A particular challenge in the vehicle development is the analysis and prognosis of vibrational seat comfort. Besides the complexity of load cases with varying amplitudes and the setup of vehicle dynamics, a realistic representation of the human body is the main challenge. Many human body models are created for static load cases and therefore are limited in their application to dynamic analyses. The finite element human body model CASIMIR was developed in the 90s at the Technical University Darmstadt. The model was used for the computation of loads acting on the lumbar spine because of vibrations in working environments. Accordingly, the main request for the model setup was the correct representation of the dynamic behavior of the human body. Within the last years, the CASIMIR was improved by a more detailed setup and anthropometric variations (different percentiles). Furthermore, an interface to the ergonomic package of RAMSIS was generated, enabling communication between the departments of seat development and ergonomics. Finally, numerical methods were developed to integrate the human body model in NVH and the ride comfort analysis of the complete vehicle. The chapter presents firstly the general setup of the human body model and its validation with respect to dynamic behavior. Then, the simulation process of seat vibrations is described focusing on the relevant factors. Finally, the procedure to implement an occupied seat within a vehicle analysis is described, and exemplary results are presented.

Since 9/11, the crash of a commercial aeroplane on the reactor building of a nuclear power plant is a realistic design scenario. Before that the structural behaviour under a crash of a military plane was investigated by a procedure using load-time-functions (Riera, 1968). Thereby, the computation of the load-time-function was based on a conceptional model considering the main stiffness parts and masses by discrete elements. With respect to the homogeneous structural set-up of a military plane, the application of this model and the derived load-time-function applied as lumped load case seems very feasible. Contrary thereto the structural set-up of a commercial aeroplane, with e.g. the high mass concentration of the turbine or the high stiffness of the wing box compared to other parts, is different. This can be counteracted by using a more detailed finite element (FE) model for the computation of the load-time-function and by dividing the load case for the reactor building in different main load zones.Although this represents a more detailed investigation, the procedure of using a load-time-function still has the disadvantage to separate the real scenario into two steps. Thereby, the direct interaction between the structure and the aeroplane including all softening effects due to material respectively structural compliances is neglected. This leads to the general conclusion that by applying load-time-functions the results are conservative compared to the real behaviour.Due to the increased capabilities of numerical software solutions it is also possible nowadays to carry out integral crash simulations, combining all effects within one simulation. Compared to the procedure of using load-time-functions, the numerical complexity and therefore the amount of work for this integral method are increased.Within this paper both procedures (load-time function by detailed FE-model and the integral method) are exemplarily compared to each other by a crash analysis of an Airbus type A320 with different velocities (80, 120 and 160 m/s) on simplified reactor building. The final evaluation is carried out by the maximum displacement of the reinforced concrete reactor building wall being a criterion for the integrity of the building. With respect to the results it could be shown, that the procedure using load-time-functions has limitations for the investigation of some scenarios. This could finally lead to the decision that for the design process of new nuclear power plants the application of the integral method comprehends advantages that justify the additional efforts. (C) 2013 Elsevier B.V. All rights reserved.

A particular challenge in the development of passenger cars by means of numerical simulation consists in the prognosis of the vibration comfort of the passenger. Reason for this are the nonlinear and frequency-dependent properties of human body and seat. The integration of the occupied seat in the complete passenger car is principally feasible, but increases the computational efforts for NVH-analyses dramatically. Reason for this is the nonlinear seating process which must be calculated for the determination of the operating point prior to the actual NVH-analysis. As a workaround a simplified method was developed. In a first step a separate analysis of the occupied seat is performed with the tool CASIMIR/Automotive. After that the systems is condensed to the relevant degrees of freedom in the form of a matrix. The integration in the complete passenger car is realized via the connections at the real coupling points, i.e. via seat rail, feet and hands. For the direct evaluation in the complete passenger car the matrix includes further output points, e.g. head and torso. A detailed visual evaluation of individual operating vibrations can be carried out subsequently in the post-processor by the direct combination of the simulation of the complete passenger car and the occupied seat. The developed method was applied and validated within the scope of a pilot project. Compared to existing methods this new approach offers additional information content, since all relevant components can be simulated already at an early stage so that statements as to the vibration comfort and possible hardware optimizations can be made.

Finite element (FE) models of the human body are applied in a wide range of scientific and industrial investigations. Due to continuously improving software and hardware capabilities the model detailing is increasing step by step. A major challenge of this evolution is the realistic representation of soft tissues. Thereby, the modelling of the skeletal muscles causes particular requirements as the active filamentary force transmission has to be coupled with the passive volumetric behaviour. The work here presented describes the latest development for the human body model CASIMIR, including an enhanced approach of the tissues in the buttock and the thighs. In a first step, the passive and active properties are identified separately for skeletal muscle tissue and implemented via a discrete and volumetric model formulation. Validating the coupling of both material parts in a simplified setup, an investigation on an isolated muscle is carried out. Finally, the invented modelling technique is integrated in CASIMIR and used to investigate the influence of the thigh hamstrings muscle activity on the seat pressure distribution.

Background and purpose The aim of this study was to compare MRI-based morphological gross tumour volumes (GTVs) to biological tumour volumes (BTVs), defined by the pathological radiotracer uptake in positron emission tomography (PET) imaging with 18F-fluoroethyltyrosine (FET), subsequently clinical target volumes (CTVs) and finally planning target volumes (PTVs) for radiotherapy planning of glioblastoma. Patients and methods Seventeen patients with glioblastoma were included into a retrospective protocol. Treatment-planning was performed using clinical target volume (CTV = BTV + 20 mm or CTV = GTV + 20 mm + inclusion of the edema) and planning target volume (PTV = CTV + 5 mm). Image fusion and target volume delineation were performed with OTP-Masterplan®. Initial gross tumour volume (GTV) definition was based on MRI data only or FET–PET data only (BTV), secondarily both data sets were used to define a common CTV. Results FET based BTVs (median 43.9 cm3) were larger than corresponding GTVs (median 34.1 cm3, p = 0.028), in 11 of 17 cases there were major differences between GTV/BTV. To evaluate the conformity of both planning methods, the index (CTVMRT ∩ CTVFET)/(CTVMRT ∪ CTVFET) was quantified which was significantly different from 1 (0.73 ± 0.03, p < 0.001). Conclusion With FET–PET-CT planning, the size and geometrical location of GTVs/BTVs differed in a majority of patients. It remains open whether FET–PET-based target definition has a relevant clinical impact for treatment planning.

Even though stereotactic brachytherapy has been used for treatment of complex located low-grade glioma for many years, its place within modern treatment concepts is still debated and only a few centers have gained experience with this complex treatment modality. The current article reviews selection criteria, treatment protocols, radiobiology, treatment effects, risk models and side effects of stereotactic brachytherapy. Potentially alternative techniques such as radiosurgery were also reviewed under consideration of radiobiological similarities and differences.

Nowadays low back pain is beneath the population one of the most common and significant musculoskeletal problems. The causes as e.g. reduced body motion or loads out of the daily work life are versatile. The medical handling ranges form physiotherapies up to spine surgeries replacing intervertebral discs with implants. Through the fact, that more and more young people are affected and that the lifestyle of older people is changing, the requirements of the implants are steadily increasing.For new implant designs the application of numerical simulations has a decisive role as it enables in combination with optimization algorithms a target-oriented development. While the final optimization is carried out on sub-models, the computation of adequate loads is done by applying human body models, representing the static and dynamic properties in detail. The human body model CASIMIR, presented here, was used in different investigations where a good correlation to measurements of static and dynamic quantities was found.In order to increase the accuracy of these occupant results, CASIMIR was enhanced by a detailed buttock and thigh model, to improve the force transmission to the lumbar spine. In the first model setup the muscle tissue properties have been separated into two parts: a continuum model (3D), representing the passive tissue behaviour, and a discrete model (1D) with springs and dampers for the filamentary force transmission of muscle contraction.In the second model setup a combination of the active and passive tissue behaviours was investigated. Thereby it was shown by a simulation with an idealized muscle that an interaction of both parts is possible, i.e. an active contraction goes along with an increased stiffness of the compressive behaviour.The paper, presented here, describes the different parts of the model setup, the simulation and the results of both setups.

For the evaluation of seats under comfort and health aspects by means of a Finite-Element (FE) simulation a detailed static and dynamic occupant model is required. The occupant model CASIMIR, which is presented here, in combination with seat model was used in different comfort simulation projects where a good correlation to measurements - seat pressure distribution and transfer function - was found.In order to increase the accuracy of results for internal quantities e.g. the load on the intervertebral disks, CASIMIR was enhanced to improve the force transmission from the seat to the human body. Due to the consideration of the different tissues by corresponding material parameters and the modelling of the filamentary force transmission via springs and dampers for muscles, the human anatomy is modelled more realistically.