Investigation of stiffness and energy absorption of variable dimension helical springs fabricated using multijet fusion technology

Recent advances in additive manufacturing (AM) have made the direct manufacturing of intricate shapes such as metamaterials and complex geometries easier, more efficient, faster, and optimally functional, as compared with the manufacturing of simple solid blocks. In this study, the authors conducted experimental investigations and simulations on the energy absorption, stiffness, and deflection of various variable dimension helical springs fabricated by a recently developed high-speed AM technology, namely, the multijet fusion (MJF) system. The variable dimension helical springs were designed by defining various parameters such as the pitch, diameter of the spring wire and spring coil, and total height of the spring. For comparison, the total masses, bounding boxes, and total heights of all samples were kept constant. The results show that the variable parameters (e.g., shape) significantly affect the properties of helical springs; therefore, the stiffness and deformation can be controlled by varying them for a particular application. Furthermore, in designing variable dimension helical springs, nonlinear force–displacement behaviors and stiffness, along with reductions in weight and maximum stresses, can be obtained. Finally, it was concluded that by optimally defining the above parameters, a spring with an ideal geometry can be designed, thereby realizing comfort, stability, and reliability, along with other application-specific benefits (e.g., lightweight).