AddiFlex is an innovative company from Slovenia, located in Ravne na Koroškem, just a stone’s throw from the Austrian border. The company focuses on development and manufacturing using advanced technologies and 3D printing solutions. It specializes in creating products from high-quality flexible and rigid materials, enabling a wide range of applications across various industries and fields. AddiFlex has quickly established itself on the market with its unique approach and adaptable solutions tailored to the needs of companies and individuals in different sectors.
The story of AddiFlex began with a vision to accelerate and simplify product development through advanced 3D printing technologies. The company chose to focus on flexible and specialized 3D printing materials that support easier prototyping and the production of functional parts suitable for diverse industries such as automotive, medical, consumer electronics, and many others.
The company places strong emphasis on sustainability and local production, with all components manufactured in the broader Ravne na Koroškem area.
Development of an advanced cellular armrest in collaboration with the IPD CAD Lab FS MB
In close collaboration with the IPD CAD Lab FS MB (Laboratory for Integrated Product Development and CAD Faculty of Mechanical Engineering in Maribor) we developed the first ergonomic armrest featuring a cellular structure. The geometry of the armrest was designed with the following key criteria in mind:
• Optimal fit to the user’s arm through a dual-curvature profile.
• Variable radius along the contact edge for a softer and more comfortable support.
• Symmetrical cushion shape in both longitudinal and transverse directions, enabling versatile use.
The cellular structure itself ensures breathability, comfort, and a lightweight design.
Based on the testing results of the first 3D-printed prototypes, the initial topological–geometric correction of the armrest was carried out, defining the dimensional–topological framework of the cushion and consequently also of the base, in order to achieve an optimal biomechanical response.
This was followed by the development of a biomechanical numerical model to adjust the properties of the ergonomic armrest.
Development of a biomechanical numerical model of the arm to improve the properties of the cellular armrest.
The basic geometry of the arm was created based on a CT scan that captured soft tissues as well as the radius and ulna bones. In the numerical simulation, all soft tissues were merged into a single part, which allowed for simplification of the model and optimization of computational processing.
Since the palm was not in contact with the armrest during the simulation and was treated as a rigid body, the bones of the hand were not included in the geometric model of the arm. The position of the arm and bones was adjusted to simulate the use of the cellular armrest while working with a desktop computer mouse.
Transparent views of the arm model illustrate the position of the radius and ulna bones within the soft tissue and their relationship to the armrest. The bones were anthropometrically adjusted to a position that corresponds to the use of a computer mouse. Ensuring the correct positioning is crucial, as the thickness of the soft tissue layer between the bone and the armrest significantly affects the distribution and magnitude of contact pressure.
In the analysis of biomechanical systems, such as the simulation of interaction between the arm and the armrest, two key parameters are commonly used: contact pressure and displacement. These were carefully considered during the product development process. Contact pressure is directly related to comfort, as excessive pressure values or high concentrations can lead to discomfort or even soft tissue damage.
On the other hand, displacement is used to evaluate the stability of the analyzed component. The maximum contact pressure and its distribution were analyzed at the interface between the cushion and the arm. Vertical displacement of the cushion is presented in cross-section.
For the purpose of mechanical testing, the geometry was defined according to ISO 3386-1:1996, using open and closed cylindrical samples with a diameter of 60 mm and a thickness of 15 mm. In total, more than 40 different samples were tested throughout the project, featuring various ligament thicknesses, cell diameters, and open or closed structures.
The thickness of the samples was primarily based on the proposed cushion thickness, as increasing the thickness also increases the number of base cells along the height, which in turn affects the mechanical response of the structure.
Based on all conducted analyses and experimental tests, we developed the final cushion geometry that fully meets the initial project requirements. A key factor was the implementation of functional gradation in cell size, which enabled an optimal balance between mechanical response, stability, and user comfort.
A softer response was achieved in the central part of the cushion to provide greater comfort, while the stiffer outer regions ensured the necessary support.
