Impact Simulation of Composite Structures

Applications of Composite Materials in impact-relevant use-cases

Highly dynamic events in aviation

The use of carbon fiber reinforced plastics (CFRP) has steadily increased in civil and military aviation. The lightweight fiber composite construction not only enables a reduction in overall weight, but also leads to lower energy consumption and an increased range.

At the same time, the aviation industry and safety authorities place high demands on the crashworthiness of aircraft. These include extensive tests such as bird strike tests, the simulation of engine damage (e.g. fan blade-off) and ground impact simulations. The ability to accurately simulate these tests is a core capability of CIKONI that helps to ensure safety and reliability in aviation.

Bulletproof vests and other ballistic protection systems

Another important area of application for FRP is ballistic protection systems such as bulletproof vests and vehicle armor. Hybrid armor systems that use FRP in combination with metals and ceramics are often used.

These material combinations not only offer optimum protection, but also contribute to weight savings. The development of these systems requires in-depth knowledge of all the materials used and their behavior under different impact scenarios. High-performance overall systems can be developed by utilizing the material-specific advantages.

High-pressure tanks for CNG and hydrogen under short-term dynamic loads

In the automotive industry, CFRP and GFRP are increasingly being used in type 3, type 4 and type 5 high-pressure storage tanks, especially for hydrogen applications. These designs significantly reduce weight and improve efficiency. At the same time, these tanks must be robust enough to provide the necessary protection in the event of accidents or other impacts. Puncture tests and simulations of crash loads or firing scenarios are essential to ensure the safety and reliability of these systems.

Materials used for impact loads

Energy-absorbing reinforcing fibers

When selecting fibers, materials such as carbon fibers, S-2 glass, Kevlar® and polyethylene are used. Each fiber has its specific advantages and disadvantages, which significantly influence the mechanism and behavior of the FRP. S-2 glass, for example, offers high strength at an attractive cost, while Kevlar® has excellent impact strength. The selection of suitable fiber systems or their combination can only be determined by an in-depth understanding of customer requirements and the use of simulative models.

Thermoset and thermoplastic matrix systems

The choice of matrix material is critical to the performance of impact loaded FRP structures. Thermosets offer high heat resistance and chemical stability, while thermoplastic matrix systems score points for their toughness in energy absorption. The choice of the right system depends on the specific requirements of the application and is determined by CIKONI on a customer-specific basis for the respective application.

Combined advantages: Hybrid systems

Hybrid systems that integrate metallic materials, oxide ceramic materials or silicon carbide combine the advantages of different materials. These systems are particularly suitable for optimizing the mechanisms of material failure and improving performance under impact conditions at optimal cost.

Challenges in the development of impact-loaded structures and the simulation of impact processes

The simulation of impact processes in fiber-reinforced composites presents engineers with a variety of challenges. One of the biggest challenges is the correct modeling of the short-term dynamics at hand, which requires precise availability of material data. Material parameters need to be carefully calibrated and are highly dependent on the manufacturing processes used. Another critical aspect is the directional dependence of the material properties, which influences the failure behavior under impact. Understanding the dependencies on temperature and other environmental influences is of central importance.

This also includes the need for multi-scale simulation in order to map the different levels of material interaction during an impact. In addition, standards and legal framework conditions that are relevant for the respective applications must be taken into account.

CIKONI’s approach to the development of impact structures and the simulation of impact processes in composites

CIKONI takes a holistic approach to the simulation of impact processes in fiber-reinforced composites. Our team of fiber composite experts brings in comprehensive domain knowledge from areas such as material selection, material characterization, design, FEA simulation, testing, manufacturing and joining technology. By using adapted analytical models and simulations suitable for fiber composites, we ensure that the specific properties of composites are fully taken into account.

In addition, we integrate anisotropy, manufacturing influences, strain rate dependency and temperature effects into our simulations. The use of macro and meso models enables a detailed analysis and optimization of the materials, resulting in high-performance systems that extend from the design stage through simulation to series production.

In detail, the FEM calculation raises the question of the required and at the same time project-side required accuracy in the modeling of the component under consideration. Our aim is to maximize the efficiency of the calculation and project implementation while at the same time achieving a high prediction quality for the problem under consideration.

In addition to the layer properties, interlaminar energy release rates are also of great importance for the modeling of delamination in the material data for impact and ballistic events. The experimentally determined material properties are implemented and validated by CIKONI engineers in material cards for the FEM calculation.

Our expertise in different FE solvers is crucial, as the material models for composites sometimes differ significantly. We routinely use LS-Dyna, PAM-Crash, Radioss or Abaqus for dynamic simulation.

Special issues arise in FEA of impact in the case of particularly thick-walled laminates, such as those commonly used in pressure tanks for hydrogen storage. The temperature development in the impact area and the resulting change in material properties can become relevant. The same applies to the question of the permissibleburst pressureafter an impact load (residual burst pressure after impact). We are happy to look at these and other topics for you in the impact and ballistic simulation.

CIKONI: Your solution provider in the field of dynamically loaded structures

Safety and efficiency are coming to the fore in many industries. Fiber composites offer the possibility of developing high-performance structures that combine lightweight construction and high energy absorption capacity. CIKONI offers its customers innovative solutions for the simulation of impact processes in fiber composite components. Our approach combines extensive experience, technological innovation and a strong partner network to meet our customers’ requirements and drive forward pioneering developments in the industry.

We see ourselves not only as a traditional provider of engineering services, but can also offer complete solutions from conception to series production thanks to our manufacturing and machine resources.