Seat Characteristics Research Articles

Static Factors in Sitting Comfort: Seat Foam Properties, Temperature, and Contact Pressure

The seat characteristics have high relevance in overall comfort on any transportation means. In particular, the foam’s mechanical properties, interface pressure, and contact temperature play an important role in low- or no-vibration situations regarding static comfort. The present work presents the complete protocol for a static evaluation of different foams and seat covers to assess railway seats. Based on the evaluation of the foam’s mechanical properties and interface pressure profiles, it was concluded that higher-density foam (80 kg/m3) is the most favorable. Regarding the foam cover, a thermographic assessment demonstrated that the fabric cover that induces lower temperatures at passenger interface contact promotes higher comfort levels. It should be highlighted that experiments were conducted on real train seat cushions and environments using a thermographic camera and pressure map sensor.

Transmission of vertical vibration through a seat cushion at the seat pan: Effect of foam physical properties during different excitation magnitudes

The vibration characteristics of car seats directly influence the ride comfort. Polyurethane foam is the key part of a seat, and its physical parameters have an important impact on the seat. In this study, the influence of the foam thickness and foam hardness on the vibration characteristics of seat cushion with different excitation magnitudes was investigated by using transmissibility and seat effective amplitude transmissibility (SEAT) value. First, vibration tests were carried out at a vertical vibration simulator with width-limited white noise vibration frequencies from 0.5 to 20 Hz with root-mean-square (r.m.s.) values of 0.4, 0.8, and 1.2 m/s2, the acceleration at the platform and the body-foam interfaces were measured to calculate the transmissibility, and the influence of the foam physical properties on the transmissibility was analyzed. Then, the SEAT value was introduced to assess the vibration isolation efficiency of the foam cushion, and the influence of the foam physical properties of the foam cushion on the vibration isolation efficiency was analyzed. With increasing thickness of the foam and decreasing hardness of the foam at the seat pan, the peak transmissibility increased and the resonance frequency decreased. The SEAT values show that increasing the foam thickness is beneficial to the improvement of the vibration isolation efficiency of the seat, but there is a diminishing return; the combination of physical parameters of low hardness and high thickness could make the vibration isolation performance of the seat better. In addition, the nonlinearity of human-seat system during different vibration magnitude was found.

A Comparative Study of Integrated Vehicle–Seat–Human Models for the Evaluation of Ride Comfort

In the literature the value of the driver’s head acceleration has been widely used as an objective function for the modification of the suspension and/or the seat characteristics in order to optimize the ride comfort of a vehicle. For these optimization procedures various lumped parameter Vehicle–Seat–Human models are proposed. In the present paper a Quarter Car model is integrated with three Seat–Human models with different levels of detail. The level of detail corresponds to the number of degrees of freedom used to describe the Seat–Human system. Firstly, the performance of the Quarter Car model, used as a basis, is analyzed in six excitations with different characteristics. Then, the performance of the three lumped parameter Vehicle–Seat–Human models are monitored in the same excitations. The results indicated that in the case of single disturbance excitations the Quarter Car model provided 50–75% higher values of acceleration compared with the eight degrees of freedom model. As far as the periodic excitation is concerned, the Vehicle–Seat–Human models provided values of acceleration up to eight times those of the Quarter Car model. On the other hand, in stochastic excitations the Vehicle–Seat–Human model with three degrees of freedom produced the closest results to the Quarter Car model followed by the eight degrees of freedom model. Finally, with respect to the computational efficiency it was found that an increase in the degrees of freedom of the Vehicle–Seat–Human model by one caused an increase in the CPU time from 2.1 to 2.6%, while increasing the number of the degrees of freedom by five increased the CPU time from 7.4 to 11.5% depending on the excitation.

Validating Measurement Structure of Checklist for Evaluating Ergonomics Risks in Heavy Mobile Machinery Cabs

Heavy mobile machinery cabs and their equipment are still not well adjusted to operators, so it is not surprising that we are still witnessing huge consequences of accidents at sites where they operate. The checklist with 39 questions, based on the previous research, is formed, and its’ measurement structure has been tested on the sample of 102 transport, construction, and mining machines, including cranes, excavators, bucket wheel excavators, bulldozers, loaders, graders, backhoe loaders, trenchers, dump trucks, and scrapers by correlation analysis, Cronbach’s alpha, Spearman-Brown and Kendall’s W coefficient, exploratory factor analysis, and confirmatory factor analysis. The results validate the measurement structure of a checklist with only 17 items and five constructs. The results show that special attention should be put to the design of armrests and working conditions/exhaust gases, which are negatively correlated to cab interior space and task visibility. All other correlations between seat characteristics, the characteristics of armrests, whole-body vibration influences, reaching commands, the characteristics of cab interior space and environments, and interpersonal relationships are positive, which means that improvements to one area lead to improvements in another. Accordingly, the proposed model should be used for the fast, efficient, and cost-effective evaluation of ergonomics risks and as a guideline for further cab design improvements.

Perceived discomfort and neuromuscular fatigue during long-duration real driving with different car seats.

Identification of the seat features that could improve driving experience is a main issue for automotive companies. Long duration real driving sessions were performed to assess the effect of three seats (soft-S1, firm-S2 and suspended-S3) on perceived discomfort and neuromuscular fatigue (NMF). For each seat, the muscular activity of bilateral Trapezius Descendens (TD), Erector Spinae (ES) and Multifidus (MF) muscles of twenty-one participants was recorded during real driving sessions of 3-hours each lasting approximately 3 hours and following the same itinerary. During each driving session, participants were also regularly asked to self-evaluate their level of whole-body and local discomfort. In addition, an endurance static test (EST) was performed before (ESTpre) and after (ESTpost) each driving session to assess the seat effect on physical capacity. Whole-body discomfort increased with driving time for all seats, but this increase became significant latter for S3. The highest scores of local discomfort occurred for neck and lower back. Contrary to S1 and S2, the duration of ESTpost was not significantly lower compared to ESTpre with the S3. Interestingly, muscular activity of S1 remained stable throughout the driving task which could be attributed to sustained muscular contraction, while muscular recruitment adjustments occurred for S2 and S3 from 1H00 of driving. This muscular compensation concerns mostly the right side for S2 and S3 but with different profiles. On the left side, the muscular adjustments concern only the MF with S2 and the ES with S3. Overall, our results demonstrated that S3 could be considered as the most suitable seat to delay discomfort and NMF appearance.

Influence of car seat firmness on seat pressure profiles and perceived discomfort during prolonged simulated driving

During a driving task, the seat-driver interface is particularly influenced by the external environment and seat features. This study compares the effect of two different seats (S1 – soft & S2 – firm) and the effect of visual simulation of different road types (city, highway, mountain, country), on pressure distribution and perceived discomfort during prolonged driving. Twenty participants drove two 3-h sessions (one per seat) on a static simulator. Contact Pressure (CP), Contact Surface (CS), and Seat Pressure Distribution Percentage (SPD%) were analyzed throughout, using two pressure mats positioned on seat cushion and backrest. Whole-body and local discomfort for each body part were rated every 20 min. The softer seat, S1, induced a greater contact surface on cushion and backrest and a lower SPD%, reflecting better pressure distribution. Pressure profiles were asymmetrical for both S1 and S2, with higher CP under left buttock (LBu) and right lower back (RLb) and greater CS under thighs and RLb. Pressure distribution was less homogeneous on mountain and city roads than on monotonous roads (highway and country). Despite the pressure differences between the seats, however, both led to similar increases in perceived whole-body discomfort throughout the driving session. Moreover, the highest discomfort scores were in the neck and the lower back areas, whatever the seat. These findings on pressure variables may have implications for the design of backrests and cushions to ensure more homogeneous pressure distribution, even though this is not shown to minimize perceived driver discomfort.

Um não-lugar: O simbolismo presente na Rodoviária de Vitória/ES

This paper aimed to analyze whether the bus station in the city of Vitória / ES has characteristics of non-places described by Augé (2012). Several authors treat the idea of place as identity, relational and historical, and the non-place is the opposition to that, in this way, Augé (2012) highlighted some places that generally do not have these characteristics: airports, shopping centers and highways. Thus, the work explored this thought by conducting a study with observations and interviews with people who circulated through the space of the bus terminal. Despite presenting many characteristics of non-seats, it cannot be put as a rule for all passengers, as there are some that break and lead the bus station to have strong seat characteristics.

Attenuation of Mechanical Vibration During Transmission to Human Body Through Mining Vehicle Seats

Operators of mining vehicles are exposed to high levels of whole-body vibration (WBV) and are therefore at risk of developing vibration-related health disorders. For implementing an effective control strategy, it is imperative to locate the source(s) of vibration, and the specific changes that might occur to the vibration signals during its transmission through the seats to the recipient human body. With this objective, Seat Effective Amplitude Transmissibility (SEAT) values of seat modules used in dumpers (n = 10) and other heavy earth-moving machines (n = 11) were evaluated in an iron ore mine. Vibration was measured simultaneously on the seat and on the cabin floor beneath the seat using tri-axial and uni-axial accelerometers. The study aims at determining the quality of seat modules of the transport and non-transport vehicles from the perspective of their natural resonance frequencies and capability of any such seat in reducing harmful vibration. The highest acceleration values were observed in the z-axis for all the dumpers. SEATrms values ranged from 78 to 133% and SEATvdv values ranged from 72 to 130% for the dumpers. For other HEMMs, SEATrms values ranged from 55 to 125% and SEATvdv values ranged from 56 to 123%. Mechanical vibration contains multiple frequency components. To understand the changes taking place to the different signals at these frequencies, 1/3 octave band analysis was carried out for the signals recorded both on the seat and the floor. There was significant attenuation (38 to 57%) at 4 Hz for three Dumper seats, whereas they resonated in the range of 1.6–2.5 Hz. The transmissibility(%) in the resonating frequencies ranged from 108 to 156%. Resonance frequencies for the remaining seven dumpers ranged from 3 to 8 Hz. The spine has been reported to resonate at 4 Hz, whereas resonance at 1.6 Hz has little significance to human beings in regard to WBV of a seated person. Hence, the characteristic resonant frequency of 4 Hz of seats as observed in the present study has the potential of causing adverse impacts on spinal health. Evaluation of SEAT factors and resonance characteristics of seats are therefore recommended to be examined while selecting a mining vehicle for regular deployment in mines.

Seat pitch and comfort of a staggered seat configuration.

BACKGROUND:Staggered seats are a solution for the Flying-V aircraft, where the cabin’s longitudinal axis has a 26 degrees angle with respect to the direction of flight, to compensate for an otherwise oblique sitting position. However, little is known on acceptable pitches in this staggered configuration.OBJECTIVE:The goal of this research is to evaluate the comfort of different pitches for seats that are staggered relative to the cabin’s longitudinal axis.METHODS:Two rows of staggered seats are positioned at three different pitches (27, 29 and 31 inches). 53 participants were seated in each setup. For each, a questionnaire was completed including questions on comfort and discomfort, top view photos were taken to analyse postures and physical dimensions were recorded to define passengers’ space.RESULTS:Comfort as well as discomfort were significantly different for the three setups. The comfort at 27 inches was seen as unacceptably low. The 29 and 31-inch configurations showed to result in acceptable levels of comfort, comparable to higher-end seating layouts. There were very little complaints about space in lateral direction (elbow and seat width), showing the advantage of having your won armrest and shoulder space in the staggered configuration. Interesting was that at larger pitches more complaints were found for the seat characteristics, probably in the shorter pitch the other discomfort was overruling this.CONCLUSION:The 26-degree staggered configuration offers improvements in shoulder- and elbow-space. The results for the 29- and 31-inch are expected to allow enough design freedom for further exploration of such a configuration for the Flying-V cabin interior.

Modeling of a Seated Human Considering the Characteristics of Actual Vehicle Seats

Modeling of a Seated Human Considering the Characteristics of Actual Vehicle Seats

The Design and Analysis of a Child Seat for a Motorcycle

<p>This paper discusses the methodology of design and analysis of a child seat for motorcycles. After realizing the dangers of an unrestrained child in motorcycles, this seat offers a solution to the problem. The seat features sliding beams that allow the user to access the under-seat compartment of the motorcycle and the fuel tank, without requiring any disassembly of the child seat. The dimensions are measured and considered when designing in a graphical application. Once the assembly drawing is completed, the seat is analyzed to identify critical parts of the seat to ensure failure does not occur. It is concluded that our design can withstand static loading but is predicted to fail due to fatigue after 81× 10<sup>3</sup> cycles under the assumption of accelerating from 0 to 50 km/h in 5 seconds. However, since that is not deemed to be fully optimized due to having a finite life, the material and dimensions are changed so that an infinite life can be predicted.</p>

Тушение тлеющего горения опилок

Проанализированы теоретические и известные экспериментальные исследования по тлеющему горению опилок. Разработана методика определения характеристик очагов тлеющего горения. Экспериментально обоснован модельный очаг тлеющего горения. Показано изменение скорости тлеющего горения, массы опилок в зависимости от их дисперсности. Разработана лабораторная методика определения эффективности тушения различными огнетушащими веществами тлеющего горения опилок. Получены экспериментальные результаты по тушению опилок газовыми огнетушащими веществами (ГОТВ), тонкораспыленной водой, а также огнетушащим порошком. The analysis of existing theoretical and experimental studies on smoldering combustion of sawdust is carried out. There are considered the types of smoldering combustion. Practically, there is observed the implementation of three types of smoldering combustion. The first type is the process of oil-carbon sludge smoldering in the final phase of wood burning. The second type is smoldering combustion in dispersed, layered or fibrous carbon-containing materials. The third type of smoldering combustion is typical for carbonaceous materials that do not contain volatile components such as activated carbon. The method for determining the characteristics of seats of smoldering combustion is developed. Wood sawdust of coniferous species of different fractions was used for research. Experimental seats were cylindrical containers with a wall thickness of 1 mm: d = 66 mm, h = 100 mm; d = 72 mm, h = 80 mm; d = 54 mm, h = 100 mm; d = 65 mm, h = 115; d = 100 mm, h = 40 mm; d = 85 mm, h = 85 mm; d = 100 mm, h = 125 mm (d - diameter, h - height of the seat). Smoldering combustion model seat is experimentally proved. Based on the tests performed, a model seat with the height of 85 mm and the diameter of 85 mm was selected for further research (the criterion for seat selecting was the optimal degree of sawdust burnout), in which thermocouples were placed, according to Fig.1. There were used sawdust fractions of less than 0,1 mm, 0,1-0,2 mm, 0,2-0,4 mm and 0,4-1 mm. Sawdust moisture content w = 5 %. Tests were conducted to determine the rate of sawdust smoldering combustion and the maximum temperature of smoldering combustion. There is shown the change both of smoldering combustion rate and the sawdust mass depending on its dispersion. A laboratory method for determining the extinguishing effectiveness of sawdust smoldering combustion with various fire extinguishing agents was developed. The seat was placed into the conventionally sealed chamber of 1 m x 1 m x 1 m at the distance of 0,5 m from the walls. The chamber has lines for supplying bulk fire extinguishing agents, as well as devices for supplying fire extinguishing powders. There are obtained experimental results for extinguishing sawdust with gas fire extinguishing agents, dispersed water as well as with fire extinguishing powder

A comparative study of transmissibility factors of traditional and pneumatic dumper seats using one-third octave band analysis

Severity of exposure to whole-body vibration of vehicle drivers depends on multiple factors including type of vehicle suspension or quality of seats. The study presents analysis of seat vibrations of two different types of dumpers in opencast mines. Since health guidance provided in ISO 2631-1997 are only indicative, seat effective amplitude transmissibility factors along with one-third octave-band analysis of vibration signals have been considered as more effective information for control measures. Vibration characteristics of conventional seats ( n = 3) with rigid frame and those with pneumatic suspensions ( n = 3) have been compared during their use in mines. A(8) values ranged from 0.66 to 1.41 m/s2. All the six operators had shown moderate to higher health risk but this may vary since both intensity and durations of exposure frequently change during the operators’ employment. Vibration signals from a mono-axial accelerometer (z′) placed on the cabin floor was captured in addition to three channel vibration data (x, y and z) of a seat pad accelerometer placed on the vehicle seat. Transmissibility analysis of vibration signals from cabin floor to seat surface showed that the three pneumatic seats resonated in the range of 1.6–2.5 Hz in the z axis. There was significant attenuation of vibration energy ranging from 37% to 63% at 4 Hz which is important in the context of spinal injuries. The seat effective amplitude transmissibility values (%) in the resonating frequencies ranged from 119% to 173%. Interestingly, the conventional seats resonated at 4–5 Hz and the corresponding seat effective amplitude transmissibility (%) values were varying from 128% to 163%. This resonance at 4 Hz is in sharp contrast with the behaviour of pneumatic seats. It is recommended that vibration transmissibility should be considered as a major design parameter for mining vehicle seats.

Neuromuscular fatigue profiles depends on seat feature during long duration driving on a static simulator

Prolonged driving could induce neuromuscular fatigue and discomfort since drivers have little opportunity to adjust their position. However, better car seat design could play a major role in limiting these effects. This study compared the effect of two different seats (S - soft and F - firm) on neuromuscular fatigue and driver's perceived discomfort during prolonged driving, also assessing the effect of different road types on neuromuscular activity. Twenty participants performed two 3-h driving sessions, one for each seat, on a static simulator. Every 20 min, participants self-evaluated their level of whole-body and individual body-area discomfort. Surface electromyography (sEMG) was recorded for eight muscles including Trapezius descendens (TD), Erector spinae longissimus (ESL), Multifidus (MF), Vastus lateralis (VL) and Tibialis anterior (TA) throughout the driving sessions. Moreover, an endurance static test (EST) was performed prior to and after each driving session. Whole-body discomfort increased with time with both seats, but no difference in discomfort scores was observed between seats throughout the driving sessions. The highest discomfort scores were for neck and lower back areas with both seats. Neuromuscular fatigue was revealed by a shorter endurance time in post-driving EST for both seats. EMG recordings showed different neuromuscular fatigue profiles for the two seats, with earlier onset of fatigue for S. Despite the lack of difference in perceived discomfort level, the two seats have different impacts: the softness of S induces greater activity of the lower back muscles, while F offers greater support for the lower back.

An efficient airline seat reallocation algorithm considering customer dissatisfaction

Nowadays, many airlines tend to provide an advance seat selection service to maximize customer satisfaction to secure market shares in the competitive air transport market. However, the preassigned seat configuration of certain flight legs can be changed often due to aircraft changes for certain reasons, such as maintenance and reservation rates. Then certain customer's seat features, such as row location, position of aisle/window, relative location, and position with the same group member can be different before/after the change, and it can lead to huge customer dissatisfaction. Therefore, an efficient airline seat reallocation algorithm to minimize customer dissatisfaction is introduced in this study, which is based on mathematical model-based optimization with several types of objective functions that reflect customer dissatisfaction levels. A numerical example is performed to validate the developed airline seat reallocation algorithm, and an additional analysis is also executed to derive important insight.

A model-based approach for the analysis of aircraft seating comfort.

Aircraft seating comfort has a significant impact on passenger on-board experience. Its assessment requires the adoption of well-designed strategies for data collection as well as appropriate data analysis methods in order to obtain accurate and reliable results. This paper focuses on the assessment of aircraft seating comfort based on subjective comfort responses collected during laboratory experiments and taking into account seat features and passenger characteristics. The subjective comfort evaluations have been analyzed using a model-based approach to investigate the relationship between overall seating comfort and specific seat/user characteristics. The results show that the overall seating comfort perception is significantly influenced by the thickness of the seat pan, the backrest position (upright or reclined), the age of the passenger and the passenger perception of being comfortably supported at the lumbar region. The adopted model-based approach allows the analysis of subjective seating comfort data taking into account their ordinal nature as well as the dependency between evaluations provided by the same subject.

A multifactorial approach to specify comfortable rail seats.

A robust rail seat comfort assessment can inform the GB rail industry when procuring new seats and identify areas for comfort improvement in the refurbishment of existing seats, improving the customer experience. To take a multifactorial approach to measuring comfort and to create a robust seat comfort assessment method for the GB rail industry. Seat comfort assessment scores were developed by identifying seat dimensions (e.g. Seat height, seat width, seat depth), seat pad thickness and hardness requirements, seat accessories and seat attractiveness components. Scores for each seat feature were verified by conducting a fitting trial and asking 7 participants to rank dimensions through a range of adjustment. The combined scoring of features was verified by asking 14 participants to rank seats in three configurations (<minimum comfort; minimum comfort;>minimum comfort). The seat comfort dimensions scores were then validated by ranking seven existing rail seats using the assessment method and comparing the ranks with subjective comfort ranks of 12 participants. The validation testing resulted in a moderate positive correlation, indicating an alignment between the seat comfort assessment method and subjective comfort scores. A multifactorial seat comfort assessment has been shown to be a good indicator of passenger seat comfort.

RELATIONSHIP BETWEEN SATISFACTION WITH COMPLETE DENTURES AND BASAL SEAT CHARACTERISTICS

Aim: To investigate the relationship between patients self perceived satisfaction and basal seat characteristics in edentulous patients attending a teaching hospital in Lagos.Materials and Methods: Consecutive edentulous patient seen for 6 months in Lagos University Teaching Hospital, Lagos were recruited for this longitudinal study. The data collected were basal seat characteristics and self perceived satisfaction.Results: A total of 30 patients were seen but only 24 complied with the study protocol. The use of objective assessment in classifying maxillary residual ridge showed that there was a significant association (P=0.045) between the ridge and self perceived satisfaction. There was no significant association between self perceived satisfaction and shape of mandibular ridge, palatal vault and vestibular depth.Conclusion: There was a significant association between shape of maxillary residual ridge and self perceived satisfaction. Objective preclinical assessment of residual ridge may help to project satisfaction and determine treatment option.

Analysis of body pressure distribution on car seats by using deep learning

This study aimed to extract information from body pressure distribution, including comfort, participant body size, and seat characteristics by using supervised deep learning, and body pressure characteristics corresponding to sensory evaluation by using unsupervised deep learning. Body pressure data of 18 participants and 19 kinds of car seats were used for the analysis. Sensory evaluation of 9 items concerning cushion characteristics and seat comfort was conducted. From the analysis, we determined that body size and car seats could be classified with high precision by using body pressure distribution data. For the sensory evaluation items, the correct answer rate was high. By examining the importance of the cells of the mat, the features of the body pressure mat at the seat cushion and backrest, body size, car seat, and parts related to sensory evaluation could be determined in detail. The study findings can be applied in the development of car seats.

Study on the comfort of high-speed train drivers in a windy environment

Conducting the study on the comfort of high-speed train drivers in a windy environment, this paper based on the logical sequence of “train aerodynamic characteristics - vehicle dynamic response - human biomechanical properties - human body comfort evaluation”. Taking the domestic CRH3 high-speed train as the research object. Firstly, the aerodynamic loads acting on the car bodies of the train under different wind speeds and different vehicle speeds were calculated. Then considering the effect of the wheel-rail adhesion and the irregularity of the track line, establish a vibration transfer model of ‘rail - wheelset - bogie - carriage - seat’, the aerodynamic loads are loaded onto the train to calculate vehicle dynamics and train vibration response under different operating conditions, the vibration characteristics of carriages and seats are obtained. Subsequently, the seat-human vibration transfer model were established and the seat vibration response was introduced into the human dynamics model to calculate the vibration response of different body parts of the driver under different operating conditions. And on the basis which are mentioned above, we summarized the influence rule of wind speed and train speed on human vibration response, From the human body's own point of view, the main factors affecting comfort and the mechanism of action were analyzed. Finally, the comfort standard was integrated to evaluate the comfort of the driver.