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Abstract Skeletal fixation plates are essential components in craniomaxillofacial (CMF) reconstructive surgery to connect skeletal disunions. To ensure that these plates achieve geometric conformity to the CMF skeleton of individual patients, a pre-operative procedure involving manual plate bending is traditionally required. However, manual adjustment of the fixation plate can be time-consuming and is prone to geometric error due to the springback effect and human inspection limitations. This work represents a first step towards autonomous incremental plate bending for CMF reconstructive surgery through machine learning-enabled springback prediction and feedback bending control. Specifically, a Gaussian process is first investigated to complement the physics-based Gardiner equation to improve the accuracy of springback effect estimation, which is then incorporated into nonlinear model predictive controller to determine the optimal sequence of bending inputs to achieve geometric conformity. Evaluation using a simulated environment for bending confirms the effectiveness of the developed approach. 

This study demonstrates that the thickness of the target and its backing condition have a powerful effect on the development of a wave structure in impact welds. Conventional theories and experiments related to impact welds show that the impact angle and speed of the flyer have a controlling influence on the development of wave structure and jetting. These results imply that control of reflected stress waves can be effectively used to optimize welding conditions and expand the range of acceptable collision angle and speed for good welding. Impact welding and laser impact welding are a class of processes that can create solid-state welds, permitting the formation of strong and tough welds without the creation of significant heat affected zones, and can avoid the gross formation of intermetallic in dissimilar metal pairs. This study examined small-scale impact using a consistent launch condition for a 127 µm commercially pure titanium flyer impacted against commercially pure copper target with thicknesses between 127 µm and 1000 µm. Steel and acrylic backing layers were placed behind the target to change wave reflection characteristics. The launch conditions produced normal collision at about 900 m/s at the weld center, with decreasing impact speed and increasing angle moving toward the outer perimeter. The target thickness had a large effect on wave morphology, with the wave amplitude increasing with target thickness in both cases, peaking when target thickness is about twice flyer thickness, and then falling. The acrylic backing showed a consistently smaller unwelded central zone, indicating that impact welding is possible at a smaller angle in that case. Strength was measured in destructive tensile testing. Failure was controlled by the breakdown of the weaker of the two base metals over all thicknesses and backings. This demonstrates that laser impact welding is a robust method for joining dissimilar metals over a range of thicknesses.