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Introduction and hypothesis Several studies have assessed birth-related deformations of the levator ani muscle (LAM) and perineum on models that depicted these elements in isolation. The main aim of this study was to develop a complex female pelvic floor computational model using the finite element method to evaluate points and timing of maximum stress at the LAM and perineum in relation to the birth process. Methods A three-dimensional computational model of the female pelvic floor was created and used to simulate vaginal birth based on data from previously described real-life MRI scans. We developed three models: model A (LAM without perineum); model B (perineum without LAM); model C (a combined model with both structures). Results The maximum stress in the LAM was achieved when the vertex was 9 cm below the ischial spines and measured 37.3 MPa in model A and 88.7 MPa in model C. The maximum stress in the perineum occurred at the time of distension by the suboocipito-frontal diameter and reached 86.7 MPa and 119.6 MPa in models B and C, respectively, while the stress in the posterior fourchette caused by the suboccipito-bregmatic diameter measured 36.9 MPa for model B and 39.8 MPa for model C. Conclusions Including perineal structures in a computational birth model simulation affects the level of stress at the LAM. The maximum stress at the LAM and perineum seems to occur when the head is lower than previously anticipated.

"Current trends in mobility bring new challenges for both active and passive safety. Although connected and highly automated vehicles shall be impact-free due to the common communication, safe co-existence between automated and non-automated conventional traffic for a long transition period of mixed traffic must be ensured. Current approaches for vehicle certification process involves the mechanical dummies, which are usually limited to a single direction impact assessment. Virtual human body models bridge the gap enabling assessment in multi-directional impact scenarios. Different human body models have been already implemented for safety assessment in high-speed impacts, however, low-speed impact scenarios are also necessary to be addressed. The main aim of this work is to show the biofidelity of the virtual human body model Virthuman in the low-speed crash scenario. The exploited hybrid scalable virtual human body model Virthuman is formed by the skeleton as a multi-body structure coupled to deformable segments representing the outer skin. Thus, the model can be simply adapted to any initial position in the virtual environment for the fast calculation process for injury risk prediction. The model is scalable, so it is simply able to represent a human subject of the given age and posture. The special sled test device is used in the experimental measurement with the human volunteer and four-times with the Hybrid III dummy to simulate the low-speed impact. The low-speed impact scenario is numerically simulated using the finite element model of the Hybrid III dummy as well as with the hybrid Virthuman model. The simulation with the finite element Hybrid III is firstly used for the proper definition and validation of the seat belt model, which will be further used also in the simulation with the Virthuman model. The biodelity of the Virthuman model compared to the biodelity of the physical Hybrid III dummy is tested via objective correlation and analysis (CORA) method. The results show that the human body model performs better real human body behaviour than the dummy model in the low-speed impact. The presented work summarizes a possible approach towards virtual prototyping of safe interior concepts in the automated driving era. Acknowledgement: The work was supported by the European Regional Development Fund-Project Application of Modern Technologies in Medicine and Industry” (No. CZ.02.1.01/0.0/0.0/17_048/0007280) and by the internal research grant SGS-2019-002. Special thanks belong to BESIP providing the low-speed sled test environment and ŠKODA Auto a.s. for providing the infrastructure and the dummy."

Virtual human body models contribute to designing safe and user-friendly products through virtual prototyping. Anthropometric biomechanical models address different physiques using average dimensions. In designing, e.g., personal protective equipment, orthopedic tools, or vehicle safety systems, biomechanical models with the correct geometry and shape shall play a role. The presented study shows the variations of subject-specific anthropometric dimensions from the average of the different population groups in the Czech Republic and China as a background for the need for personalized human body models. The study measures a set of dimensions used to design clothing patterns of Czech children, Czech adolescents, Czech adults, and Chinese adults and compares them to the corresponding age average, which is represented by a scaled anthropometric human body model. The cumulative variation of the dimensions used to design the clothing patterns increases the further the population group is from the average. It is smallest for the Czech adults at 7.54 ± 6.63%; Czech adolescents report 7.93 ± 6.25%; Czech children differ be 9.52 ± 6.08%. Chinese adults report 10.86 ± 11.11%. The variations from the average of the particular dimensions used to design clothing patterns prove the necessity of having personalized subject-specific models. The measured dimensions used to design the clothing patterns serve as the personalization of particular body segments and lead to a subject-specific virtual model. The developed personalization algorithm results in the continuous body surface desired for contact applications for assessing body behavior and injury risk under impact loading.