3D printing a defect-free bike bottom lug component

An increasing number of industries are embracing additive manufacturing to complement and replace traditional manufacturing technologies. The high-end, custom sports equipment industry – specifically the bicycle industry – is one of the relatively new (compared to aerospace, for example) adopters of the technology. A recent case study is that of Ansys Additive Simulation partnering with Aconity3D to print a defect-free bike bottom lug component.

A fully 3D printed bike

At Brightlands Chemelot Campus, one of the four campuses of an open innovation community located in the province of Limburg, Netherlands, designers, researchers, and engineers have collaborated to create a fully 3D printed racing bike that meets the high-performance, light-weight, and customisability demands – while still maintaining great durability and strength for unpredictable road conditions. To achieve this, they used various high-performance materials and additive manufacturing technologies to create a lightweight, durable, and highly tailored bicycle frame.

The bottom lug, which connects different bike frame segments, is a critical component in the bike’s design. To manufacture this component, Brightlands worked with Aconity3D GmbH, an industry-leading machine manufacturer and additive manufacturing solution provider for the laser-based 3D printing of metals, located in Aachen, Germany.

Ti-6Al-4V was chosen as the printing material, to ensure the custom-designed bike bottom lug is strong enough to endure harsh conditions, while still being lightweight. This material is known for its superior specific strength, and is widely used in aerospace and medical applications.

During the printing process, the bike bottom lug was oriented as shown above, and a series of generated support structures were used where needed. An AconityMIDI+ laser powder bed fusion (LPBF) system was used to perform the print, at Aconity3D GmbH. Although the bike component printed fairly well, there was an unexpected issue.

Delamination challenges

Due to high strain accumulation effects, critical delaminations occurred at the interfaces between the as-built bottom lug part and the support structures. Such delamination typically occurs when strain at that location exceeds the elongation a material can withstand. As a result, the support structures were unable to effectively constrain the deformations of the as-built part, which could potentially lead to issues with geometrical tolerances.

Ansys Additive’s high-strain detection

To solve this support structure delamination defect, Ansys and Aconity3D partnered by integrating additive manufacturing process simulations into the manufacturing workflow. Ansys Additive LPBF simulations were used to quickly identify the critical areas and evaluate build orientation and support strategies. The LPBF simulation high-strain result tool highlights critical strain regions, which enables engineers to identify regions of the part that may be prone to forming cracks during or after the build. Based on the simulation results, an optimized strategy was implemented for the physical validation print in an Aconity MIDI+ LPBF system.

First, an inherent strain static structural model was used for simulating the build setup with the exact build orientations and support structures from the defective build. The high strain feature was added to the simulation result section to detect the critical regions with high strain accumulation during the printing process.

Upon reviewing the simulation results, the identified high-strain regions closely matched the locations where delaminations occurred during the actual build. These areas would likely serve as the initiation sites for delamination, which would then rapidly propagate through the adjacent interface between the bottom lug part and support structures.

By conducting a simulation evaluation of the first print build, the high strain detection feature from Ansys Additive simulation was shown to successfully deliver high-fidelity mapping to the critical areas that were observed and verified in the physical build.

The next step involved enhancing the build orientation and support structures to prevent delamination defects. To achieve this, Aconity3D’s engineers collaborated with Ansys Additive simulation before proceeding with the next physical build.

The result

Based on the outcomes from the previous build, the AconityMIDI+ produced a great component, even though the high-strain occurred at the interface between the part and supports, causing delaminations. To print it even better, Aconity3D’s engineers revised the build orientations and strengthened the support structures in crucial areas. Instead of directly printing the next build, they teamed up with Ansys to perform a preliminary simulation with high strain detection enabled for the new build setup. The simulation results indicated a significant reduction in high-strain regions along the interface between the newly oriented bottom lug part and the support structures, in comparison to the previous build setup.

By embedding process simulations into Aconity3D’s manufacturing workflow, process engineers can easily evaluate and validate different orientation and support strategies in simulation – before sending the build files to the machine floor. Therefore, the successful integration of simulation increases efficiency and reduces time and cost by reducing the number of test prints.

The success of the collaboration between Ansys and Aconity3D has realized the perfect printing of the bottom lug component. Once the component was assembled onto the racing bike, the bike was taken for a test ride – and performed exceptionally well.