This study investigates the impact of annealing time, temperature, and layer height on the tensile strength and dimensional change of three 3D printing materials (PLA, PETG, and carbon fiber-reinforced PETG). Samples with varying layer heights (0.1 mm, 0.2 mm, and 0.3 mm) were annealed at temperatures ranging from 60–100 °C for 30, 60, and 90 min. Tensile tests were conducted, and regression models were developed to analyze the effects of these parameters on tensile strength. The models exhibited high accuracy, with a maximum deviation of only 5% from measured validation values. The models showed that layer height has a significantly bigger influence on tensile strength than annealing time and temperature. Optimal combinations of parameters were identified for each material, with PLA performing best at 0.1 mm/60 min/90 °C and PETG and PETGCF achieving optimal tensile strength at 0.1 mm/90 min/60 °C. PETGCF demonstrated smallest dimensional change after annealing and had the best modulus of elasticity of all the materials. The study employed experimental testing and regression models to assess the results across multiple materials under consistent conditions, contributing valuable insights to the ongoing discussion on the influence of annealing in 3D-printed parts.

The modern approach to the recovery of damaged and missing bone tissue is increasingly focused on the application of implants capable of supporting the growth and recovery of parent tissue, rather than replacing the tissue itself. In this regard, the primary task of modern bone implants is to enable the targeted deformation of the implant against the expected load that that piece of bone should bear. The paper presents research related to anatomically shaped lattice scaffolds (ASLSs) made by the direct metal laser sintering (DMLS) of Ti-6Al-4V powder, and refers to the influence of the crossing angle between the outer lattice struts on the rigidity of the scaffold structure. The study includes the measurement of the deformation of two ASLSs designed for the same missing piece of rabbit tibia; these differed in terms of the crossing angle of the struts in the outer lattice and were exposed to quasi-uniaxial compression. The results show that the ASLS with outer struts that intersect at 60° (the angle between the compression direction and the strut axes is 30°) is more flexible compared to the ASLS with outer struts that intersect at 90° (the compression direction and the strut axes are colinear), even though its porosity is lower and volume is bigger.

This study investigates the elasticity of specific lattice structures made from titanium alloy (Ti6Al4V), namely, anatomically shaped lattice scaffolds (ASLS) aimed for reinforcement of the bone tissue graft that substitute a missing piece of the previously injured bone during its recovery. ASLSs that were used for testing were fabricated using the Electron Beam Melting (EBM) method. The mechanical properties of the ASLS were examined through uniaxial compression tests. Compression testing revealed the complex non-linear behavior of the scaffold structure’s elasticity, with distinct compression stages and deformation dependencies. The ASLS structures exhibited quasi-elastic deformation followed by the rupture of individual struts. Results demonstrate that the ASLSs can be stiffened by applying appropriate compression load and accordingly achieve the target elasticity of the structure for the specific load range. The modulus of elasticity was determined for different compression stages of ASLS, allowing interpolation of the functional relation between the modulus of elasticity and compressive force that is used for stiffening the ASLS. This study enhances the understanding of the mechanical behavior of the specific lattice structures made of Ti6Al4V and provides insights for the development of mechanically optimized anatomically shaped lattice scaffolds.

Proper fixation techniques are crucial in orthopedic surgery for the treatment of various medical conditions. Fractures of the distal humerus can occur due to either high-energy trauma with skin rupture or low-energy trauma in osteoporotic bone. The recommended surgical approach for treating these extra-articular distal humerus fractures involves performing an open reduction and internal fixation procedure using plate implants. This surgical intervention plays a crucial role in enhancing patient recovery and minimizing soft tissue complications. Dynamic Compression Plates (DCPs) and Locking Compression Plates (LCPs) are commonly used for bone fixation, with LCP extra-articular distal humerus plates being the preferred choice for extra-articular fractures. These fixation systems have anatomically shaped designs that provide angular stability to the bone. However, depending on the shape and position of the bone fracture, additional plate bending may be required during surgery. This can pose challenges such as increased surgery time and the risk of incorrect plate shaping. To enhance the accuracy of plate placement, the study introduces the Method of Anatomical Features (MAF) in conjunction with the Characteristic Product Features methodology (CPF). The utilization of the MAF enables the development of a parametric model for the contact surface between the plate and the humerus. This model is created using specialized Referential Geometrical Entities (RGEs), Constitutive Geometrical Entities (CGEs), and Regions of Interest (ROI) that are specific to the human humerus bone. By utilizing this anatomically tailored contact surface model, the standard plate model can be customized (bent) to precisely conform to the distinct shape of the patient’s humerus bone during the pre-operative planning phase. Alternatively, the newly designed model can be fabricated using a specific manufacturing technology. This approach aims to improve geometrical accuracy of plate fixation, thus optimizing surgical outcomes and patient recovery.

Computer-Assisted Surgery (CAS) involves applying various computer-based methodologies and devices to plan, guide, and perform surgical procedures, thereby improving outcomes throughout the surgical process. This study integrates the Characteristic Product Features (CPF) methodology with Method Of anatomical Features (MAF), both developed in-house to improve CAS. It enables the creation of the human organs’ geometrical models by including different relations between Regions of Interest (RGIs) models and specific properties, like functional, materials, and topological. Enhancing existing methodologies in CAS aims to offer a more comprehensive geometrical description of human organs, leading to the development of more precise and anatomically accurate personalized geometrical models. Creating customized geometry with accurately defined features is expected to enable surgeons to prepare and execute surgical interventions better, consequently improving patient care and recovery. The demonstration of successful geometry adaptation is shown by prototyping developed models using 3D FDM printing.

The quest for optimizing 3D printing processes to meet industrial demands for improved mechanical properties and dimensional stability is an ongoing challenge. This study delves into the task of determining the optimal 3D printing parameter (material and layer height) and annealing parameter (annealing time and annealing temperature) combinations for FDM 3D-printed parts through a systematic and objective approach. By utilizing Multi-Criteria Decision-Making (MCDM) methods, specifically the Analytic Hierarchy Process (AHP) for criteria weighting and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) for ranking, the study endeavors to address this challenge effectively. The primary aim of this research is to identify the most suitable 3D printing and annealing parameter combination that maximizes tensile strength and Young's modulus of elasticity while minimizing change in width, change in thickness, and change in length of the specimen after annealing. To achieve this, a comprehensive dataset stemming from the experimental analysis of three distinct materials (Polylactic acid - PLA, Polyethylene terephthalate glycol - PETG, carbon fiber reinforced PETG - PETGCF), three layer heights (0.1 mm, 0.2 mm, 0.3 mm), five annealing temperatures (60°C, 70°C, 80°C, 90°C, 100°C), and three annealing times (30 minutes, 60 minutes, 90 minutes) is employed. These criteria were determined based on the requirements of a specific industrial case study, highlighting their relevance and significance in real-world applications. The results show that the best combinations are the ones from PETGCF material with 0,1 mm layer height, with long annealing times (90 minutes) and low to mid annealing temperatures (60 - 70°C). The worst alternatives are the ones annealed at high temperatures (90 - 100°C), and with PETG material, as the dimensional change of this material are significant at high temperatures.