The finite element method (FEM) has deservedly gained the reputation of the most powerful, highly efficient, and versatile numerical method in the field of structural analysis. Though typical application of FE programs implies the so-called “off-line” computations, the rapid pace of hardware development over the past couple of decades was the major impetus for numerous researchers to consider the possibility of real-time simulation based on FE models. Limitations of available hardware components in various phases of developments demanded remarkable innovativeness in the quest for suitable solutions to the challenge. Different approaches have been proposed depending on the demands of the specific field of application. Though it is still a relatively young field of work in global terms, an immense amount of work has already been done calling for a representative survey. This paper aims to provide such a survey, which of course cannot be exhaustive.

Background: Track noise is one of the main issues in the development of railway networks. It is well known that rail dampers, as a cost-effective, passive means of vibration reduction, do reduce the noise; still, neither the mechanism behind their action nor the influential parameters are well understood. Purpose: The main purpose of this work is to investigate the efficiency and influential parameters of a rail damper design based on a lab-scaled model of the rail-damper system and an accurate FE model. Methods: Based on experimental and numerical modal analyses and the Modal Assurance Criteria (MAC) analysis, the FE model updating technique was applied to develop a highly accurate FE model of the rail-damper system for the investigated frequency range. In a further step, the developed FE model is used in a parametric analysis to assess various damper parameters with respect to the efficiency of damping rail vibrations and, therewith, radiated noise. Results: The investigation performed based on FE simulations demonstrates how different material and geometric parameters of the damper influence the mobility decay rate of rail vertical vibrations. The investigated parameters are the thickness of still and rubber layers, stiffness and damping loss factor of rubber layers, and pre-force in the bolts that press the layers together. Conclusions: It is shown that the FE model updating technique was capable of producing a highly accurate FE model despite the challenging properties of the real structure and that a combination of the lab-scaled model and the FE model represents a cost-effective approach.

Selection of boundary constraints may influence amount and distribution of loads. The purpose of this study is to analyze the potential of inertia relief and follower load to maintain the effects of musculoskeletal loads even under large deflections in patient specific finite element models of intact or fractured bone compared to empiric boundary constraints which have been shown to lead to physiological displacements and surface strains. The goal is to elucidate the use of boundary conditions in strain analyses of bones. Finite element models of the intact femur and a model of clinically relevant fracture stabilization by locking plate fixation were analyzed with normal walking loading conditions for different boundary conditions, specifically re-balanced loading, inertia relief and follower load. Peak principal cortex surface strains for different boundary conditions are consistent (maximum deviation 13.7%) except for inertia relief without force balancing (maximum deviation 108.4%). Influence of follower load on displacements increases with higher deflection in fracture model (from 3% to 7% for force balanced model). For load balanced models, follower load had only minor influence, though the effect increases strongly with higher deflection. Conventional constraints of fixed nodes in space should be carefully reconsidered because their type and position are challenging to justify and for their potential to introduce relevant non-physiological reaction forces. Inertia relief provides an alternative method which yields physiological strain results.

Structural analysis, based on the finite element method, and structural optimization, can help surgery planning or decrease the probability of fixator failure during bone healing. Structural optimization implies the creation of many finite element model instances, usually built using a computer-aided design (CAD) model of the bone-fixator assembly. The three most important features of such CAD models are: parameterization, robustness and bidirectional associativity with finite elements (FE) models. Their significance increases with the increase in the complexity of the modeled fixator. The aim of this study was to define an automated procedure for the configuration and placement of fixators used in the treatment of long bone fractures. Automated and robust positioning of the selfdynamisable internal fixator on the femur was achieved and sensitivity analysis of fixator stress on the change of major design parameters was performed. The application of the proposed methodology is considered to be beneficial in the preparation of CAD models for automated structural optimization procedures used in long bone fixation.

From the economic and technical point of view, the reduction of development periods and required resources represent a considerable benefit. For the reduction of numerical effort and processed data in numerical stress analysis, the present paper is focused onto the investigation of an efficient method for the a priori detection of a structural component's highly stressed areas. Based on the theory of stress mode superposition and the frequency domain solution of the decoupled equations of motion, an analytically consistent approach for a priori mode superposition is presented. In this context, the influence of multiaxial loading and mode normalisation is investigated. Validation is performed on a simplified industrial model of a twist-beam rear axle.