Vibration Study in Human-Car Seat System: Overview and a Novel Simulation Technique

This paper will propose a complete solution with a novel simulation set up to get the final vibration data of seated human body inside an automobile structure without carrying out measurement tests. Furthermore, it will improve the existing technology in assessing the dynamic interaction between the human body and a car seat subjected to different conditions and establish a clear idea about the vibration effects, vibration transmissibility, damping, variable stiffness, natural frequencies, modal analysis, random vibration, harmonic aspects, mode superposition, response spectrum, transient effects etc. The research will provide a novel solution of the entire system rather than focussing only on a very specific portion of the system, thus, trying to close the gap in present technological areas and omitting the time consuming and expensive testing methods in the modern industries. This research will contribute a cutting edge landmark by providing a simulation model to predict final vibration level inside the human body and car seat to avoid the time consuming and expensive testing methods. It will help better understanding the impact and estimation of the vibration level inside the car seat and occupant human body.The non-linear dynamic aspects and efforts will be made to understand, characterize and optimize the level of vibration by establishing a computational simulations model of the car seat and the occupant to match the experimental results.Some technologies have been achieved to judge the dynamic interaction between the human body and a car seat, though such technologies cover only either vibration effects or dynamics or measurement techniques or small portion of the car and human body without considering all the real life factors like pre-stressed bodies, variable stiffness, equivalent stiffness and damping factors based on the behaviour of the human muscles, bones and postures.So, efforts will be made to establish numerical and simulation models for the non-linear bio-dynamics of the seated human body, polyurethane foam cushions, dynamic contacts between the human body and the seat, occupant under the real life car motion, vibration testing of the car seat and finally, to provide a comprehensive solution to judge the vibration levels, which eventually will lead the various industries to avoid the time consuming and expensive testing methods

Vibration in Car Seat- Occupant System: Overview and Proposal of a Novel Simulation Method

In the modern automotive industries, vibration levels inside the human body and the car seat are mainly validated using the on-road vehicle testing or laboratory experiment. This paper aims to propose a novel bio-dynamic simulation technique which will provide the level of vibration in terms of acceleration, displacement or velocity inside the car seated human body and the car seat itself. There are many existing simulation technologies in the market to provide vibration related solution for a specific portion or sub-portion of the human-car seat system, but this proposed novel simulation method will give a complete solution for the entire human body and car seat assembly inside an automotive structure under real life operating condition without conducting any real experiment and testing. Accomplishment of this project will take the existing technology to an advanced level to assess the dynamic interaction between the automotive seat and human mass and help to understand the effect of vibration in a clearer way by judging the three directional stiffness and damping values, mode shapes, random vibration, power spectrum, resonance frequencies and vibration transmission. This research will help to predict the final vibration data at different locations of the human and automotive seat, thus will try to fill up the gap in the latest technologies and omit the necessity of the expensive and robust experimental methods. A cutting-edge technology will be achieved by this unique bio-dynamic simulation technique to understand the effects and estimation of level of vibration inside the car seat and its occupant

Compact System for Measuring Vibration at Different locations of Car Seat and Human Driver in Dynamic Condition

Vibration occurrence during the transportation is one of the key factors to characterize the driver’s and passenger’s comfort level. Piezoelectric accelerometers are most commonly used for measuring the vibration, though not suitable for low frequency ranges. For precise measurement of low level frequency, sensors capable of measuring accelerations to be utilized. Micro-electro-mechanical-system (MEMS) or Integrated Electronics Piezo-Electric (IEPE) are known as most appropriate sensors to be used to measure vibration to the sub-Hertz region. An in-vehicle compact vibration measurement system had been designed using NI 9234 Module and single axis IEPE transducer. Dytran 3055 was connected to data acquisition software in a laptop through USB cable. The signalfrom Digital Read Out (DRO) system were gathered in .SOT format and was processed through the “m+p Analyzer” software tool developed by m+p international. Vertical vibration data in terms of acceleration at various locations of car seat and human driver had been collected from the test run and presented in this paper

Unique Finite Element Modelling of Human Body Inside Accelerating Car to Predict Accelerations and Frequencies at Different Human Segments

The comfort level of the human occupant inside a dynamic vehicle is dependent on the level of vibration generated inside the different segments of the human body. Some technologies have been developed to provide the final level of vibration inside an automotive-seated human, but those technologies considered only a specific portion of human segments. In the present work, a unique and comprehensive finite element simulation model was proposed to predict the final level of vibration at different segments of a seated human driver inside a moving car. The main aim of this unique simulation methodology was to replace the time-consuming and expensive real life vibration testing for a car-seated human body, with a non-robust and correctly postured virtual human model in a finite element environment. The output of this research work focused on the vertical accelerations, vertical displacement, and frequency, and the results obtained from this research work were validated through comparison to real life test data and information provided in other similar research works. The validation study showed that this unique simulation methodology can successfully be implemented to anticipate accelerations and frequencies at different points of a car-seated human body in order to optimize human health, comfort, and safety

Finite Element Modelling of Car Seat with Hyperelastic and Viscoelastic Foam Material Properties to Assess Vertical Vibration in Terms of Acceleration

Primary objective of automobile seats is to offer adequate level of safety and comfort to the seated human occupant, primarily against vibration. Ideally, any sort of automotive seat is constructed by mechanical framework, cushion, backrest and headrest. The frame structures are made of metallic alloys, while the cushion, backrest and headrest are made of polyurethane foam material. During the design phase of automotive seat, the greatest challenge is to assign realistic material properties to foam material; as it is non-linear in nature and exhibit hysteresis at low level stress. In this research paper, a car seat has been modelled in finite element environment by implementing both hyperelastic and viscoelastic material properties to polyurethane foam. The car seat has been excited with the loads due to car acceleration and human object and the effects of vibration in terms of vertical acceleration at different locations have been measured. The aims of this simulation study are to establish a car seat with the foam material properties as accurately as possible and provide a finite element set up of car seat to monitor the vertical acceleration responses in a reasonable way. The RMS acceleration values for headrest, backrest and cushion have been found to be 0.91 mm/sec², 0.54 mm/sec² and 0.47 mm/sec², respectively, which showed that the car seat foam can effectively be modelled through combined hyperelastic and viscoelastic material formulations. The simulation outputs have been validated through real life testing data, which clearly indicates that this computerized simulation technique is capable of anticipating the acceleration responses at different car seat segments in a justified way

Modelling the Car Seated Human Body using Composite Ellipsoidal Bodies and Evaluation of Size and Shape Specific Stiffness Data for Various Human Segments

Automobile is one of the primary modes of worldwide transport system, which must offer highest level of health, safety and comfort levels for the occupants inside. Health, safety and comfort of any moving vehicle and its human occupants are mainly characterized by the level of the vibration generated inside the human body. With the development of modern computer based technologies, over last few decades computerized simulations have been gaining huge importance to anticipate the level of vibration generated inside the automotive seated human body. Many simulation based research works had been conducted in past to predict the effect of vibration inside automotive-human assembly, though one of the key parameters to define the simulation set up, namely stiffness values of different human segments; had been collected from past relevant research studies or available testing data resources, which overlooked the real shapes and sizes of the human portions, hence, lacking the practical feasibility. In this research paper, a simplified car seated human made of ellipsoidal segments has been proposed. The segmental dimensions and masses have been extracted from anthropometric database and later, the formulations for composite fibre-matrix configuration have been implemented. A systematic approach has been outlined to evaluate the three-dimensional stiffness values for all the human portions. The obtained stiffness values have been validated by comparing to the data obtained from similar kind of investigations and test results

Food intake, growth, food conversion, and body composition of catfish exposed to different salinities

The effects of different salinities (0, 2, 4, 6 and 10‰) on food intake, growth, food conversion, and body composition of the freshwater catfish Mystus vittatus (Bloch) were studied. Under a restricted feeding schedule daily intake of food was found to be salinity dependent. Fish reared in 10‰ consumed more Tubifex tubifex, converted less efficiently and displayed poor growth as compared to individuals reared in fresh water. Fish flesh production decreased from 483 g (fresh water) to 177 g (10‰ salinity) as the salinity was increased. Water content of the fish was found to decrease with increase in salinity, while maximum ash (25.56%) and fat (42.25%) were exhibited by fish reared in 10‰ salinity. © 1979

Influence of Interstitials on the mechanical properties of group IV b metals

THE spectacular progress in nuclear technology and space science researches has brought in a vigorous inte-rest in the properties of IV b metals, titanium, zir- conium and hafnium and their alloys. In most of the engineering applications, the properties of pure metals themselves would be clearly insufficient:alloying with other elements would be called for, be it for increase in strength and fracture toughness, or for better super conducting properties. Group IV b metals are somewhat unique in their alloying behaviour as they form solid solutions not only with substitutional alloying additions, but also rather extensively with interstitial elements hydrogen, carbon, oxygen and nitrogen. Generally, these elements are not soluble to any remarkable degree in metals and they readily form second phase compounds when present over few parts per million. IV b metals, perhaps helped by their crystal structure and accompanying large interstices, are able to accommodate these elements in their original lattices themselves, thus leading to dras-tic alterations in their mechanical and physical prop-erties. It is the purpose of this review to consider the influence of interstitials on the mechanical properties of group IV b metals. This must be of recurrent interest to those engaged in investigations connected with the metallurgy of Ti, Zr and Hf and their alloys