Hybrid manufacturing approach for landing gear applications : WAAM Ti–6Al–4V on forged Ti–5Al–5Mo–5V–3Cr

High-strength metastable β-titanium alloys like Ti-5553 (Ti–5Al–5Mo–5V–3Cr) are frequently used in highly loaded aerospace components. Such aerospace parts tend to be expensive to traditionally manufacture due to current industry process limitations such as inflexibility for complex geometries, costs related to tooling for large forgings, extended lead times, poor machinability and high material waste. These challenges are leading to increased interest in exploring alternative manufacturing routes. This work investigates the use of additive manufacturing to deposit cost-effective and machinable Ti-64 (Ti–6Al–4V) alloy onto a forged Ti-5553 alloy substrate. The microstructure evolution, microhardness and tensile properties have been investigated for both the as-deposited as well as for stress relief heat-treated conditions. The results confirmed the formation of coarse columnar β grains with a fine basketweave α structure. The heat affected zones (HAZs) developed in the Ti-5553 substrate material from the cyclic thermal fluxes introduced from the melt-pool were characterized by a gradient microstructure of dissolving constituent phases with nearing proximity to the fusion zone. Tensile testing in the as-deposited condition was characterised with a UTS of 884 MPa and a ductility of 15%. Tensile samples extracted across the substrate-deposit interface all failed in the WAAM Ti-64 material and demonstrated comparatively greater strength but poorer ductility. A band of tensile residual stresses was imparted along the substrate, but was adequately stress relieved after heat-treatment at 600 °C. The heat-treatment led to the formation of more homogeneous α-phase laths throughout the HAZ of the Ti-5553 material and provided overall improvements to the strength and ductility

Amine functionalization of cholecyst-derived extracellular matrix with generation 1 PAMAM dendrimer

This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Biomacromolecules, copyright © American Chemical Society after peer review. To access the final edited and published work, see http://pubs.acs.org/doi/pdf/10.1021/bm701055k.A method to functionalize cholecyst-derived extracellular matrix (CEM) with free amine groups was established in an attempt to improve its potential for tethering of bioactive molecules. CEM was incorporated with Generation-1 polyamidoamine (G1 PAMAM) dendrimer by using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide and N-hydroxysuccinimide cross-linking system. The nature of incorporation of PAMAM dendrimer was evaluated using shrink temperature measurements, Fourier transform infrared (FTIR) assessment, ninhydrin assay, and swellability. The effects of PAMAM incorporation on mechanical and degradation properties of CEM were evaluated using a uniaxial mechanical test and collagenase degradation assay, respectively. Ninhydrin assay and FTIR assessment confirmed the presence of increasing free amine groups with increasing quantity of PAMAM in dendrimer-incorporated CEM (DENCEM) scaffolds. The amount of dendrimer used was found to be critical in controlling scaffold degradation, shrink temperature, and free amine content. Cell culture studies showed that fibroblasts seeded on DENCEM maintained their metabolic activity and ability to proliferate in vitro. In addition, fluorescence cell staining and scanning electron microscopy analysis of cell-seeded DENCEM showed preservation of normal fibroblast morphology and phenotype

In-process non-destructive evaluation of wire + arc additive manufacture components using ultrasound high-temperature dry-coupled roller-probe

In 2019, the global metal Additive Manufacturing (AM) market size was valued at € 2.02 billion and was predicted to grow by up to 27.9% annually until 2024. Additive Manufacturing plays a significant role in Industry 4.0, where the demand for smart factories capable of fabricating high-quality customized products cost-efficiently exists. Wire + Arc Additive Manufacturing (WAAM) is one such technique that WAAM utilizes industrial robotics and arc-based welding processes to produce components on a layer-by-layer basis. is enables automated, time and material-efficient production of high-value and geometrically complex metal parts. To strengthen the benefits, the demand for robotically deployed in-process Non-Destructive Evaluation (NDE) has risen, aiming to replace manually deployed inspection techniques deployed after the full part completion. The research presents a new synchronized multi-robot WAAM deposition & ultrasound NDE cell aiming to achieve defect detection in-process, enable possible in-process repair, and prevent costly scrappage or rework. Within the cell, the plasma-arc WAAM process, controlled by deposition software, is employed to build components. The full external control NDE approach is achieved by the real-time force/torque sensor-enabled adaptive kinematics control package. A high-temperature dry-coupled ultrasound roller-probe device is employed to assess the structural integrity of freshly deposited layers of WAAM components. The WAAM roller-probe is tailored to facilitate the in-process inspection by dry-coupling coupling with the hot (< 350 °C) non-flat surface of WAAM using a flexible outer silicone tyre and solid core delay-line at speed and at coupling high force[1-3]. The demonstration of the in-process inspection approach is performed on hot as-built titanium (Ti-6Al-4V) WAAM samples. The defect detection capabilities are assessed on artificial tungsten reflectors embedded in WAAM builds. In this work the defect detection is accomplished and analyzed using two separate approaches 1) layer-specific beamforming focusing imaging and 2) volumetric inspection using post-processing algorithms applied on collected Full Matric Capture data. The ultrasound in-process inspection using the dry-coupled roller-probe is driven by live Ultrasound Testing (UT) data acquisition, initiated within a minute from layer deposition completion. The collected UT B-scan frames are based on electronically focused beamforming through the roller-probe media into the depth of targeted layers. Subsequently, the results are presented on a plotted C-scan image, showing a top view over the interior of the targeted built volume. The results in this work are analyzed and compared to the X-ray computed tomography scan, conducted after the full-built completion and sample processing. The processed UT images show positionally accurate detection of embedded tungsten reflectors, with a minimum of 15 dB of signal-to-noise ratio. An accurate size estimation is also achieved for the tungsten defect extended along the sample’s length. The outcome of this research shows a successful defect detection and hence directly supports the industrial benefits of the WAAM process intending to achieve the automated production of first-time-right parts