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Two of the main design objectives for car interiors are comfort and safety. These aspects are both determined by the seating position of the occupant. Seat manufacturers use the SAE Three-Dimensional H-Point Machine™ to measure seating positions to design, audit, and benchmark seats. The seating positions measured with the H-Point Machine form the basis of a seat design, including comfort and safety aspects. Currently, the seat design process is largely based on prototype testing, which makes this process time-consuming and expensive. Consequently, there is a large demand for efficient design tools that enable an optimal combination of seating comfort and safety aspects. Numerical modeling provides an efficient means to optimally combine various seat design characteristics prior to prototype testing, thereby reducing design costs and time-to-market. Therefore, the ability to predict the H-point and the corresponding comfort and safety aspects in the early stages of the seat design process is extremely valuable to car and seat manufacturers. This paper presents a numerical model of the commonly used SAE Three-Dimensional H-Point Machine™. The model was developed using a combination of multibody and finite element (FE) techniques. The applicability of the H-Point Model was verified in two steps. Firstly, tests in which the H-Point Machine was placed on a block of foam were simulated. The measured position of the H-Point Machine was compared to that predicted by the model. After this, the H-Point Model was used together with a full FE seat model to predict the H-point of an actual car seat. The predictions with the H-Point Model were also compared with similar simulations with a FE model of the human pelvis. The FE pelvis model provides a more realistic prediction of the seating posture of a real human, since the deformation of the flesh is incorporated in this model. Based on the simulations, it can be concluded that the H-point can be accurately predicted with the numerical approach presented in this paper. The level of accuracy was found to greatly depend on how accurate the seat foam is modeled (e.g. mesh density, foam characteristics).

Two of the main design objectives for car interiors are comfort and safety. These aspects are both determined by the seating position of the occupant. Seat manufacturers use the SAE Three-Dimensional H-Point Machine™ to measure seating positions to design, audit, and benchmark seats. The seating positions measured with the H-Point Machine form the basis of a seat design, including comfort and safety aspects. Currently, the seat design process is largely based on prototype testing, which makes this process time-consuming and expensive. Consequently, there is a large demand for efficient design tools that enable an optimal combination of seating comfort and safety aspects. Numerical modeling provides an efficient means to optimally combine various seat design characteristics prior to prototype testing, thereby reducing design costs and time-to-market. Therefore, the ability to predict the H-point and the corresponding comfort and safety aspects in the early stages of the seat design process is extremely valuable to car and seat manufacturers. This paper presents a numerical model of the commonly used SAE Three-Dimensional H-Point Machine™. The model was developed using a combination of multibody and finite element (FE) techniques. The applicability of the H-Point Model was verified in two steps. Firstly, tests in which the H-Point Machine was placed on a block of foam were simulated. The measured position of the H-Point Machine was compared to that predicted by the model. After this, the H-Point Model was used together with a full FE seat model to predict the H-point of an actual car seat. The predictions with the H-Point Model were also compared with similar simulations with a FE model of the human pelvis. The FE pelvis model provides a more realistic prediction of the seating posture of a real human, since the deformation of the flesh is incorporated in this model. Based on the simulations, it can be concluded that the H-point can be accurately predicted with the numerical approach presented in this paper. The level of accuracy was found to greatly depend on how accurate the seat foam is modeled (e.g. mesh density, foam characteristics).

This paper presents ail evaluation of thermal comfort in ail extended road trial study. Automobile seats play an important role in improving the thermal comfort. In the assessment of thermal comfort in autos, in general subjective and objective measurements are used. Testing on the road is very difficult but real traffic conditions affect the comfort level directly, as well as the driver's experience to real conditions. Thus, for such cases real traffic situations should not be neglected in the evaluation of comfort. The aim of this study was to carry out, on an extended road trial study, ail evaluation of thermal comfort using human subjects. In the experiments used, the 100% polyester seat cover had three different cover materials, which were velvet, jacquard and micro fiber. All experiments were carried Out on a sunny day with tell participants over I h. They were carried out at air temperatures of 25 degrees C in a Fiat Marea 2004, which had an automatic climate function. Skin temperature at eight points and skill wettedness at two points on the human body were measured during the trials. Participants were required to complete a questionnaire of 15 questions, every 5 min. It can be concluded that there was negligible difference in participants' reported thermal sensation between the three seats. According to objective measurement results, all seat cover materials have the same degree of thermal comfort. Oil the road the participants feel warmer around their waist than any other area of the body. It was suggested that the effects of real traffic conditions must be accounted for in comfort predictions.

The development of more comfortable seats is an important issue in the automotive industry. However, the development of new car seats is very time consuming and costly since it is typically based on experimental evaluation using prototypes. Computer models of the human-seat interaction could accelerate this process. The objective of this paper is to establish a protocol for the development of seat models using numerically efficient simulation techniques. The methodology is based on multi-body techniques: arbitrary surfaces, providing an accurate surface description, are attached to rigid bodies. The bodies are connected by kinematic joints, representing the seat back recliner and head restraint joint. Properties of the seat foam and frame have been lumped together. Further, experiments have been defined to characterise the mechanical properties required for the seat model for comfort applications. The protocol has been exemplified using a standard car seat. The seat model has been validated based on experiments with rigid loading devices with human-like shapes in terms of force-deflection characteristics. The response of the seat model agrees well with the experimental results. Therefore the presented method can be a useful tool in the seat development process, especially in early stages of the design process.

The development of more comfortable seats is an important issue in the automotive industry. However, the development of new car seats is very time consuming and costly since it is typically based on experimental evaluation using prototypes. Computer models of the human-seat interaction could accelerate this process. The objective of this paper is to establish a protocol for the development of seat models using numerically efficient simulation techniques. The methodology is based on multi-body techniques: arbitrary surfaces, providing an accurate surface description, are attached to rigid bodies. The bodies are connected by kinematic joints, representing the seat back recliner and head restraint joint. Properties of the seat foam and frame have been lumped together. Further, experiments have been defined to characterise the mechanical properties required for the seat model for comfort applications. The protocol has been exemplified using a standard car seat. The seat model has been validated based on experiments with rigid loading devices with human-like shapes in terms of force-deflection characteristics. The response of the seat model agrees well with the experimental results. Therefore the presented method can be a useful tool in the seat development process, especially in early stages of the design process.

This paper presents a detailed numerical model of the human body that can be used to evaluate both safety and comfort aspects of vehicle interiors. The model is based on a combination of rigid body and finite element techniques to provide an optimal combination of computational efficiency and accuracy. All main articulations are implemented and the skin is modelled in detail to provide accurate interactions with the vehicle interior, such as seat, belts, and airbag. The biofidelity of the model has been verified extensively for both crash safety and seating comfort loading, using volunteer and PMHS data. Detailed models of various body parts can be incorporated to study the response of these body parts in more detail. The human models has been used to study and improve vehicle passive safety design for a range of accident scenarios, in particular for those loading scenarios where the current crash dummies are considered insufficiently biofidelic. Ongoing developments include further enhancement of scalability, injury predictive capabilities, and modularity of detailed component models. The human model is aimed to provide a virtual testing tool for integrated safety and ergonomics design. The human model could also be applied in sports and personal protection design.

This paper presents a detailed numerical model of the human body that can be used to evaluate both safety and comfort aspects of vehicle interiors. The model is based on a combination of rigid body and finite element techniques to provide an optimal combination of computational efficiency and accuracy. All main articulations are implemented and the skin is modelled in detail to provide accurate interactions with the vehicle interior, such as seat, belts, and airbag. The biofidelity of the model has been verified extensively for both crash safety and seating comfort loading, using volunteer and PMHS data. Detailed models of various body parts can be incorporated to study the response of these body parts in more detail. The human models has been used to study and improve vehicle passive safety design for a range of accident scenarios, in particular for those loading scenarios where the current crash dummies are considered insufficiently biofidelic. Ongoing developments include further enhancement of scalability, injury predictive capabilities, and modularity of detailed component models. The human model is aimed to provide a virtual testing tool for integrated safety and ergonomics design. The human model could also be applied in sports and personal protection design.

The importance of comfort for the automotive industry is increasing. Car manufacturers use comfort to distinguish their products from their competitors. However, the development and design of a new car seat or interior is very time consuming and expensive. The introduction of computer models of human and seat could accelerate this process. This paper describes the application of the MADYMO human model for one aspect relating to comfort, i.e. vibrations. A validation of the multibody 50th percentile human model for vertical vibrations was performed based on volunteer experiments. The model response shows good correlation with the volunteer responses. Investigation of forces acting on the intervertebral discs shows that maximum loading appears in the lumbar spine and the lower thoracic spine.

The importance of comfort for the automotive industry is increasing. Car manufacturers use comfort to distinguish their products from their competitors. However, the development and design of a new car seat or interior is very time consuming and expensive. The introduction of computer models of human and seat could accelerate this process. This paper describes the application of the MADYMO human model for one aspect relating to comfort, i.e. vibrations. A validation of the multibody 50th percentile human model for vertical vibrations was performed based on volunteer experiments. The model response shows good correlation with the volunteer responses. Investigation of forces acting on the intervertebral discs shows that maximum loading appears in the lumbar spine and the lower thoracic spine.