Mechanical and FEA-Assisted Characterization of 3D Printed Continuous Glass Fiber Reinforced Nylon Cellular Structures

The main objective of this study was to investigate the mechanical behavior of 3D printed fiberglass-reinforced nylon honeycomb structures. A Continuous Fiber Fabrication (CFF) 3D printer was used since it makes it possible to lay continuous strands of fibers inside the 3D printed geometries at selected locations across the width in order to optimize the bending behavior. Nylon and nylon/fiberglass honeycomb structures were tested under a three-point bending regime. The microstructure of the filaments and the 3D printed fractured surfaces following bending tests were examined with Scanning Electron Microscopy (SEM). The modulus of the materials was also evaluated using the nanoindentation technique. The behavior of the 3D printed structures was simulated with a Finite Element Model (FEM). The experimental and simulation results demonstrated that 3D printed continuous fiberglass reinforcement is possible to selectively adjust the bending strength of the honeycombs. When glass fibers are located near the top and bottom faces of honeycombs, the bending strength is maximized.

The acoustic property and impact behaviour of 3D printed structures filled with shear thickening fluids

In this study, the microstructures of the silica and styrene/acrylate particles and rheological behaviour of the three STFs were measured. The acoustic property and impact behaviour of 3D printed structures filled with STFs were investigated. The results showed that sound transmission loss (STL) of the structures filled with 46.5 vol% silica-based and 58.8 vol% styrene/acrylate-based STFs have been significantly improved, while their sound absorption coefficient (SAC) reduced greatly. The internal damage mechanism and energy absorption of honeycomb structures filled with different volume fraction STFs under low-velocity impact (LVI) loading were analysed, finding that the volume fractions and nanoparticles hardness of STFs has a significant influence on the impact resistance of the 3D printed honeycomb structures.

Anti-UBE2T antibody: a novel biomarker of progressive-fibrosing interstitial lung disease

Background Antifibrotic therapy has demonstrated efficacy against progressive-fibrosing interstitial lung disease (PF-ILD); therefore, it has become a priority to identify disease behavior before disease presentation. As autoimmunity is implicated in the pathogenesis of various ILDs, we explored the possibility of a circulating biomarker that can predict the chronic progressive behavior of ILDs. Methods A single-center retrospective cohort study was conducted to investigate a biomarker of PF-ILD. Circulating autoantibodies against 9,483 purified full-length human recombinant proteins of patients with interstitial pneumonia were screened by microarray analysis. The candidate auto-antibodies were verified their existence by multiples solution assay. In addition, enzyme-linked immunosorbent assay (ELISA) was performed in larger sample sets to evaluate accurate sensitivity, specificity and clinical significance in ILDs. Results In total, 61 healthy subjects and 87 patients with various ILDs enrolled in this study. Anti-UBE2T antibody was discovered by performing protein microarray and multiplex solution assay as a candidate biomarker of ILDs. By measuring its concentration by ELISA, anti-ubiquitin-conjugating enzyme E2T (UBE2T) antibody levels were significantly higher in patients with idiopathic interstitial pneumonias (IIPs), especially in those with PF-ILDs, than in healthy participants. The receiver operating characteristic analysis of anti-UBE2T antibody in diagnosing PF-ILD was calculated. The area under the curve was 0.85 and yielded a cut-off value of 238.1 ng/mL. Anti-UBE2T antibody-positive IIP patients demonstrated significantly higher ILD-gender age physiology scores, PF-ILD diagnosis rates and were more likely to develop honeycomb structures than anti-UBE2T-negative IIP patients after two years of follow up. The anti-UBE2T antibody positivity did not correlate with other commercial biomarkers such as KL-6 and commercial autoantibodies, suggesting the presence of anti-UBE2T antibody was independent of the others. Immunohistochemical staining of UBE2T in normal lungs was observed sparsely in the bronchiole epithelium and macrophages. Controversially, idiopathic pulmonary fibrosis lung tissue showed robust expression of the UBE2T protein in the lining epithelium of honeycomb structures. Conclusion This is the first report to describe anti-UBE2T antibody, a new biomarker that is significantly elevated in idiopathic PF-ILDs. This new antibody may constitute a sensitive biomarker to detect cases of PF-ILDs that are not currently detected by commercially available biomarkers.

Blast mitigation using polymeric 3D printed auxetic re-entrant honeycomb structures: A preliminary study

Protection of critical infrastructure in an urban environment is a challenging task, specifically against the vehicle bourne improvised explosive device threat. To design infrastructure to withstand this evolving threat, novel solutions and advanced materials need to be developed. One such material of interest are auxetics. This study experimentally analysed the mitigation of blast response of auxetic re-entrant honeycomb structures, with geometries varying between −ve 30° and +ve 30° using additive manufacturing (3D printing) techniques and non-explosive loading via shock tube. Re-entrant auxetic structures (−ve 15°) exhibited repeatable blast mitigation of 23% and reduced the transmitted pressure and impulse of the blast wave. Further highlighting their potential application as a protective measure to enhance a structures blast survivability.

Effect of loading rates on the in-plane compressive properties of additively manufactured ABS and PLA-based hexagonal honeycomb structures

Honeycomb structures find numerous applications in automotive, aerospace, sports, and other similar engineering fields. Such incorporation is made possible by the excellent crushing resistance and specific energy absorption capabilities. However, manufacturing such structures through conventional processes is highly laborious and expensive. Such a drawback can be largely mitigated by the adoption of additive manufacturing (AM) processes. Consequently, in this study, hexagonal honeycomb structures are subjected to experimental tests to determine their compressive strength under different loading rates. In addition to this, attempts have also been made to evaluate the effect of different materials and the unit cell dimensions on the compressive properties. The test specimens of different wall thicknesses are manufactured by fused deposition modelling (FDM) using PLA and ABS as the base materials. The samples are then subjected to compressive tests using a standard UTM to quantify the effect of the cell geometrical parameters and the loading rate on the overall compressive nature of the structures. The results show that the compression properties are primarily affected by the loading rate, material properties and the cell-wall thickness of the structures. The initial compressive yield stress and plateau stress generally increase up to a given value of loading rate, after which the strength decline. The cell-wall thickness of the structure influences the threshold loading rate. Therefore, this study provides a preliminary understanding of the compressive properties of AM hexagonal honeycomb structures to analyse the prospects for application in real-world engineering applications. It is proposed that such structures find profound applications in structural components of aerospace equipment, automotive parts, sports gear, and other similar areas of interest where high strength and energy absorption are of predominant importance.