Motivated by the necessity of validating new materials for future turbines, a set of Blade Crush Tests have been performed with Inconel 713 blades, TiAl blades, Inconel 718 casing material and steel plates. The objective of these tests is to study separately the deformation of a blade during a containment event (configuration 1 tests), and the damage of the casing caused by the impact of different blades (configuration 2 tests). The results of these tests are validated with LS-Dyna analysis, providing a reliable tool for predicting the containment capability of the casings and the out of balance progression in a blade off event. This will allow to assess the containment capability of future designs without the need of large and very costly test campaigns or service experience.
This paper presents a study on AA6016 plates in temper T4 subjected to blast loading. Four different crack-like defects have been introduced in the plates to facilitate crack propagation as the dominating failure mode. Uniaxial tensile specimens extracted from a plate are used in the calibration of the *MAT_258 material model available in LS-DYNA. This material model contains a non-quadratic yield surface, isotropic work hardening and a failure model where the onset of failure is dependent on the element size as well as its bending-to-membrane loading ratio. Four different element sizes are investigated to assess the ability of the model to predict the onset of failure and subsequent crack propagation in blast-loaded plates by comparison to experiments conducted in a shock tube facility.
A substantial number of debris coming from human production gravitates around the Earth. Their size, nature, orbit and velocity can extremely vary, but all these debris represent an increasing collision risk and a threat for the current and future spatial activity. The spatial researchers are looking for solutions to limit this risk, by better controlling the launched objects number and by improving the protection of their structures.
Impact loading is a safety relevant loading case for reinforced concrete structures used to protect vital parts of nuclear facilities. Numerical methods used for the assessment are validated on the basis of impact tests. Even though normal impacts are the most common item of analysis, special issues are related to inclined impact. Effects of inclined impact include slipping and rotation of the missile, motion of the impact point and effects of tangential forces. Recently, an experimental program dealing with bending failure of reinforced concrete slabs subjected to inclined soft missile impact was carried out at Technical Research Centre of Finland (VTT) in the frame of phase IV of the international research project IMPACT. This paper reports on simulation results on these tests using LS-DYNA.
Failure of rotating machinery in nuclear power stations may result in ejection of fragments with high kinetic energy. Pieces of the disk or blades of a damaged turbine may cause failure of surrounding systems, structures, and components. The current paper presents study of effect of turbine disk fragment ejected as hard missile on the capacity of the protective walls of safety-related nuclear building. The investigation is performed by the missile-target interaction method, i.e. impact simulation of the model of the missile (i.e. the disk fragment) into the model of the protective barrier. Detailed model of the target is generated utilising non-linear material models for rebar steel and concrete. Different scenarios are investigated to define the most unfavourable impact with respect to the protective capacity of the safety barrier. The acceptance criteria are adopted form the relevant international regulatory documents. Special emphasis is given to the hourglass reduction. Various options are studied such as the hourglass control keywords, mesh refinement and different element formulation. The outcome in terms of CPU time and fulfilment of the structural acceptance criteria is compared and conclusions are drawn.
Railway transportation represents an environmentally friendly alternative to automotive transportation for long distance travel. In the project Next Generation Train of the DLR, new railway solutions are developed for passenger and freight transportation for a broad range of applications (intercity, cargo, long distance). Specifically, the high-speed train NGT HST aims at reducing travel times and specific energy consumption with new technologies. At the maximal operating speed of 400 km/h, the coupling of mechanical and aerodynamical forces leads to increasing risks of ballast stone impact on the train structures (in particular underbody structures), thus threatening primary components underneath [1]. Through the repetition of stone impacts during the entire lifetime of a structure, critical damage can occur and reparation or replacement concepts are required. The present work aims at investigating an impact-resistant underbody structure made out thermoplastic composite materials for the HST train on numerical and experimental basis. By considering multiple impact scenario in the structure sizing process, the project intends to reduce the interval at which the structure has to be replaced.
In a typical satellite bus, most impact-sensitive equipment is situated in the enclosure of the structural sandwich panels, often – panels with a honeycomb core (honeycomb-core sandwich panels, HCSPs). As commonly used elements in satellite structures, these panels form the satellite’s shape and are primarily designed to resist launching loads and provide attachment p oints for satellite subsystems [1]. With low additional weight penalties, their intrinsic ballistic performance can often be upgraded to the level required for orbital debris protection [2].
In a typical satellite bus, most impact-sensitive equipment is situated in the enclosure of the structural sandwich panels. Being the most commonly used elements of satellite structures, these panels form the satellite’s shape and are primarily designed to resist launching loads and provide attachment points for satellite subsystems [1]. With low additional weight penalties, their intrinsic ballistic performance can often be upgraded to the level required for orbital debris protection [ 2]. Consequently, assessing the orbital debris impact survivability of satellites requires the availability of predictive techniques and hypervelocity impact (HVI) simulation models for sandwich panels, which are capable of accounting for various impact conditions and design parameters.
Orbital debris is an increasing threat to current and future missions in low Earth orbit (LEO), and spacecraft shielding is vital for future space exploration efforts. Experimental hypervelocity impacts (HVI) are expensive and can only be performed at a few laboratories worldwide, making numerical simulations an essential tool in the development and design of debris shields. A debris shield is a sacrificial plate that shatters an impactor into a cloud of particles, distributing the momentum of the impactor over a large area, thus preventing it from perforating the spacecraft. In this study, HVI were modelled in LS-DYNA using a coupled finite element-discrete particle method (FEM/DES), through the *DEFINE_ADAPTIVE_SOLID_TO_DES keyword. The results were compared to experimental data from the literature as well as to simulations applying the smoothed particle hydrodynamics (SPH) method. First, impacts by projectiles with diameter below 1 cm and impact velocities up to 6.7 km/s were simulated to study the debris cloud after perforation of a single plate. Here, aluminium alloy AA6061-T6 was used as both the target and the projectile material. The FEM/DES method was able to predict the shape of the debris cloud as a function of impactor shape, impactor velocity and shield thickness. Then, the FEM/DES method was applied to a dual-wall Whipple shield configuration and was able to accurately describe the damage from the debris cloud on the rear wall.
Data and simulation results presented by Teland et al. (2018) for incident and reflected pressure histories indicated the simulation results time of arrival and pressure magnitude did not agree well with the data for the reflected shock. They posited three possibilities for the differences: (1) Charge load (explosive mass per chamber volume), (2) Afterburning and (3) Variable Gamma for the gas mixture.
Inconel 713 and TiAl turbine blade impact test validation with LS-Dyna, including Inconel 718 casing and failure models