2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Geometrical Issues and Final Part Characterization
Program Organizers: David Leigh, University of Texas at Austin
Monday 1:30 PM
August 3, 2026
Room: Lavaca
Location: AT&T Center
1:30 PM
A Framework for Distortion Risk Prediction in Laser Powder Bed Fusion: Bradley Jared1; Nathaniel Hall1; 1University of Tennessee, Knoxville
A prominent barrier to part qualification in laser powder bed fusion is part distortion. To combat distortion, various techniques including both modeling and in-situ sensing have been implemented. Such techniques are often computationally expensive and therefore reduce the scale at which meaningful analysis can occur in reasonable time. In the following work, rapid part scale simulations are accomplished in a two-step process. First, the layer-wise thermal state of a part is determined either by a reduced order lumped capacitance model or by infrared sensing. The thermal state is used to inform an analytical heat transfer model capable of outputting a discretized map of layer-wise solidification data. The data is then used to create a distortion risk indicator calculated for each layer. The work yields a workflow for both a priori simulation and in-situ informed simulation. The behavior of the risk indicator is demonstrated on parts with varying magnitudes of distortion.
1:50 PM
Experimental Assessment of Geometrical Quality in Fused Filament Fabrication Using an In-Process Annealing System: Rakin Ahmed1; Tanvir Ahmed Shanto1; Md Mahmudur Rahman1; Sakib Ahmed1; Israt Sharmin Dola1; Sarah Binte Hossen1; Jasraj Singh1; Robert M Taylor1; 1University of Texas at Arlington
Thin-walled stiffened structures fabricated using Fused Filament Fabrication (FFF) are highly susceptible to geometrical distortion due to thermal gradients, residual stresses, and non-uniform cooling behavior associated with deposition paths and thin-walled geometries. While auxiliary heating or in-process annealing approaches have previously demonstrated improvements in interlayer bonding and mechanical performance of FFF components, limited research has explored their influence on geometrical accuracy and dimensional stability in complex stiffened structures. This study experimentally investigates the effect of a patented annealing-enabled printhead on the dimensional accuracy of thin-walled stiffened cylinders. Specimens were fabricated using both conventional and in-process annealing-enabled printheads while systematically varying print speed and seam alignment strategy (random and sharp corner) to alter the thermal history during deposition. High-resolution FARO arm scanning was employed to quantify dimensional deviations of the cylindrical shell and stiffeners, while in-situ thermal data were recorded throughout fabrication to characterize localized thermal exposure. Preliminary results indicate that annealed specimens fabricated at higher print speeds exhibit greater dimensional deviation compared to their conventional printhead counterparts, likely due to excessive localized heat accumulation and insufficient cooling time. However, as the print speed was substantially reduced, the annealed specimens demonstrated improved geometrical fidelity and enhanced surface finish quality. These findings provide insight into the relationship between localized thermal exposure, deposition conditions, and dimensional stability, supporting the development of improved thermally assisted fabrication strategies for lightweight thin-walled stiffened FFF structures.
2:10 PM
Decoupling Additive Manufacturing Tolerance from Nondestructive Evaluation Ultrasonic Resolution Using 3D-Printed Lithophanes: Kenneth Shen1; Harshith Adepu1; Michael Sealy1; Luz Sotelo1; 1Purdue University
Ultrasonic testing is critical for evaluating sub-surface features, yet its effectiveness in additive manufacturing (AM) is often obscured by high printing tolerance errors. This study proposes a framework to isolate manufacturing noise from ultrasonic sensing performance using 3D-printed lithophanes of famous artworks as controlled geometric benchmarks. To quantify lithophane sample difficulty, a Brushstroke Complexity Index (BCI) is developed, utilizing a weighted average of stroke shape, skeleton curvature, and size variability. To decouple error sources, two Structural Similarity Index Measure (SSIM) metrics are calculated to establish a manufacturing error baseline and compare UT reconstructions to physical samples respectively. By analyzing the delta between these two metrics across a broad range of BCI values, the study successfully isolates the capability of UT to detect fine, sub-micron variations independently of printing errors. This methodology provides a definitive standard for characterizing the practical resolution limits of nondestructive evaluation on complex, non-ideal surface geometries.
2:30 PM
Resolving Enclosed Internal Structures in Laser Powder Bed Fusion: Grayson Briles1; Wisumitra Tirapanish1; Alina Meunier1; Harshith Adepu1; Partha Pandit1; Salil Bapat1; Luz Sotelo1; 1Purdue University
While Laser Powder Bed Fusion (LPBF) excels at fabricating complex geometries with high precision, issues with internal defects and geometries often arise. Past studies have assessed the effect of build orientation on circular geometries and open-ended channels. Still, less is known about the impact of enclosure and orientation on internal features. The objective of this study is to test whether the print orientation of LPBF parts impacts the ability to manufacture and resolve complex internal geometries. Two LPBF samples with hidden internal numbers were printed using different build orientations. Immersion ultrasound and X-ray CT data were collected to assess the fidelity of the internal geometry to the CAD models. Results show that features aligned with the build direction exhibited lower dimensional error, whereas curved features and downskin produced the highest inaccuracy. Overall, optimal orientation depends on aligning the critical internal features with the build direction to minimize the geometric error.
2:50 PM
Testing the Use of Various Minkowski Distances in Functional Grading of Multi-Material Additively Manufactured Origami-Based Mechanisms: Evelyn Thomas1; Jared Butler1; Nicholas Meisel1; 1Pennsylvania State University
Thick-folding origami-based mechanisms have been adapted for additive manufacturing, reducing part count and fabrication complexity. Within such mechanisms, rigid-foldable designs require high stiffness in panels and low stiffness in surrogate folds, motivating spatially varying material properties. Voxel-based design enables multi-dimensional functional grading based on distance fields; however, the choice of distance metric can significantly influence gradient formation and, consequently, mechanical performance. Minkowski distance is a generalized distance formula that reduces to create other types of distances such as Manhattan, Euclidean, and Chebyshev distance within multiple dimensions. Each of these distances has different impact on the resultant gradient and thus, the distribution of the material properties. This work expands upon the extant work to encompass higher-order dimensions of space and reveals the extent to which higher-order voxel-based design can reduce stress. This enables more complex mechanism design with refined gradients and lower possibility of interfacial failure at point-like interfaces.
3:10 PM Break
3:30 PM
Characterization and Design of Digital Composites via Multi-Material Inkjet 3D Printing for Soft Tissue Replication: Joseph Passarello1; Charles Wade1; Robert MacCurdy1; 1University of Colorado, Boulder
Multi-material inkjet 3D printing offers site-specific control over composition, enabling fabrication of high-fidelity tissue simulants with tunable mechanical behavior. This study presents a method for mapping clinically relevant tool-tissue interactions of soft biological tissues via 3D printed multi-material composites. Composites made from elastomeric, gel-like, and liquid base resins were fabricated and characterized through spherical indentation and needle insertion testing to quantify indentation-derived Young's moduli and needle insertion behavior. The printable material space was shown to overlap with the mechanical properties of fat, muscle, internal organs, and vascular tissues. We established predictive mappings between digital composite formulation and mechanical properties, enabling inverse composite design for indentation-driven Young's modulus and needle insertion slopes. Validation experiments confirmed that printed composites reproduced target tissue mechanical responses. By combining indentation and tool-tissue interaction metrics, this method enables scalable fabrication of mechanically realistic soft tissue simulants for medical training and procedural simulation.
3:50 PM
Comparative Analysis on Traditional Manufacturing and Additive Manufacturing on Aluminum Matrix Alloy: Emilio Ceniceros Ortega1; Johnathan Ornales1; Elva Andujo1; Sayuri Komiyama Perez1; Omar Banda1; Patricio Sebastian Rodriguez Beltran1; Joshua Caballero1; Jimena Coello1; Yuky Macias1; Brianna Herrera1; Rebecca Herrera1; Lizbeth Licerio1; Josue Lopez1; Cesar Lopez1; Maria Estrada Gonzalez1; Francisco Medina1; 1W.M. UTEP Keck Center
This research compares Laser Powder Bed Fusion (LPBF) additive manufacturing against traditional die-casting across four components: casing, heatsink, housing, and a load-bearing bracket, to guide industrial technology selection. A characterization workflow combining CMM, blue light scanning, X-ray CT, hardness mapping, tensile testing (ASTM E8), and optical microscopy was developed. Die-casting demonstrated superior dimensional accuracy, surface finish, and hardness (104–105 HV). However, LPBF produced significantly higher internal material quality, with near full density microstructures and far lower porosity, the die-cast heatsink contained 1,810 porosity instances versus only 47 in the LPBF equivalent. While die-cast parts achieved higher peak UTS in some samples, they exhibited brittle fracture behavior. LPBF parts showed superior ductility and consistent tensile performance (~250–260 MPa).Die-casting suits high-volume production prioritizing surface quality; LPBF is preferable where internal integrity, microstructural uniformity, and ductility are critical.
4:10 PM
Developing And Implementing Additively Manufactured Patterns For Sand Casting: John Hana1; Ajay Krishnamurthy1; Eric Johnson1; 1Eaton Research labs
This presentation shares a practical, experience‑driven view of deploying 3D printed patterns for sand casting in a production environment. The talk covers the evolution from early trials to foundry‑ready implementation, including pattern design considerations, material and printer selection, dimensional control, and surface finish strategies. Real‑world results are discussed, highlighting lead‑time reduction, tooling flexibility, and cost tradeoffs relative to conventional patternmaking. Common challenges such as pattern durability, qualification, foundry acceptance, and organizational adoption are addressed through lessons learned during iterative builds and production trials. The presentation focuses on where additive tooling delivers clear value today, where limitations remain, and how cross‑functional alignment enabled successful adoption in an industrial setting.
4:30 PM
A Compact Test Artifact for Evaluating Fracture-Relevant Material Behavior in Laser Powder Bed Fusion: Sina Nejati Eghteda1; Albert To1; 1University of Pittsburgh
Qualification of laser powder bed fusion (LPBF) builds typically requires destructive mechanical testing of separately fabricated specimens, adding significant cost and turnaround time to the manufacturing workflow. This work presents a compact test artifact that can be printed alongside LPBF production parts and evaluated on the build plate to provide indicators of fracture-relevant material behavior. The artifact geometry is designed so that controlled loading produces a measurable mechanical response sensitive to variations in material condition arising from different process parameters and defect populations. Artifacts fabricated under a range of LPBF conditions are evaluated, and the extracted response metrics are compared against results from standard fracture specimens to assess directional agreement. Preliminary findings indicate that the artifact response differentiates between process conditions associated with distinct defect characteristics. The approach offers a potential pathway toward faster, lower-cost assessment of build quality in LPBF production environments.
4:50 PM
Fabrication and Mechanical Characterization of Dissimilar Inconel 625/CuNi30 Interlocking Joints Using Laser Powder Directed Energy Deposition: Sina Nejati Eghteda1; Albert To1; 1University of Pittsburgh
Joining dissimilar metals presents persistent challenges due to differences in thermal expansion, melting points, and metallurgical compatibility. Interlocking joints fabricated via laser powder directed energy deposition (LP-DED) offer a pathway to mechanical load transfer across a bimaterial interface without relying primarily on metallurgical bonding. This work investigates the fabrication and mechanical characterization of dissimilar Inconel 625/CuNi30 interlocking joints produced by LP-DED. Digital image correlation (DIC) is employed during mechanical loading to map full-field strain distributions, identify regions of strain concentration, and track the sequence of failure initiation across the joint. The effects of deposition sequence—alternating the print order of each alloy—and interlocking overlap distance on joint stiffness, load capacity, and failure mode are systematically examined. This study aims to establish how deposition strategy and geometric parameters govern the mechanical response of LP-DED multi-material assemblies, with the goal of developing design guidelines for structural applications requiring combined thermal and mechanical performance.