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Mode shape of 54 kg human subject at natural frequency (a) 3.6 Hz, (b) 4 Hz, (c) 14.8 Hz, (d) 17.9 Hz, (e) 20.6 Hz and (f) 28.3 Hz
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Biodynamic response of a human body can be studied using different techniques i.e. Lumped Parameter Modeling (LPM), Finite Element Modeling (FEM), Multi-Body Dynamics (MBD) and experimental investigations. In this study, modal analysis has been performed for two different Indian male subjects (in standing posture) using FEM under free un-damped vib...
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... results obtained after performing modal analysis i.e. natural frequencies and mode shapes of Indian male human subject of 54 kg in standing posture obtained under un-damped free vibration conditions are shown in Figure 1 and are discussed as follows:At natural frequency of 3.6 Hz as shown in (Figure 1a), lower segments of human body remain fixed and upper part segments (lower torso, upper torso, upper arms, lower arms, head and neck) of human body move along fore-and-aft direction. ...
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... results obtained after performing modal analysis i.e. natural frequencies and mode shapes of Indian male human subject of 54 kg in standing posture obtained under un-damped free vibration conditions are shown in Figure 1 and are discussed as follows:At natural frequency of 3.6 Hz as shown in (Figure 1a), lower segments of human body remain fixed and upper part segments (lower torso, upper torso, upper arms, lower arms, head and neck) of human body move along fore-and-aft direction. ...
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... this mode shape, a human body acts like a cantilever beam. At natural frequency of 7.4 Hz as shown in (Figure 1b), human body moves along a lateral direction and all body segments are deformed except feet as they are fixed to a floor. This mode corresponds to a second mode shape of cantilever beam. ...
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... mode corresponds to a second mode shape of cantilever beam. As shown in (Figure 1c (Figure 1f), all body segments (except feet) moves in fore-and-aft direction about a node between lower torso and central torso. Maximum deformation is seen at lower arms and hands. ...
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... mode corresponds to a second mode shape of cantilever beam. As shown in (Figure 1c (Figure 1f), all body segments (except feet) moves in fore-and-aft direction about a node between lower torso and central torso. Maximum deformation is seen at lower arms and hands. ...
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... analysis of 54 kg and 76 kg Indian male subjects has been performed in present study using FEM to find out the natural frequencies and behavior of human subjects at different natural frequencies. It has been observed that at first fundamental mode, natural frequency of 54 kg and 76 kg human subjects is 3.6 Hz (Figure 1a) and 3.4 Hz (Figure 2a), respectively. At this mode, it has been observed that whole human body (except feet) moves along fore-and-aft direction with maximum deformation at head and minimum deformation at feet and lower legs. ...
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... might be due to the reason that a human body acts like a cantilever beam (in this study) in which feet are fixed. At second mode as shown in (Figure 1b) and (Figure 2b), motion in human subjects is in lateral direction motion with no deformation at lower legs and feet. This justifies the basic concept that at second mode cantilever beam moves along lateral direction. ...
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... justifies the basic concept that at second mode cantilever beam moves along lateral direction. At third mode, natural frequency of 54 kg mass is 14.8 Hz (Figure 1c) and 76 kg mass is 15.9 Hz (Figure 2c) and the difference in results may be due to mass variation. It has been observed that at this mode, there obtained one pivot point between lower torso and upper logs about which upper body segments (head, neck, upper torso, central torso, upper arms and lower arms) and upper legs moves along fore-and-aft direction. ...
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... point between central torso and lower torso acts as a pivot point for this to-and-fro motion along lateral direction. Natural frequency at this mode is 17.9 Hz and 16.0 Hz as shown in (Figure 1d) and (Figure 2d) for 54 kg and 76 kg Indian male, respectively. At fifth mode, natural frequency for 54 kg human male subject is 20.6 Hz ( Figure 1e) and for 76 kg male is 16.3 Hz (Figure 2e). ...
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... frequency at this mode is 17.9 Hz and 16.0 Hz as shown in (Figure 1d) and (Figure 2d) for 54 kg and 76 kg Indian male, respectively. At fifth mode, natural frequency for 54 kg human male subject is 20.6 Hz ( Figure 1e) and for 76 kg male is 16.3 Hz (Figure 2e). Also, at this mode maximum deformation has been observed at lower arms and hands in both the cases. ...
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... this mode, upper body segments rotate along vertical direction about a connecting point between central torso and lower torso. At sixth mode (Figure 1f and 2f) natural frequency of 54 kg mass is 28.3 Hz and 76 kg mass is 23.9 Hz. At this mode, whole body (except feet) moves in fore-and-aft direction about a connecting point between lower torso and central torso. ...
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Human subject suffers from many problems when it comes into contact with conditions of vibrations while travelling, working etc. in sitting posture. This result into a headache, body ache, increase in heart rate etc., therefore it becomes necessary to study the Whole body vibrations effect on human subject. Taking this into investigation, a current...
Citations
... They also validated finite element results with real-time testing and they found that there is good compliance between experimental and numerical results. Many researchers used 50th percentile anthropometric data for a seated 54 kg Indian male to model a semi-supine posture [18][19][20][21][22] and performed modal and harmonic response analysis to find the natural frequency, mode shape, and effect of vibration on the occupants. They observed that maximum deformation and stresses occurred when the model vibrated in the lateral direction. ...
... 4.3. The damping factor of 0.4 was taken from the previous research work [20]. The results of the modal analysis and the frequency range of 9.0611 Hz to 91.686 Hz are given in Table 12. ...
Vibrations are generated in the vehicles due to the uneven texture of the road and transferred to the occupants via tires, chassis, seats, bodies, and different parts of the vehicles. This kind of vibration is also known as Whole-Body Vibration (WBV) because the whole body of an occupant inside the vehicle experiences a force due to vibration. The comfort, performance, and long-term health of the occupant are impacted by the WBV transmission. This research study deals with the measurement and assessment of discomfort due to the WBV experienced by a passenger under seating posture inside the OMNI-E vehicle, with and without the use of polyurethane (PU) foam padding. Vibration at the seat, lower back, and floor of the car were recorded at four different speeds, i.e., 30, 40, 50 and 60 km/hr. The vehicle’s seat effective amplitude transmissibility (SEAT) was assessed for both scenarios with and without padding. The reduction in the SEAT and acceleration values were computed to check the effectiveness and accuracy of the padding used in the investigation. Modal and harmonic (frequency response) analysis is performed on a 3D ellipsoidal human body model based on anthropometric data of the 50th percentile Indian male of 54 kg mass under damped vibration condition to examine the influence of vibration experienced by the passenger in the seating posture. The ellipsoidal human body model was modeled and assembled in SOLIDWORKS®2021 and the modal analysis on ellipsoidal human body model was performed to determine its natural frequencies since the human body is sensitive to low-frequency vibration. By utilizing the experimental acceleration values with and without padding, frequency response analysis was carried out throughout the frequency range of 0–9 Hz, and the maximal equivalent stresses corresponding to 9 Hz frequency were estimated by ANSYS®2022 Workbench. The obtained results showed that the amplitude of stresses was minimized with padding as compared to without padding. Thus, vibration has a low adverse impact on human muscles and occupants are less venerable to suffer from back injuries, muscle pain, disorders, etc. It leads to improvement in the overall comfort of the occupants.
... So during design the solid model some assumptions has been considered from existing literature that the density and different biomechanical properties of the different segments of the human body is taken to be same as the average density of whole body [14]. The biomechanical properties isE (Modulus of elasticity) = 13 MN/m 2 , Poisson ratio = 0.3 and human subject density = 1.062˟10 3 kg/m3 [15]has been used for the considered solid model. The different segments of solid model has been considered from taking reference from existing literature [2]. ...
Human body exposed to vibration for make their work easy and comfortable that causes various types of various types of health problems due to the vibration effect on the human subject. Seat to head transmissibility as harmonic analysis has been performed on the 54 kg ellipsoidal shape human subject in the vertical sitting posture at excitation acceleration 1 m/s 2 between frequency range 0-20 Hz with different damping conditions 0.2, 0.3 and 0.5. The solid model of the human subject has been designed by considering 50 th percentile anthropometric data of Indian male subject. By performing harmonic response on the human subject it has been found that, at frequency 6 Hz the maximum effect of vibration has been occurred with the entire damping ratio. And also it has been observed that due to increasing of the damping ratio the effect of vibration has been decreases. The effect of the vibration has been occurred at various body parts like back, head, lower arm, etc. but the maximum effect has been found at head due to which the human feel sickness like headache, motion sickness, etc. during the traveling on the automotive. So it has been conclude that during the design of the seat in the transportation for the human comfort then the good quality seat cushion has to be used in more quantity.
... For male this model as real human subject, different biomechanical properties has been assigned that 3D CAD model of human subject as response like real human subject. The biomechanical properties has been considered to be Poisson ratio = 0.3, 13 MN/m 2 as the value of Modulus of elasticity and density with value of 1.062˟10 3 kg/m3 [15]. There is non-linear dynamic response of human body due to complex structure that varies while coming in contact with any condition of vibration. ...
Human body experienced uncomfortable when exposed to vibration condition during working, traveling in automobile and other work in standing and sitting posture. During this work, the human subject behavior has been observed using modal analysis while in standing as well as sitting posture. The 3D CAD model has been considered by the ellipsoidal approach that anthropometric data corresponds to 50 th percentile has been considered to model 54 kg male human body belonging to Indian population in sitting posture and 95 th percentile anthropometric data has been taken for modeling 76 kg mass human subject while in posture of standing. The results evaluation has been done in this study and found that a maximum vibration effect transmit from head towards lower arms by increasing in natural frequencies i.e. 3.22 Hz to 20.65 Hz in sitting posture and 4.25 Hz to 29.54 Hz in standing posture. And it will be helpful for construction of component for use of human like in machine parts, automotive sector, escalators, etc. the comparison between standing and sitting posture results observed that the decrease in deformation has been observed while with the rise in natural frequency for both postures.
Human subjects are exposed to vibration while performing different activities in both sitting and standing postures. The amplitude and intensity of vibration vary according to road conditions, environmental conditions, time and other related factors. It becomes necessary to find out the effect of vibration on human subjects in terms of transmissibility, natural frequencies and resonant frequency. In the present study, a 4-layer CAD model of a human subject has been used to perform a harmonic analysis, i.e., applying a sinusoidal input with an acceleration of 1 m/s2 and a frequency range of 0–20 Hz in the vertical direction. The CAD model of the human subject has been developed using 95th percentile anthropometric data and consists of four different anatomy layers, i.e., organs, skin, muscles and bones. The feet-to-head transmissibility has been evaluated for each posture and compared with the available experimental results in the literature. The transmissibility in sitting posture was found to be more in comparison to standing posture.
Background:
In order to alleviate muscle fatigue and improve ride comfort, many published studies aimed to improve the seat environment or optimize seating posture. However, the effect of lumbar support on the lumbar muscle of seated subjects under whole body vibration is still unclear.
Objective:
This study aimed to investigate the effect of lumbar support magnitude of the seat on lumbar muscle fatigue relief under whole body vibration.
Methods:
Twenty healthy volunteers without low back pain participated in the experiment. By measuring surface electromyographic signals of erector spinae muscles under vibration or non-vibration for 30 minutes, the effect of different lumbar support conditions on muscle fatigue was analyzed. The magnitude of lumbar support d is assigned as d1= 0 mm, d2= 20 mm and d3= 40 mm for no support, small support and large support, respectively.
Results:
The results showed that lumbar muscle activation levels vary under different support conditions. For the small support case (d2= 20 mm), the muscle activation level under vibration and no-vibration was the minimum, 42.3% and 77.7% of that under no support (d1= 0 mm). For all support conditions, the muscle activation level under vibration is higher than that under no-vibration.
Conclusions:
The results indicate that the small support yields the minimum muscle contraction (low muscle contraction intensity) under vibration, which is more helpful for relieving lumbar muscle fatigue than no support or large support cases. Therefore, an appropriate lumbar support of seats is necessary for alleviating lumbar muscle fatigue.
