Modern vehicles rely more and more on advanced structural components and innovative manufacturing methods to improve safety without adding unnecessary weight. Among these, additive manufacturing, the process of 3D-printing parts layer by layer, has opened new possibilities in car design.
What is Hybrid Manufacturing?
Hybrid manufacturing combines additive techniques with conventional ones (such as extrusion or high-pressure die casting). This approach leverages the best of both worlds:
- Near Net Shape and flexibility from additive methods
- Speed and strength from traditional manufacturing
The result? Lighter components with tailored mechanical properties and complex geometries that wouldn’t be possible with one method alone.
Boosting crash resistance with AVFFs
In the FlexCrash project, direct energy deposition (DED) developed by partners from Fraunhofer IWS is the additive manufacturing technique used to apply Added Value Functional Features (AVFFs) onto parts that were originally made using conventional techniques. These AVFFs act as strategic reinforcements, helping components absorb more energy in a crash without adding much weight.
Here’s how it works:
- The AVFFs are carefully shaped and placed to trigger controlled deformation, like folds, which is much more energy-efficient than uncontrolled bending.
- They also strengthen critical areas, improving how much force the part can withstand.
The layout of these features can be customized based on the crash scenario, giving designers new tools to precisely tailor safety performance
Figure 1: Traditional vs AVFF approach.
The Crash Box: a case study
One of the main applications being explored is the crash box, which is a critical component designed to absorb the energy of a collision and protect passengers.
Crash boxes are engineered to fold in predictable ways, using design elements like notches, creases, or cutouts. Within the FlexCrash project, Gemmate Technologies employs AVFFs to design these structures according to a new paradigm, guiding the deformation path and optimizing the trade-off between crashworthiness and component weight.
Crash simulation setup: realistic, repeatable, relevant
To recreate a meaningful crash scenario, Gemmate Technologies ran virtual compression tests on aluminium extruded profiles, which serve as a stand-in for a vehicle’s front crash box. These profiles were supplied by Eurecat and made from recycled 6063 T5 aluminium alloy, a common material in automotive manufacturing.
Key specs:
- Profile dimensions: 60 × 40 mm cross-section, 2 mm wall thickness
- Length: 300 mm
- Compression speed: 20 mm/ms (set by the Instron VHS160/100-20 machine)
- Duration: 8.25 ms (resulting in a 165 mm displacement)
This setup mimics how real crash boxes deform under high-speed frontal impact.
Establishing a baseline: No AVFFs
The first simulation used a plain aluminium profile with no added features. This created a baseline to compare with future designs. One end of the profile was fixed in place, while the other was compressed. The simulation tracked how energy was absorbed over time and how the material deformed.
Notably, the profile showed a folding behaviour, a controlled and efficient deformation pattern that’s highly effective at dissipating energy in frontal crashes.
Figure 2: Sketch of the mechanical setting of the simulation of the box at the initial state of the simulation (t=0 s) (a) and the computed deformation at the end of the transient (b).
What we measure: energy and force
Two main indicators help evaluate performance:
- Energy Absorbed: This is the internal energy taken up by the material as it deforms. More absorbed energy means better crash protection.
- Peak Force: The highest force the structure experiences during the crash. While high energy absorption is desirable, lower peak force can reduce the shock transferred to other vehicle parts.
The ideal design balances these two factors – strong, but not too stiff.
Advanced materials need advanced models
To simulate all this accurately, Gemmate Technologies relied on an advanced material model developed by Aerobase Innovations that includes:
- Triaxiality (how stress is distributed in all directions)
- Strain rate sensitivity (how fast a material deforms under load)
- A probabilistic failure model, which reflects real-world unpredictability in how materials break
This model was tested and calibrated using three-point bending experiments, and then used to simulate how extruded profiles with AVFFs perform in high-speed compression tests, similar to what happens in a real crash.
Thermal effects matter too
The additive process itself can change the internal structure of a part. It may introduce residual stresses, thermal distortion, or even weaken the base material. That’s why Gemmate Technologies doesn’t stop at mechanical simulations, but it combines mechanical and thermo-mechanical modelling to fully understand the effects of adding AVFFs.
This dual modelling approach was tested and calibrated using experimental data. Simulations accurately predicted not only the final geometry of printed reinforcements but also their residual stresses and mechanical behaviour. This validated approach makes it possible to confidently scale up from small test pieces to full-sized structural components.
Figure 3: Simulated deformation of the component at the end of the DED process (after the cooling).
Conclusion: a smarter way to reinforce
The FlexCrash project shows how hybrid manufacturing, guided by advanced simulation, can deliver safer and lighter vehicle components. By integrating the entire production process, additive deposition, material modelling, and crash behaviour, into a unified design approach, engineers can now create smarter structures tailored for real-world impacts.
This method not only enhances safety but also supports sustainability by optimizing material use and enabling more efficient manufacturing practices.
Authors: Gemmate Technologies
