionally still go divergent in the field. An ANC audit procedure is included in the system software to verify functionality and performance at End of Line (EOL), repair centers or verified though an Over the Air (OTA) procedure. This type of procedure can verify the vehicle’s acoustic cavity response and update ANC tuning parameters to account for any changes. This paper will show vehicle examples of why an ANC health monitoring system is needed and how we developed, implemented, and utilized an ANC audit procedure to improve ANC system robustness and customer satisfaction.
Research on the Harmonics-Based the Optimization Algorithm for the Active Synthesis of Automobile Sound
Authors: Xie Liping , Chen Wan , Liu Zhien , Lu Chihua
Published: May 2023

The technology of active sound generation (ASG) for automobiles is one of the most effective methods to flexibly achieve the sound design that meets the expectations of different user groups, and the active sound synthesis algorithms are crucial for the implementation of ASG. In this paper, the Kaiser window function-based the harmonic synthesis algorithm of automobile sound is proposed to achieve the extraction of the order sounds of target automobile. And, the suitable fitting functions are utilized to construct the mathematical model between the engine speed information and the amplitude of the different order sound. Then, a random phase correction algorithm is proposed to ensure the coherence of the synthesized sounds. Finally, the analysis of simulation results verifies that the established method of the extraction and synthesis of order sound can meet the requirements of target sound quality.
NVH Considerations for Highly Asymmetric Laminated Glass in Electric Vehicles
Authors: Pruetz Jeffrey E. , Fisher W Keith , Govindswamy Kiran , Stirzinger Brett
Published: May 2023

The innovation and application of new technologies in battery electric vehicle (BEV) development continues to be a key objective of the automotive industry. One such area of development is glazing designs that reduce transmission of noise into vehicle interiors. Highly asymmetric laminated front side lites that consist of thick soda lime glass exterior plies laminated with thinner ion exchanged interior plies with acoustic polyvinyl butyral interlayers offer substantially reduced noise transmission compared to industry standard monolithic front side lites. These asymmetric laminate designs also provide additional benefits of improved toughness and penetration resistance. This paper documents a study that uses a systematic test-based approach to understand the sensitivity of interior vehicle noise behavior to changes in acoustic attenuation driven by installation of asymmetric laminated glass front side lites.

The test-based assessment included within this study was conducted to isolate the individual contributions and influence of wind, road, and powertrain induced interior noise shares associated with highly asymmetric laminated glass front side lite integration. To facilitate this separation and comparison, a multi-step process was conducted. First, a baseline BEV was characterized including operational, source, and transfer function measurements. This data was utilized to develop a time-domain noise transfer path analysis (TPA) model. Second, asymmetric laminated front side lites were replaced on the baseline EV and corresponding transfer functions were measured. Lastly, the asymmetric laminated glass transfer functions were exchanged in the TPA model to obtain interior noise shares associated with wind, road, and powertrain contributions. Based on the results from this comparison, improvement was observed in vehicle NVH performance using the highly asymmetric glass laminates, relative to conventional monolithic front side lites.
Modeling the Integration of Complex EV Systems into NVH Treatments Using Sound Phonons
Authors: Morris-Kirby Rod , Tinti Francesco Carlo
Published: May 2023

Current and future EV’s contain significant amounts of complex electrical hardware, including rechargeable energy modules, control units, cooling systems and wiring situated inside the cabin usually below the carpet, seats or trunk trim and below the cabin floor. These items, whilst likely to have a direct impact on transmission loss, are increasingly difficult to evaluate via typical methods of computer-based simulation. In particular, the packaging space allocated for control units, which may require an air gap between the body in white and the carpet for aspects of heat stabilization can be difficult to model using the transfer matrix method.

In the case of battery installations their high bulk mass doesn’t necessarily provide significant increases in transmission loss due to adjacent acoustic weaknesses and the inherent sensitivity of the floor system. This paper examines a selection of novel techniques, using sound Phonons, developed to predict both baseline transmission loss and absorption and subsequently acoustic performance optimization. The user-friendly nature of the sound Phonon application enabled “full vehicle” models to be efficiently created for interior and exterior noise prediction. This is particularly useful for EV target compliance evaluation when a platform is undergoing conversion from ICE to EV or assisting a “clean sheet” EV design.
SAE J1637 Vibration Damping Round Robin Study: Summary and Conclusions
Authors: Deshpande Satya , Moritz Charles
Published: May 2023

As part of the update process to SAE J1637, “Laboratory Measurement of the Composite Vibration Damping Properties of Materials on a Supporting Steel Bar”, the Acoustical Materials Committee commissioned a round robin study to determine the current laboratory-to-laboratory variation, and to better understand best practices for composite loss factor measurements. Guidance within the current standard from a previous round robin study indicates a coefficient of variation of 35% for laboratory-to-laboratory measurements. It was hoped that current instrumentation and test practices would yield lower variability. Over the course of 5 years, 10 separate laboratories tested 4 bars: three damped steel bars and one bare steel bar. The bars were tested at -20°C, -5°C, 10°C, 25°C, 40°C, and 55°C. The damping materials were intentionally selected to provide low damping, moderate damping, and high damping to illustrate difficulties in determining the composite loss factor with increased damping. Additionally, the differences between automated and manual data acquisition systems and contact and non-contact transducers are reviewed. The results of this study were used for the 2021 update to the SAE J1637 standard.
NVH Prediction for a Heavy-Duty Truck Vehicle Using Multi-Level FRF Based Sub-Structuring Approach
Authors: Ramanathan Vijay , P. A. Ramakrishnan
Published: May 2023

Increase in comfort requirements for noise and vibrations in commercial vehicles, demand for identifying major NVH issues and addressing them at design stages, thereby avoiding cost incurred due to design changes in later stages of the product development. This work majorly focusses on establishing an approach for predicting NVH performance of a heavy-duty truck using frequency response function based sub-structuring (FBS) methodology. This approach helps in reducing the overall solving time, specifically while analyzing for truck finite element models with large number of degrees of freedom. It majorly involves representation of all subsystems of a truck in the form of frequency response functions.

A detailed finite element model of a full truck is evaluated for NVH load cases such as vibration / noise transfer function studies and operational NVH load cases such as vehicle idle and dynamic gear run-ups. Cabin noise and tactile vibrations are the major operational NVH parameters predicted using the detailed model. Also, FRFs and cross-FRFs are evaluated for each of the subsystems of the full truck such as cab, cab suspension, chassis, chassis suspension at the hard points or integration points.

With the information available on FRFs and cross-FRFs of the major subsystems, a simplified model is developed using multi-level FBS, without finite element representation. The operational NVH parameters are predicted with the FBS model for all load cases and the FBS results observed to be in good agreement with detailed FE model results. Also, significant reduction in solving time of the full truck model is achieved.

The benefits of FBS approach can be further extended to a variety of other NVH developments such as mount stiffness optimization, evaluating design changes in the cab or chassis structure for NVH impact, consuming very less solving time.
Time-Domain Explicit Dynamic CAE Simulation for Brake Squeal
Authors: Song Gavin , Wang Arthur , Medhora Pari , Vlademar Michael , Venugopal Narayana
Published: May 2023

Disc brake squeal is always a challenging multidisciplinary problem in vehicle noise, vibration, and harshness (NVH) that has been extensively researched. Theoretical analysis has been done to understand the mechanism of disc brake squeal due to small disturbances. Most studies have used linear modal approaches for the harmonic vibration of large models. However, time-domain approaches have been limited, as they are restricted to specific friction models and vibration patterns and are computationally expensive. This research aims to use a time-domain approach to improve the modeling of brake squeal, as it is a dynamic instability issue with a time-dependent friction force. The time-domain approach has been successfully demonstrated through examples and data.
Experimental Validation of Vibration Isolation in Quasi-Zero Stiffness Mount Concept
Authors: Gusmano Paul , Fredette Luke
Published: May 2023

In the mounting of vibration sources and receivers, it is typically desirable to have low stiffness for isolation. On the other hand, durability may demand a high stiffness to handle large inputs without excessive motion, which seems like a contradictory requirement. Both may be achieved using nonlinear stiffness mounts which make use of elastomer deformation to exhibit softening through geometric nonlinearity. This paper discusses a physical proof of concept for a quasi-zero stiffness mount design with a three-regime stiffness curve including a preload, isolation, and motion control regions. Building on a design concept proposed in prior literature, new experimental validation is obtained for the prior nonlinear static stiffness property, which is then fit into a more stable mount topology. Fabrication and material issues are also discussed. Finite element models are used with material coupon tests to characterize the elastic properties of chosen materials, as well as predicting the stiffness behavior of the mount. Computational models are also used along with sinusoidal vibration measurements to assess the effect of damping, which is quantified with structural, viscous, and fractional calculus based damping models. Experimental validation of the new configuration is provided for both static and dynamic excitations.
Simulation and Validation of Stator Modes of a Hairpin Motor
Authors: Zhang Fulong , Ba Jing , Sun Zhaohui
Published: May 2023

With the trend of electric drive unit gradually replacing ICE powertrain, in additional to gear noise, the motor noise has become a new major NVH challenge. These tonal noises are easier to be detected in the pure electric vehicle that has no masking effect of ICE powertrain. Therefore, how to accurately predict and reduce the motor noise is a key to solve the problem. The accuracy of calculated motor stator modes determines the accuracy of motor noise prediction. This paper presents a simulation method based on the finite element model and defined orthotropic material properties of the stator. The material property parameters of the stator core and hairpin windings are reverse-engineered through iterative correlations to test data. High accuracy FEA model is achieved that can determine the stator mode shapes and frequencies of this hairpin motor accurately, which provides a reliable and effective approach for the motor noise prediction and optimization studies.
Noise Metrics and Subjective Assessment of Automotive HVAC Systems
Authors: Bennouna Saâd , Muhr Sebastian , Dutta Soumya , Liu Linbo , Kurniawan Darius
Published: May 2023

HVAC systems are of critical importance in ensuring passengers’ thermal comfort inside the car cabin as well as safety requirements for defogging functions. These systems involve various components and subcomponents such as blowers, thermal exchangers or actuators, with a wide range of well-known technologies and also new ones on recently introduced innovative products.

Currently, within established electrification trends worldwide, the HVAC system is becoming the most important embedded system that can induce major contribution of noise and vibration. These NVH issues can emerge through different transfer paths inside the car cabin possibly causing significant discomfort to passengers.

During developments, the NVH issues are mastered and contained by both suppliers according to internal requirements and OEMs according to specifications. However, OEM specifications are mainly defined by overall noise levels and improvements over the years are generally consisting of reducing these specified levels. Furthermore, some HVAC NVH issues may not be well detected when using regular NVH metrics. This raises concerns about the limitations of the regularly used metrics in ensuring specification compliance and, above all, in depicting a subjective assessment at component level.

Throughout a statistical analysis of HVAC systems population, this paper first focuses on the discrepancies between the data provided by traditional NVH metrics and subjective evaluations. Then, a deeper analysis involving psychoacoustic metrics provides a relevance overview of the applied metrics depending on the encountered issues and compared to a subjective assessment. Finally, from a responsibility perspective, these findings raise questions about the relevance of regular metrics used by OEMs and the right way to handle HVAC NVH topics nowadays.
A Lightweight Multilayer Dissipative Material with High Acoustic Performance
Authors: Gan KimTong , Herdtle Thomas , Anderson Brian , Yoo Taewook
Published: May 2023

A multilayer acoustic treatment constructed of fibrous acoustic absorption material combined with dissipative acoustic material achieves a low profile and is lightweight and multi-functional, with properties that are desirable for NVH (noise, vibration, and harshness) treatments. The dissipative material consists of microfibers and acoustically active particles; this material was introduced in the last SAE NVH conference: A Novel Dissipative Acoustic Material [1].

In this paper, the acoustic performance of the multilayer treatment was evaluated by using random incidence absorption and transmission loss measurements, as well as in-vehicle experiments. Absorption and transmission loss were additionally modeled using the transmission matrix method (TMM). In the in-vehicle test, an OEM wheelhouse liner with Trim, for an SUV, was evaluated utilizing this new multilayer 3M treatment.
An Experimental Investigation of the Acoustic Performance of a High-Frequency Silencer for Turbocharger Compressors
Authors: Sriganesh Pranav , Selamet Ahmet
Published: May 2023

Conventional silencers have extensively been used to attenuate airborne pressure pulsations in the breathing system of internal combustion engines, typically at low frequencies as dictated by the crankshaft speed. With the introduction of turbocharger compressors, however, particularly those with the ported shroud recirculating casing treatment, high-frequency tones on the order of 10 kHz have become a significant contributor to noise in the induction system. The elevated frequencies promote multi-dimensional wave propagation, rendering traditional silencing design methods invalid, as well as the standard techniques to assess silencer performance. The present study features a novel high-frequency silencer designed to target blade-pass frequency (BPF) noise at the inlet of turbocharger compressors. The concept uses an acoustic straightener to promote planar wave propagation across arrays of quarter-wave resonators, achieving a broadband attenuation. The effectiveness of the silencer is evaluated on a turbocharger gas stand where the compressor is the noise source. The experiment utilizes a unique rotating inlet duct upstream of the silencer to perform a modal decomposition of the acoustic field in order to compute sound power levels across the operating flow range at various compressor rotational speeds. The results are then compared to those from an earlier experiment with a straight duct installed at the compressor inlet to determine silencer insertion loss, defined here as the difference between upstream (with respect to flow direction) sound power levels without and with the silencer. The study also addresses the resulting compromise in compression system performance and noise generated due to flow-acoustic coupling within the silencer. Hence, the current effort demonstrates the effectiveness of a novel silencer in terms of insertion loss derived from a modal decomposition of the multi-dimensional acoustic field at the compressor inlet.
Beamforming Quantification of Acoustic Transmission Paths for Passenger Vehicles Using a Reciprocal Approach
Authors: Oettle Nicholas , Graham Samuel , Sims-Williams David , Riegel Matthias , Hebestreit Ramon
Published: May 2023

This paper presents an experimental method for measuring transmission paths from the exterior to the interior of a passenger vehicle using a reciprocal approach: A production vehicle was placed in a semi-anechoic environment; artificial noise sources were placed at the location of the occupant’s ear(s) inside the vehicle and beamforming arrays with a total of more than 300 microphones were used to observe apparent noise sources on the vehicle exterior resulting from transmission paths. This makes it possible to quickly measure transmission paths over the whole vehicle body.

One of the motivations for this work is the monitoring of sealing quality on production vehicles. Artificial seal breaches were introduced on the vehicle and a number of excitation signals were assessed to develop a method to detect and localise leakage noise sources.

The investigation and methodology demonstrate the potential for the use of reciprocal beamforming to detect acoustic transmission paths with a view to identifying errors that would impact a vehicle’s wind noise performance, for instance in a manufacturing environment. In addition, it also shows benefits in the use of a similar approach for detecting non-leakage transmission weaknesses, which has applications including the comparison of the isolation performance of various vehicles to external noises.
NVH Prediction and Real-Time Auralization for Virtually Assembled Vehicles: An Overview of the Technology
Authors: Bianciardi Fabio , Salamone Nicolò , Colangeli Claudio , Ortega Almirón Jesús , Verrecas Bart , Corbeels Patrick , Janssens Karl
Published: May 2023

The current trend toward hybrid and electric automotive powertrains increases the complexity of the vehicle development and integration work for the NVH engineers. For example, considering that the combustion noise is reduced or absent, secondary noise sources like drivetrain, auxiliary systems, road and wind noise become of relevance in terms of vehicle noise comfort. This trend combined with the shortening of vehicle development cycle, the increased number of vehicle variants and an increasingly competitive marketing landscape, force engineers to front-load their design choices to the early stages of the development process using advanced engineering analysis tools. In this context, innovative technologies such as Virtual Prototype Assembly (VPA) and NVH simulator provide the right support to the engineer’s needs when developing the vehicles of the future. The VPA technology enables target assembly noise predictions using the dynamic substructuring methodology starting from individual component models that are derived from simulation or test bench measurements. The NVH simulator, through a digital representation of the vehicle noise and vibration signature (NVH model), enables objective and subjective vehicle sound quality judgment while executing driving scenarios that have not been measured experimentally or fully simulated numerically. The NVH model can be based on data measured on an existing vehicle (top-down approach), on a VPA assembly of individual components characterized in laboratory or through simulation (bottom-up approach), or on a mix of both approaches. Moreover, engineers can, in an NVH simulator environment, interact with the virtual vehicle executing several driving scenarios in a realistic and interactive experience through a vehicle performance model connecting the running operation of the powertrain to the NVH model in a real-time co-simulation framework. In this paper the different technological building blocks will be described. Finally, industrial applications for road noise and electric powertrain noise will be presented and the elements of the methodological process will be validated.
Prediction of Minimum Sound Emission Requirements of an Electric/Hybrid Vehicle
Authors: Jayasheela Praveen , Calloni Massimiliano , Musser Chadwyck
Published: May 2023

Electric and Hybrid vehicles have standards for emitting enough noise to reduce danger and risk to pedestrians when operating at low speeds. Simulation can help to support development and deployment of these systems while avoiding a time-consuming, test-based approach to design these AVAS (Acoustic Vehicle Alerting System) warning systems. Traditionally, deterministic simulation methods such as Finite Element Method (FEM) and Boundary Element Method (BEM) are used at low frequencies and statistical, energy-based methods such as Statistical Energy Analysis (SEA) are used at high frequencies. The deterministic methods are accurate, but computationally inefficient, particularly when the frequency increases. SEA is computationally efficient but does not capture well the physics of exterior acoustic propagation. An alternative method commonly used in room acoustics, based on geometrical or ray acoustics, is “Ray Tracing” and can be used for sound field prediction. Ray Tracing generally estimates sound fields with an acceptable degree of accuracy through the full range of frequencies and can predict temporal and spatial distribution of sound fields with suitable accuracy for auralization. The image-source method is a ray acoustics method that guarantees finding all reflection paths up to a given order and can include diffraction effects.

In this paper, a systematic approach is discussed to evaluate the potential for Ray Tracing to predict sound fields for AVAS design. Ray Tracing models with different combinations of parameters are compared to a BEM model as a reference. An accelerated BEM method known as H-matrix is also included in the comparison as a reference and to evaluate the potential for accelerated BEM to be used when more accuracy than Ray Tracing is needed but standard BEM is challenging to use because of model size and frequency range. Some conclusions about these methods for this application and others, such as Pass-By Noise prediction, are presented.
Analysis and Optimization of Whine Noise of Light Bus E-axle System
Authors: Chengping Zhong , Guo Feng , Senhai Liu , Qingshuang Chen , Ping Xiao , Deng Xin , Xianzhong Yu
Published: May 2023

This paper investigates the problem of whine in the E-axle (Electric Drive Axle) system during acceleration of a light bus. The problem is identified as motor and reducer whine by the noise spectrum feature analysis method. Under the condition of ensuring motor performance and low cost, the motor whine is solved by optimizing the air tightness and sound insulation of the vehicle. Starting from gear microscopic shaping research, gear manufacturing and assembly process optimization was used to control gear whine. After testing and analysis, the means to effectively solve the E-axle system whine problem. The whine noise is optimized by about 8 dB (A). The results provide key technical support for the smooth production of the vehicle. It has certain guiding significance for the NVH (Noise, Vibration and Harshness) performance design and development of the E-axle system project.
Reducing the Probability of Error in Testing and Simulation
Authors: Reinhart Thomas
Published: May 2023

Simulation and testing are often done by different engineers in different departments of a company. This can lead to disconnects and unrealistic predictions, especially if the person doing simulations does not have an experimental background. On the other hand, experimental results can also include errors that result in misleading answers. It is important for the engineer doing either testing or simulation to have a good understanding for what results are plausible and what results might be suspect. This paper will provide examples where error crept into testing or simulation that could have been caught and corrected early if a good feel for “reasonable” results had been in place. The importance of understanding how a software package is analyzing the data will be explained, since settings buried deep within a menu structure can drive misleading results. The paper will also make the case for simulation engineers to be provided with some experimental background, so that they have a better physical understanding of the structures or components being simulated. The ideal case is where the same person is responsible for both simulation and experimental validation.
Development Strategies for Creating Quiet Vehicles: Insights from a 35 -Year Veteran
Authors: Wentzel Richard
Published: May 2023

From the early 1980’s through 2015, the engineering community has witnessed dramatic changes in the technology for mitigating sound in vehicles. Throughout these years, vehicle noise, vibration, and harshness (NVH) engineers were skilled and talented in testing vehicles, and at conducting laboratory studies of materials and trim-insulator components. This paper surveys a wide variety of processes that NVH automotive engineers use to develop trim-insulator packages which are effective in reducing cab-interior noise while being esthetically appealing. Analytical models are used to cascade overall cab-interior sound pressure level (SPL) targets to trim-insulator performance targets. This paper also reviews how sound absorption is employed to reduce cab-interior SPL. Acoustical material laboratory tests are briefly described along with the role they play in selecting trim-insulator products for vehicles. And finally, body shell acoustical isolation is examined, and a mathematical relationship is derived between cab air-leakage and acoustical degradation.
System Engineering Approach to NVH Attribute Management for Transport Refrigeration
Authors: Clark Adam , Stinson Matt , Wang Jingdou
Published: May 2023

The transport refrigeration market is in a transformation like what automotive experienced over the last 20 years using a systems engineering approach complemented with complex attribute optimization to manage product development. With a heavy push for electrification due to government regulations, sustainability initiatives, and designing the products to align with the OEMs electrified platforms Noise, Vibration, and Harshness (NVH) must be considered. Understanding the above along with refined customer expectations the NVH attribute has become even more critical to product quality. This paper showcases the acoustic design of an electrified system using a system engineering approach to achieve unit level targets deploying a system engineering V-model philosophy. Unit level requirements were set and flowed down to component level requirements. A 1D acoustic tool was developed leveraging classic physical acoustics theory and legacy product knowledge to target set what was possible for various architecture possibilities and rapidly iterate on design choice implications and complete attribute trade off analysis. Component and unit level testing was utilized to refine model parameters and develop a continuous surface to interpolate and extrapolate system performance. Model verification and validation will be discussed along with final unit qualification to meet requirements. Further work on unit noise optimization using the system model will be covered along with future work for model refinement.
Machine-Learning-Based Modelling of Electric Powertrain Noise Control Treatments
Authors: Kocsis Attila , Jacqmot Jonathan
Published: May 2023

Encapsulation of electric powertrains is a booming topic with the electrification of vehicles. It is an efficient way of reducing noise radiated by the machines even in later stages of the design and without altering the electromagnetic performance. However, it is still difficult to define the best possible treatment. The locations, thicknesses and material compositions need to be optimized within given constraints to reach maximum noise reduction while keeping added mass and cost at minimum. In this paper, a methodology to design the encapsulation based on numerical vibro-acoustic simulations is presented. In a first step, the covered areas are identified through post-processing of a finite element acoustic radiation model of the bare powertrain. In a second step, a design of experiment is performed to assess the influence of various cover parameters on the acoustic radiation results. This second step can be hugely computationally expensive as the number of required virtual experiments increases exponentially with the number of treated regions and parameters for each treated region. In this chapter, we present a physics-based reduced-order model to overcome this difficulty and do design of experiments in a much more affordable manner. It is then enriched with machine learning to provide finer tuning of the treatment definition. This would allow the final designer to iterate between treatment strategy in the matter of seconds, paving the road for an advanced optimization algorithm. The accuracy of the presented models is detailed.
Tribodynamics of Spiral Bevel Gears under Mixed Elastohydrodynamic Lubrication
Authors: Conjeevaram Gopalakrishnan Srikumar , Wang Yawen , Lim Teik C.
Published: May 2023

Spiral bevel gears are commonly used in heavy-duty trucks and buses. An integrated dynamic model of the spiral bevel gears with mixed elastohydrodynamic lubrication is proposed in this study. First, loaded tooth contact analysis was performed to evaluate the kinematic parameters and calculate the mesh force variation for one mesh cycle. These kinematic quantities are used in the mixed elastohydrodynamic lubrication (EHL) calculation to determine the EHL parameters such as pressure, film thickness, and shear distribution considering the surface roughness profile of the spiral bevel gears. Then, the EHL pressure and film thickness are used in the calculation of the coefficient of friction, damping, and oil film elastohydrodynamic lubrication stiffness. Last, these tribological parameters are used in the dynamic calculation of the spiral bevel gears. The calculated tribodynamic response of the spiral bevel gears are compared for different dynamic models and the influence of lubrication on the gear dynamic responses is discussed.
Effect of Compound Asymmetric Gearing on Dynamics of Gear Transmission
Authors: Wright Ned , Shi Zhenghong , Andres Greg , Shupe Andy , Jasper Levi , Pandav Ranjeet , Nakandakari Marcelo
Published: May 2023

The fast-growing automotive industry and rapid development of new E-drive technology nowadays brings about higher gear design requirements. E-motor applications challenge gear performance due to their higher load and speed levels compared to traditional internal combustion engines (ICE). The advantages of using asymmetric gears include lower stress, higher efficiency, better bending and contact strength, increased durability, etc. However, asymmetric gear dynamics are not well understood or analyzed. This paper performs extensive study on the effect of asymmetric gears on NVH performance of compound gear transmissions. The parametric study covers different combinations of pressure angles and root fillet settings on the drive and coast sides of the gear. The analysis is focused on the sensitivity of gear transmission error (TE) towards different symmetric and asymmetric gear designs. On the system level, the influence of asymmetric gearing on the line-of-action (LOA) and effective mesh stiffness is investigated and compared with symmetric design. Finally, this study aims at providing an effective method of asymmetric gear design optimization for automotive applications in view of noise and vibration characteristics.
Root Cause Analysis of Limited Slip Differential Noise Vibration Harshness
Authors: Sarkar Subrata , Samuelson Eric , Allen Jordan , Spiekermann Ryan
Published: May 2023

The primary objective of this research was to identify the root cause of limited slip differential (LSD) NVH. The study examined the significance of different oils and additives that make up the lubrication mix in the axle. The impacts of gear marking compound type, friction modifier type, gear marking compound level, friction modifier level, reaction plate surface finish roughness, and friction material type were studied using Taguchi's Design of Experiment. Eaton's Vertical Friction Tester (VFT), a sub-system level test stand, was used to measure the performance characteristics of the clutch pack and oil mix. Sequential approximation and cumulative analysis methodologies were used to analyze test data where NVH was beyond the measurement capacity of the test stand. The DOE analysis showed that the type of gear marking compound used to set the ring gear mesh during axle build had the most significant influence on NVH levels.
Contributiuon Analysis for Ride Comfort Evaluations
Authors: Thom Brian , Blanco David , Caltagirone Elizabeth
Published: May 2023

In the current changing noise, vibration, and harshness (NVH) landscape, there is an increased amount of collaboration between NVH engineers and other attribute engineering groups to solve complex issues. One of these complex issues is ride comfort. An increasing amount of ride comfort development is happening between NVH and ride and handling (R&H) engineers. To apply a NVH process to a R&H phenomenon, it is important to ensure that both the transducer selection as well as analysis method will be applicable over the frequency range of interest. Specifically for ride comfort development, the validation of the use of strain gauges and accelerometers along with source path contribution analysis, or transfer path analysis, is key to bridging the gap between NVH and R&H.

A source path contribution, also known as a transfer path analysis, model can be utilized to understand the contributions from various sources, both structural and acoustic, to a given set of receivers in the interior of a vehicle. The methodology can be applied to gain insight into the primary sources and contribution paths. For ride comfort evaluations, this could identify the key input forces and body sensitivity characteristics through suspension and drivetrain components that are most affecting the customer experience. Once identified, the contributions from these sources can be utilized within NVH and R&H simulators to experience the measured condition subjectively, as well as allow for virtual part swaps and modifications to either input forces or body structural responses.