ORCID Profile
0000-0002-5242-9162
Current Organisation
RMIT University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Springer Science and Business Media LLC
Date: 03-2023
DOI: 10.1007/S13272-023-00655-0
Abstract: The eVTOL industry is a rapidly growing mass market expected to start in 2024. eVTOL compete, caused by their predicted missions, with ground-based transportation modes, including mainly passenger cars. Therefore, the automotive and classical aircraft design process is reviewed and compared to highlight advantages for eVTOL development. A special focus is on ergonomic comfort and safety. The need for further investigation of eVTOL’s crashworthiness is outlined by, first, specifying the relevance of passive safety via accident statistics and customer perception analysis second, comparing the current state of regulation and certification and third, discussing the advantages of integral safety and applying the automotive safety approach for eVTOL development. Integral safety links active and passive safety, while the automotive safety approach means implementing standardized mandatory full-vehicle crash tests for future eVTOL. Subsequently, possible crash impact conditions are analyzed, and three full-vehicle crash load cases are presented.
Publisher: Springer International Publishing
Date: 12-06-2018
Publisher: Inderscience Publishers
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 10-06-2015
Publisher: Elsevier BV
Date: 2017
Publisher: International World Wide Web Conferences Steering Committee
Date: 18-05-2015
Publisher: Springer International Publishing
Date: 2016
Publisher: Springer International Publishing
Date: 2016
Publisher: Acoustical Society of America (ASA)
Date: 07-2021
DOI: 10.1121/10.0005201
Abstract: Fault identification using the emitted mechanical noise is becoming an attractive field of research in a variety of industries. It is essential to rank acoustic feature integration functions on their efficiency to classify different types of sound for conducting a fault diagnosis. The Mel frequency cepstral coefficient (MFCC) method was used to obtain various acoustic feature sets in the current study. MFCCs represent the audio signal power spectrum and capture the timbral information of sounds. The objective of this study is to introduce a method for the selection of statistical indicators to integrate the MFCC feature sets. Two purpose-built audio datasets for squeak and rattle were created for the study. Data were collected experimentally to investigate the feature sets of 256 recordings from 8 different rattle classes and 144 recordings from 12 different squeak classes. The support vector machine method was used to evaluate the classifier accuracy with in idual feature sets. The outcome of this study shows the best performing statistical feature sets for the squeak and rattle audio datasets. The method discussed in this pilot study is to be adapted to the development of a vehicle faulty sound recognition algorithm.
Publisher: IEEE
Date: 2013
Publisher: ASME International
Date: 08-2003
DOI: 10.1115/1.1589777
Abstract: Although many studies exist concerning the influence of seat vibration on the head in the seated human body, the dynamic response of the head-neck complex (HNC) to the trunk vibration has not been well investigated. Little quantitative knowledge exists about viscoelastic parameters of the neck. In this study, the dynamics of the HNC is identified when it is exposed to the trunk horizontal (fore-and-aft) vibration. The frequency response functions between the HNC angular velocity and the trunk horizontal acceleration, corresponding to four volunteers, are obtained in the frequency range of 0.5 Hz to 10 Hz. A fourth-order mathematical model, derived by considering a double-inverted-pendulum model for the HNC, is designed to simulate the dynamic response of the HNC to the trunk horizontal vibration. The frequency domain identification method is used to determine the coefficients of the mathematical model of the HNC. Good agreement has been obtained between experimental and simulation results. This indicates that the system, similar to the designed fourth-order model, has mainly two resonance frequencies. The viscoelastic parameters of the neck, including the spring and d ing coefficients, are then obtained by use of the optimization method.
Publisher: Informa UK Limited
Date: 29-09-2020
Publisher: Japan Society of Mechanical Engineers
Date: 2003
DOI: 10.1299/JSMEC.46.116
Publisher: SAE International
Date: 04-2011
DOI: 10.4271/2011-01-0501
Publisher: SAE International
Date: 12-04-2011
DOI: 10.4271/2011-01-0504
Publisher: Informa UK Limited
Date: 20-05-2016
DOI: 10.1080/00140139.2016.1170891
Abstract: Although much research has been done in developing the current ISO 2631-1 (1997) standard method for assessment seat vibration comfort, little consideration has been given to the influence of vehicle seat structural dynamics on comfort assessment. Previous research has shown that there are inconsistencies between standard methods and subjective evaluation of comfort at around vehicle seat twisting resonant frequencies. This study reports the frequency-weighted r.m.s. accelerations in [Formula: see text], [Formula: see text] and [Formula: see text] axes and the total vibration (point vibration total value) at five locations on seatback surface at around vehicle seat twisting resonant frequencies. The results show that the vibration measured at the centre of seatback surface, suggested by current ISO 2631-1 (1997), at around twisting resonant frequencies was the least for all tested vehicle seats. The greatest point vibration total value on the seatback surface varies among vehicle seats. The variations in vibration measured at different locations on seatback surface at around twisting resonant frequencies were sufficiently great that might affect the comfort assessment of vehicle seat.Practitioner Summary: The influence of vehicle seat structural dynamics has not been considered in current ISO 2631-1 (1997). The results of this study show that the vibration measures on seatback surface at around vehicle seat twisting resonant frequency depends on vehicle seats and dominate at the top or the bottom of seatback but not at the centre.
Publisher: Springer International Publishing
Date: 2015
Publisher: SAE International
Date: 13-06-2018
DOI: 10.4271/2018-01-1479
Publisher: Springer International Publishing
Date: 2015
Publisher: SAE International
Date: 10-03-2015
DOI: 10.4271/2015-01-0046
Publisher: SAE International
Date: 14-04-2015
DOI: 10.4271/2015-01-1132
Publisher: Inderscience Publishers
Date: 2014
Publisher: SAGE Publications
Date: 12-04-2013
Abstract: An ideal engine mount should provide a dual behavior. It needs to be soft to reduce the transmitted force, and to be hard to limit the relative displacement. The constant parameter linear mounts are unable to provide a good isolation when the excitation frequency is variable. Hydraulic engine mounts were invented as smart isolators to passively produce a soft isolator at low litude and a hard isolator at high litude. Having a dual behavior puts the mounts in the domain of nonlinear systems which in turn causes many new phenomena which have never appeared in linear analysis. The dual behavior hydraulic engine mounts were introduced around 1980 and passed through many analytic and technical improvements. This article will review these improvements up to 2012 and discusses the technical problems and methods of remedy.
Publisher: Springer Berlin Heidelberg
Date: 07-11-2012
Publisher: Japan Society of Mechanical Engineers
Date: 2009
DOI: 10.1299/JBSE.4.265
Publisher: Elsevier BV
Date: 03-2018
Publisher: SAE International
Date: 27-09-2016
DOI: 10.4271/2016-01-8030
Publisher: Springer International Publishing
Date: 14-10-2014
Publisher: Elsevier BV
Date: 06-2017
Publisher: Inderscience Publishers
Date: 2014
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.APERGO.2019.102929
Abstract: Occupant discomfort, induced by vibration transmitted through a vehicle seat, can be evaluated by measuring vibration on the contact interface between the occupant and seat. In the previous study (Ittianuwat et al., 2016), measuring five contact points of the back-backrest, including centre point (ISO 2631-1), was considered as an important factor for assessing occupant comfort in frequencies where seat structure resonances occur. To enhance occupant vibration comfort in the early seat design stage, predicting the dynamic response of the coupled human-seat system on various contact locations is necessary. In this study, a low order seated human body Finite Element (FE) model was developed for predicting vibration transmissibility of the human-seat system in frequencies up to 30 Hz. Throughout the optimization process, the parameters of the model were obtained by comparing measured transmissibilities of the occupied vehicle seat system. The human-seat system vibration modes were also compared and verified with measured data by calculating MAC (Modal Assurance Criterion). The results showed that two human body vibration modes coupled with foam were observed below 10 Hz, and two coupled human and seat structure fore-aft modes were observed at around 20.1 Hz and 21.9 Hz. Fore-aft transmissibility of the model at various locations of contact provided reasonable correlation with the measured data. The developed low order human model enables the prediction of the fore-aft transmissibility on various back-backrest contact locations up to 30 Hz. This showed the capability of improving occupant's vibration comfort by predicting transmissibilities of the human-seat system in the early stage of developing a new vehicle seat.
Publisher: Informa UK Limited
Date: 21-11-2016
DOI: 10.1080/00140139.2016.1252063
Abstract: Characterising the coupling between the occupant and vehicle seat is necessary to understand the transmission of vehicle seat vibration to the human body. In this study, the vibration characteristics of the human body coupled with a vehicle seat were identified in frequencies up to 100 Hz. Transmissibilities of three volunteers seated on two different vehicle seats were measured under multi-axial random vibration excitation. The results revealed that the human-seat system vibration was dominated by the human body and foam below 10 Hz. Major coupling between the human body and the vehicle seat-structure was observed in the frequency range of 10-60 Hz. There was local coupling of the system dominated by local resonances of seat frame and seat surface above 60 Hz. Moreover, the transmissibility measured on the seat surface between the human and seat foam is suggested to be a good method of capturing human-seat system resonances rather than that measured on the human body in high frequencies above 10 Hz.Practitioner Summary: The coupling characteristics of the combined human body and vehicle seat system has not yet been fully understood in frequencies of 0.5-100 Hz. This study shows the human-seat system has distinctive dynamic coupling characteristics in three different frequency regions: below 10 Hz, 10-60 Hz, and above 60 Hz.
Publisher: Elsevier BV
Date: 07-2017
Publisher: Springer New York
Date: 29-07-2013
Publisher: SAE International
Date: 10-03-2015
DOI: 10.4271/2015-01-0012
Publisher: Elsevier BV
Date: 05-2016
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 10-2016
Publisher: Springer New York
Date: 12-2011
Publisher: Elsevier BV
Date: 09-2015
Publisher: Inderscience Publishers
Date: 2016
Publisher: Springer International Publishing
Date: 28-05-2017
Publisher: Elsevier BV
Date: 02-2013
Publisher: Springer Berlin Heidelberg
Date: 07-11-2012
Publisher: Inderscience Publishers
Date: 2016
Publisher: Springer International Publishing
Date: 2014
Publisher: Elsevier BV
Date: 03-2015
Publisher: SAGE Publications
Date: 18-06-2020
Abstract: Although the concept modeling method has already been proposed in the literature, there is still very limited knowledge about the validation and the application of this method for vehicle body design. This paper substantially increases this limited knowledge by developing a concept model for predicting and optimizing the structural dynamics of a vehicle body-in-white and validating this concept model against a detailed finite element model. The geometry and parameters of the concept model are extracted from its detailed finite element model. The major members and panels of the detailed finite element model are replaced by their equivalent beam and shell elements models. The joints of the concept model are represented by stiffness and mass matrices extracted from the detailed finite element model using the Guyan Reduction Method. The developed concept model is validated by comparing its structural dynamics, including the resonant frequencies and the vibration mode shapes, with the original detailed finite element model and the experimental results. The simplicity and small size of the concept model enable it to easily enhance the structural dynamics of the body-in-white by optimizing the cross-sections of the load-carrying members of the structure. The optimization in this case increased the resonant frequencies of the body-in-white while reducing the total mass by about 6 kg. The results prove that the concept modeling method can significantly enhance the body-in-white structural dynamics by reducing the complexity of the model and allowing the focus for the optimization to be on the main members of the structure at the development stage when the final design parameters are not well known and have not been fixed.
Publisher: Springer New York
Date: 29-07-2013
Publisher: Informa UK Limited
Date: 2014
DOI: 10.1080/10803548.2014.11077060
Abstract: A large number of independent and interacting factors affect seating comfort such as seat shape, stability, lumbar support and seat height. Although many subjective comfort studies have been conducted, few of them considered seating comfort from its subassembly level. This paper analyzed the automotive seat cushion designed with geared four-bar linkage for the seat height adjustment. The operation torque and lift distance of this mechanism was investigated as 2 major comfort factors. Ten cushions with this kind of design in the market were compared and assessed.
Publisher: ASMEDC
Date: 2010
Abstract: Most of the researches about vehicle ride comfort and effects of the car body vibration on vehicle occupant had little or no focus on the structural modal characteristics of the vehicle body while these characteristics can have large effects on the transmission of the vibration to the vehicle occupant. One of the issues of the automotive ride comfort is related to the transmission of the vibration from the rear suspension to the rear seat mounting and therefore the seat and the vehicle occupant. Since such vibration are mainly caused by the rear body structure torsion mode, more care is required to predict the characteristics of this torsion mode in early design phase of the car. When the predecessor platform is resized for using a new car, it is sometimes necessary to extend the rear overhangs of the car. This research shows that the length of rear overhang may have a large effect on the torsion mode of the body and therefore on the transmission of the vibration from the road or rear suspension (shock absorbers) to the rear seat mountings. When a same platform is used for two similar models with different lengths of rear overhangs, the rear seat vibration level can considerably be different for these two similar models. An automotive CAE concept beam model, here, is used to investigate the effects of rear overhang on the rear seat vibration and comfort level. CAE beam concept models for the car body are important tools are used to predict and optimize the structural dynamics, in early design phase where there is no enough detailed design data. Here, the results show that by extending the rear overhang, the dynamic stiffness of the rear/overhang bending decreases and this may considerably aggravates the transmission of the vibration to the seat.
Publisher: Springer Science and Business Media LLC
Date: 05-2004
DOI: 10.1007/S00422-004-0489-Z
Abstract: A method is proposed for identifying the head-neck complex (HNC) in the seated human body when it is exposed to the trunk horizontal (fore-and-aft) vibration. It is assumed that the HNC only has the anteroposterior (flexion/extension) motion in the sagittal plane. An electrohydraulic vibrator is used as a source of vibration. To generate the trunk horizontal vibration, the trunk of the seated subject is fixed to the seatback. The subjects are exposed to the random vibration at a magnitude of 1.60 ms(-2) rms (root-mean-square) for 50 s. The coherence and frequency response function are then obtained in the frequency range 0.5-3 Hz. The results show that the HNC behavior is quasilinear with a resonance frequency between 1 and 1.4 Hz. Accordingly, a two-dimensional single-inverted pendulum is considered as a model for the HNC. The frequency domain identification method is then used to estimate the unknown parameters, including the HNC viscoelastic and inertia parameters. The model is examined in a time domain using the random vibration. Good agreement is obtained between experimental and simulation results, indicating the reliability of the proposed method.
Publisher: IEEE
Date: 03-2016
Publisher: ACM
Date: 14-11-2016
Publisher: SAE International
Date: 10-03-2015
DOI: 10.4271/2015-01-0067
Publisher: Elsevier BV
Date: 2012
Publisher: Springer International Publishing
Date: 2018
Publisher: SAGE Publications
Date: 17-10-2017
Abstract: When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomenon decreases lateral force, limits tyre performance and eventually reduces the vehicle lateral grip capacity. This paper proposes a strategy for varying caster in the front suspension, thereby altering the wheel camber to counteract this outward inclination. The homogeneous transformation was utilised to develop the road steering wheel kinematics which includes the wheel camber with respect to the ground during a cornering manoeuvre. A variable caster scheme was proposed based on the kinematic analysis of the camber. A rollable vehicle model, along with a camber-included tyre force model, was constructed. MATLAB/Simulink was used to simulate the dynamic behaviour of the vehicle with and without the variable caster scheme. The results from step steer, r steer, and sinusoidal steer inputs simulations show that the outward leaning phenomenon of the steering wheels equipped with the variable caster, is reduced significantly. The corresponding lateral acceleration and yaw rate increase without compromising other handling characteristics. The actively controlled car, therefore, provides better lateral stability compared to the passive car. The tyre kinematic model and the vehicle dynamic model were validated using multibody and experimental data.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 03-2017
Publisher: Informa UK Limited
Date: 14-07-2014
DOI: 10.1080/00140139.2014.934300
Abstract: The ISO 2631-1 ( 1997 ) provides methodologies for assessment of the seated human body comfort in response to vibrations. The standard covers various conditions such as frequency content, direction and location of the transmission of the vibration to the human body. However, the effects of seat structural dynamics mode shapes and corresponding resonances have not been discussed. This study provides important knowledge about the effects of vehicle seat structural vibration modes on discomfort assessment. The occupied seat resonant frequencies and corresponding vibration modes were measured and comfort test was carried out based on the paired comparison test method. The results show that the ISO 2631-1 ( 1997 ) method significantly underestimates the vibration discomfort level around the occupied seat twisting resonant frequencies. This underestimation is mainly due to the ISO suggested location of the accelerometer pad on the seatback. The centre of the seatback is a nodal point at the seat twisting mode. Therefore, it underestimates the total vibration transferred to the occupant body from the seatback. The effects of the vehicle seat structural dynamics have not been discussed in the human body vibration ISO . The results of this research show that the current measurement method suggested by ISO 2631-1 (1997) can significantly underestimate the vibration discomfort level at around the seat structural vibration mode.
Publisher: Elsevier BV
Date: 11-2015
No related grants have been discovered for Mohammad Fard.