Mohammad Fard

Mohammad Fard
RMIT University | RMIT · Department of Mechanical Engineering and Manufacturing

About

101
Publications
66,144
Reads
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1,078
Citations
Citations since 2016
54 Research Items
929 Citations
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
2016201720182019202020212022050100150
Introduction
Skills and Expertise

Publications

Publications (101)
Article
Sound absorption coefficient (SAC) measurements in a reverberation room may produce different values for different sample sizes of the same material because of the edge effect which depends on the geometrical properties of the sample. In this paper, the theory of the maximum SAC for a given size and shape of sample is extended to non-locally reacti...
Conference Paper
In the automotive industry, sound-absorbing materials are used to control vehicle noise and improve the quality of the acoustic environment of a vehicle cabin. With the recent development of the automotive industry, engineers, designers, or material manufacturers are required to design vehicle interior systems that are suitable for new types of v...
Conference Paper
In this paper, Electroencephalogram (EEG) based driving fatigue detection by using the Topological Data Analysis (TDA) was presented. The experimental obtained EEG activity signal was marked by combining the KSS (Karolinska Sleepiness Scale) results and recorded facial video for different participants, to form a binary data set of driving fatigue s...
Conference Paper
In this paper, the acoustic properties of multilayer sound absorbers were optimized by using the genetic algorithm (GA). The multilayer sound absorber was combined with a porous material layer attached behind a micro-perforated panel absorber (MPPA) layer, and backed by an airgap layer. The analytical model was constructed by utilizing the Transfer...
Article
Full-text available
Introduction: Whole-body vibration has direct impacts on driver vigilance by increasing physical and cognitive stress on the driver, which leads to drowsiness, fatigue and road traffic accidents. Although sleep deprivation, sleep apnoea and alcohol consumption can also lead to driver drowsiness, exposure to steady vibration is the factor most readi...
Article
Measuring the random incidence sound absorption coefficient (SAC) of porous materials is costly and requires a full-size reverberation room. This paper shows that the predictions from impedance tube measurement and the empirical method have reasonable accuracy for the determination of the random incidence SAC above 400 Hz. It also shows that the me...
Article
Quarter-car model is examined here from a new viewpoint to consider tyre-road separation. A nonlinear model is formulated using nondimensionalisation methods which would incorporate the tyre-road discontinuities to minimise the number of parameters and generalise the analysis. The investigation of the frequency responses and fraction of the separat...
Conference Paper
Full-text available
The Discomfort Criterion (DiC) is defined as a new vehicle ride comfort indicator based on several real-life driving scenarios and realistic driving assumptions. The criterion scrutinizes the feeling of discomfort of an occupant during a road trip due to the roughness of road surface, in accordance with the ISO 2631 (Mechanical vibration and shock-...
Chapter
Full-text available
Research on vehicle dynamics usually works on the assumption that vehicle is bilaterally symmetrical. In practice, however, cars may have laterally asymmetrical characteristics due to different reasons. This investigation looks into how the lateral asymmetry affects the dynamic behavior of a steering vehicle. In order to do so, an unconventional pl...
Article
Full-text available
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 obt...
Chapter
Drowsiness is one of the major hazards contributing to transportation accidents. This project aims to investigate the effects of the low-frequency vibration on vehicle driver drowsiness. Heart rate variability (HRV) and the subjective sleepiness scale are used to measure the alertness/drowsiness level. A random vibration signal with a limited band...
Article
Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining...
Chapter
Prediction of vehicle vibration discomfort is still challenging. This is due to the non-linear dynamics of the human body and the seat foam as well as the complex coupling between the vehicle body and the seat. In this chapter, a hybrid modeling approach is developed by combining the vibration transfer matrices of sub-systems, some obtained from ph...
Article
A novel optimization technique was implemented to investigate the effects of vibrations on comfort of occupants to maintain oscillations in an acceptable zone in accordance with the International Organization for Standardization 2631 standard. In this regard, a newly introduced comfort indicator was defined as discomfort criterion (DiC). The effect...
Article
Full-text available
This paper describes a new design method that was developed to achieve an optimal design method for weight reduction of a bell crank, sourced from a Louis Christen Road Racing F1 Sidecar. The method involved reverse engineering to produce a 3D model of the mechanical part. The 3D bell crank model was converted to a finite element (FE) model to char...
Article
Full-text available
The frequency response data of human body vibration are often used for standardisation, design of transport vehicles and occupational health and safety measures. This article shows that the commonly used methods of averaging frequency response spectra, such as arithmetic averaging in the complex or magnitude domain and median averaging, are not as...
Article
In this paper, a simplified car air cavity model for predicting the influence of an interior trim material on the cabin interior sound pressure level (SPL) was presented. This work studies a rigid-walled car cabin model with one flexible wall. The interior trim material (a porous sound-absorbing material) was mounted in between the enclosed car air...
Article
In this article, an artificial neural network is proposed to classify short audio sequences of squeak and rattle (S&R) noises. The aim of the classification is to see how accurately the trained classifier can recognize different types of S&R sounds. Having a high accuracy model that can recognize audible S&R noises could help to build an automatic...
Article
Full-text available
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 ve...
Article
This article investigates whether the robust landmark-based audio fingerprinting method created for recognizing music can be applied to identify squeak and rattle (S&R) types of sounds. The identification is performed by matching a query audio sample to the perceptually closest audio sample that is stored in a pre-developed database of S&R audio so...
Article
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...
Conference Paper
The traditional formula for the mass-air-mass resonance frequency of a cavity wall works well for walls without a structural connection between their two wall leaves or for walls whose wall leaves are connected by highly resilient structural connections such as steel studs manufactured from thin 25 gauge steel sheet. However, for cavity walls whose...
Article
Full-text available
The flexion-extension motion of the head-neck complex (HNC) in the trunk horizontal (fore-and-aft) vibration was investigated. It was assumed that the motion of the HNC only occurs in mid-sagittal plane. An electro-hydraulic vibrator was used as a source of vibration. The input acceleration and HNC angular velocity were measured whereas the trunk o...
Chapter
Full-text available
The nonlinearities in human body dynamics is discussed by focusing on the intrinsic (passive) and reflexive (active) dynamics of head-neck complex (HNC). An experiment is first designed to measure the passive responses of HNC to horizontal fore-and-after vibration. The intrinsic frequency response function between the HNC angular velocity and the t...
Article
Full-text available
N oise, vibration, and harshness (NVH) attribute is needed to be included in the vehicle structure design since improving the NVH characteristics enhances the ride quality experienced by the occupants. In this regard, an efficient method was proposed to investigate the structural dynamic response of an automotive body considering low-frequency NVH...
Article
Full-text available
We investigated the effects of low frequency whole body vibration on heart rate variability (HRV), a measure of autonomic nervous system activation that differentiates between stress and drowsiness. Fifteen participants underwent two simulated driving tasks for 60 minutes each: one involved whole-body 4-7 Hz vibration delivered through the car seat...
Conference Paper
By modelling a four-wheel vehicle as a bicycle, it has been suggested (Olley 1934) that if the radius of gyration, r, in pitch is equal to the multiplication of the distance from the center of gravity of the front, a, and rear, b, wheels of the car (\( r^{2} = a \cdot b \)), the bounce center of the vehicle will be located at one spring and the pit...
Article
Full-text available
Accurate estimation of tooth-root stress has been of great interest to researchers and engineers to prevent catastrophic damage of gear transmission system. However, analytical models in AGMA standard are not precise and FEM are mostly focused on the analysis of spur gear pairs. As a result, very little research has been conducted to investigate th...
Article
The purpose of this paper is to show the effect of acceleration -variable forward velocity-, on the steady-state and transient responses of turning vehicles and the resulted path of motion of the vehicle. Comparing the responses of the vehicle will be used to prove that there is a negligible difference between the steady-state and transient center...
Article
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 inclinat...
Conference Paper
This paper presents a rigid walled car cabin model to predict the acoustic effects of vehicle interior trim materials. The car cavity is made of a rigid walled enclosure system with one flexible wall on the front firewall position, where the interior trim materials are applied to the inner surface of the front firewall to modify the coupling betwee...
Article
The sound absorption coefficient of a micro-perforated panel (MPP) backed by a porous sound absorbing material is investigated in this paper. The feasibility to fabricate MPP acoustic absorber using 3D printing technology is presented. The test specimens are made of polymer material, and they are printed with different perforation ratios. A porous...
Article
This paper investigates the acoustic absorption capability of a multilayer micro-perforated panel absorber (MPPA) whose front layer is produced by additive manufacturing. The MPPA layers are printed using a polymer material, where the different hole spacing is used to create different perforation ratios. The sound absorption coefficients are experi...
Article
Although much research has been devoted to the characterization of the effects of whole-body vibration on seated occupants' comfort, drowsiness induced by vibration has received less attention to date. There are also little validated measurement methods available to quantify whole body vibration-induced drowsiness. Here, the effects of vibration on...
Article
This paper presents the kinematics of a steerable tyre with a variable caster. It serves as a first step towards developing the theory of variable caster steering in which wheel camber is controlled by the variable caster. The homogeneous transformation was utilised as a tool to develop the kinematics. The wheel camber, extracted from the kinematic...
Article
As long as a tire steers about a titled kingpin pivot, the point coming in contact with the road moves along its perimeter. This movement affects the determination of kingpin moments caused by the tire forces, especially for large steering angles. The movement, however, has been neglected in the literature on the steerable-tire-kinematics-related t...
Article
The effect of acceleration - variable forward velocity, have been investigated on the steady-state and transient responses of turning vehicles and the resulted path of motion of the vehicle. Comparing the two mentioned responses of the vehicle could be used to prove that there is a negligible difference between the steady-state and transient centre...
Article
Full-text available
The rubber materials that act as the main spring of a hydraulic mount obey nonlinear constitutive relationships. In addition to the material nonlinearity, further nonlinearities may be introduced by mount geometry, turbulent fluid behavior, boundary conditions, temperature, decoupler action, and hysteretic behavior. While all influence the behavior...
Article
Estimation of time-varying meshing stiffness (TVMS) is a vital process as it is one of the primary sources of vibration and noise. There are two ways to evaluate the TVMS, the analytical method (AM) and the finite element method (FEM). Owing to the complex geometries and the use of empirical values, analytical model is not precise to perform the ex...
Article
This paper predicts the acoustic properties of the porous sound-absorbing material in a box cavity by conducting a finite element method (FEM) analysis, and it verifies the estimated acoustic properties using an appropriate experimental method. The cavity is a rectangular box with five rigid walls and one flexible wall which is an aluminium plate....
Article
Full-text available
Characterizing 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 differ...
Conference Paper
This paper predicts the acoustic properties of the porous material in a car cabin model by using an appropriate experimental method, and it verifies the estimated acoustic properties by conducting the FEM (Finite Element Method) analysis. A simplified vibro-acoustic system imitating a car cabin is set up. The car cabin is made of six rigid walls, a...
Chapter
In a car crash, the higher level of energy absorption in the frontal structures leads to less transferred energy to the passengers and hence a safer car. S-shaped front rails, also known as S-rails, are one of the main structural elements and energy absorbers in a car body. Energy absorption in the S-rails happens through local buckling. In order t...
Chapter
Full-text available
A variation in the camber of an automotive wheel is desired to compensate a side-slip force reduction owing to transversely normal load shift when the car is cornering. The camber of a steered wheel can be varied by adjusting caster or/and lean angles which are the representations of steering axis orientation. Thus, adjustable camber can be created...
Article
In a vehicular crash, a higher level of energy absorption in the frontal structures of the vehicle leads to less transferred energy to the passengers and less possibility for injury. S-shaped front rails, also known as S-rails, are one of the main structural elements and energy absorbers in the body of a vehicle. To improve the safety of passengers...
Article
Full-text available
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 eva...
Article
Full-text available
Although much is known about human body vibration discomfort, there is little research data on the effects of vibration on vehicle occupant drowsiness. A laboratory experimental setup has been developed. Vibration was applied to the volunteers sitting on the vehicle seat mounted on the vibration platform. Seated volunteers were exposed to a Gaussia...
Article
Full-text available
The characterisation of the occupied vehicle seat structural dynamics is still challenging owing to the complex and nonlinear dynamic behaviour of the human body. The human body has significant influences on the occupied vehicle seat structural dynamics. In this paper, the structural dynamics of the unoccupied seat, occupied seat in lean-on posture...
Article
This paper predicts the acoustic properties of the porous sound-absorbing material in a box cavity by conducting a finite element method (FEM) analysis, and it verifies the estimated acoustic properties using an appropriate experimental method. The cavity is a rectangular box with five rigid walls and one flexible wall which is an aluminium plate....
Article
There are two main shortcomings in existing methods for finding steering angles for the application of autodriver algorithm. First, the fact that kinematic steering angles are not accurate enough. Second, in many cases the equation of the road is so complicated that makes it impossible to solve the equations of motion of the vehicle. The proximity...
Article
This article aims at identifying the possible cause of the detachment between a worm and its coupled motor shaft. Investigation includes several characterization techniques such as visual observation, mechanical testing and metallographic examinations. Reasons of the failure are identified as design errors. Design parameters and manufacturing proce...
Conference Paper
Full-text available
The ISO standard assessment of vehicle seat vibrations to comfort is currently unclear, there is still inconsistencies between objective measures of seat vibration made using standard methods and subjective evaluation of comfort. This study aims to investigate the effect of vehicle seat structural dynamics on frequency-weighted r.m.s. accelerations...
Conference Paper
Porous materials are usually attached to the vehicle body metal panels to reduce the radiation of the noise into the vehicle cabin. This study focuses on investigating the effects of porous materials on the noise level due to the structure-borne noise excitation. Because of the complexity of the analysis of noise in a full vehicle cabin, a box cavi...
Article
The self-locking gear has great potential application in controlling the position stability of gearbox, which is a critical requirement in some precision machineries and instruments. This study provides important knowledge about the dynamic performance of self-locking gear pairs. An analytical model of variation ratio of contact length (VRCL) was e...
Article
Full-text available
Measurement over pins is an effective way to gauge and control the quality for the manufacture of gears. However, the conventional calculation process for the dimension of over pins is not convenient and accurate enough to meet the requirement of current engineering design. In this paper, with the help of MATLAB, different algorithms are compared a...
Conference Paper
Characterizing the acoustic properties of sound-absorbing materials is costly and time consuming. The acoustic material database helps the automotive designers design their interior trims in accordance with target level for interior noise. In this paper, a two-microphone impedance tube was used to measure the normal sound absorption coefficient. Th...
Conference Paper
The development and application of the vehicle advanced CAE (computer aided engineering) allowed the vehicle designers to considerably reduce the weight and improve the structural performance of the body. However, the current advanced CAE model can only be available in the late design phase of the vehicle when only minor changes of the structure is...
Conference Paper
Full-text available
A variation in the camber of an automotive wheel is desired to compensate a side-slip force change owing to normal load transfer when the car is cornering. The camber of a steered wheel can be varied by adjusting caster or lean angle which are the representations of steering axis orientation. Thus, a smart camber can be created by a variable caster...
Article
Full-text available
In this paper, an adaptive critic-based neurofuzzy controller is presented for a 2 DOF active vehicle suspension system with a servo hydraulic actuator. Fuzzy critic-based learning is a reinforcement learning method based on dynamic programming. The only information available for the critic agent is the system feedback, which is interpreted as the...
Article
Vehicle crash-can transfers the kinetic energy into strain energy stored in the structure via a sequential deformation wall crushing process. The performance of the crash can FEA model and its ability of predicting mechanical behaviours in a crash event is assessed and verified via the FEA analysis and corresponding experiment data. Compression tes...
Chapter
It was suggested [1] that having natural frequency of the front approximately 80 % of that of the rear suspension in a vehicle will result in a flat ride for the passengers. Flat Ride in this case means that the pitch motion of the vehicle, generated by riding over a bump for instance will fade in to the bounce motion of the vehicle much faster. Bo...