Subsequent Mechanical Testing Research Articles

Hydrogen Embrittlement of Ferritic Steel 1.4104

Abstract The primary goal of this study was to investigate laboratory techniques for hydrogenating selected steels and to examine the hydrogen embrittlement of steel 1.4104. These processes, which involve hydrogenation and subsequent mechanical testing, are rarely performed in laboratories due to the need for precise, costly equipment and the inherent risks associated with hydrogen’s highly reactive and explosive nature. Various theories have been proposed to explain the mechanisms behind hydrogen embrittlement in steels. These theories attribute material degradation to hydrogen’s interaction with the steel microstructure. However, their applicability is often limited, as they are developed for specific conditions and may not fully describe the phenomenon under different scenarios. This work focused on hydrogenating steel 1.4104 using two distinct methods: immersion and cathodic. The aim was to induce embrittlement and compare the resulting fracture surfaces, particularly after conducting Charpy impact tests, to evaluate the effects of each hydrogenation method.

Reconstructing 3D histological structures using machine learning (artificial intelligence) algorithms.

Histomorphometry is currently the gold standard for bone microarchitectural examinations. This relies on two-dimensional (2D) sections to deduce the spatial properties of structures. Micromorphometric parameters are calculated from these sections based on the assumption of aplate-like 3D microarchitecture, resulting in the loss of 3D structure due to the destructive nature of classical histological processing. To overcome the limitation of histomorphometry and reconstruct the 3D architecture of bone core biopsy samples from 2D histological sections, bone core biopsy samples were decalcified and embedded in paraffin. Subsequently, 5 µm thick serial sections were stained with hematoxylin and eosin and scanned using a3DHISTECH PANNORAMIC 1000 Digital Slide Scanner (3DHISTECH, Budapest, Hungary). Amodified U‑Net architecture was trained to categorize tissues on the sections. LoFTR feature matching combined with affine transformations was employed to create the histologic reconstruction. Micromorphometric parameters were calculated using Bruker's CTAn software (v. 1.18.8.0, Bruker, Kontich, Belgium) for both histological and microCT datasets. Our method achieved an overall accuracy of 95.26% (95% confidence interval (CI): [94.15%, 96.37%]) with an F‑score of 0.9320 (95% CI: [0.9211, 0.9429]) averaged across all classes. Correlation coefficients between micromorphometric parameters measured on microCT imaging and histological reconstruction showed astrong linear relationship, with Spearman's ρ‑values of 0.777, 0.717, 0.705, 0.666, and 0.687 for bone volume/tissue volume (BV/TV), bone surface/TV, trabecular pattern factor, trabecular thickness, and trabecular separation, respectively. Bland-Altman and mountain plots indicated good agreement between the methods for BV/TV measurements. This method enables examination of tissue microarchitecture in 3D with an even higher resolution than microcomputed tomography (microCT), without losing information on cellularity. However, the limitation of this procedure is its destructive nature, which precludes subsequent mechanical testing of the sample or any further secondary measurements. Furthermore, the number of histological sections that can be created from asingle sample is limited.

Effects of Er:YAG laser debonding on changes in the properties of dental zirconia.

To investigate changes in the optical and mechanical properties of novel zirconia ceramics applied in dentistry after Er:YAG laser debonding and to evaluate the feasibility and value of reusing zirconia restorations debonded by an Er:YAG laser. Four types of zirconia ceramics were investigated: self-glazed zirconia (SGZ), 3Y-TZP, 4Y-PSZ and 5Y-PSZ. Forty rectangular (25 mm*8 mm*1.5 mm) specimens were fabricated for each zirconia type, and a total of 160 specimens were manufactured. The zirconia specimens were divided into four subgroups according to the applied Er:YAG laser debonding process: the control group, 4 W laser group, 5 W laser group, and 6 W laser group. For each subgroup, 10 specimens were subjected to color tests (color difference (△E) and transparency parameter (TP) tests) and subsequent mechanical tests (flexural strength (FS), elastic modulus (EM), Vickers hardness (VH) and surface roughness (Ra) tests). The △E, TP, FS, EM, VH and Ra values were measured and calculated. One random sample from each subgroup was observed by SEM. Statistical analyses were performed by one-way ANOVA followed by post hoc comparisons (α = 0.05). The △E and TP values after Er:YAG laser debonding were not significantly different among the subgroups (P > 0.05). However, the 6 W laser group had the highest △E and lowest TP. The ranges of changes in △E and TP were below the clinically detectable threshold (△E = 1.2, △TP = 1.33). In terms of the mechanical properties, there were no significant differences in the FS, EM, VH or Ra among the subgroups. No obvious microcracks were detected on the surfaces of the zirconia specimens during SEM. Er:YAG laser debonding does not obviously affect the optical or mechanical properties of novel zirconia ceramics in dentistry. Moreover, it is potentially feasible and valuable to reuse zirconia restorations after Er:YAG laser debonding.

Heat Treatment Optimization and Nitriding Effects on Mechanical Properties of 32CrMoV12-10 Steel

32CrMoV12-10 steel is widely utilized in industries where high strength and toughness are crucial. This alloy is commonly used in manufacturing components like gun barrels, gears, and bearings, which demand exceptional mechanical properties. These parts typically undergo heat treatments, including hardening and surface enhancement techniques such as nitriding, to extend their fatigue life significantly. It is crucial to identify optimal heat treatment conditions to achieve desired material performance. In this study, commercial 32CrMoV12-10 steel was selected to investigate the impact of heat treatment parameters (temperature, duration time, and quenching media) on its mechanical properties. To analyse the effect of these parameters, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and the Taguchi Method were employed, facilitating a systematic examination of the process stages and subsequent mechanical testing outcomes, including Charpy V-notch impact, hardness, and tensile strength assessments. An optimal heat treatment protocol was established based on these analyses, and the nitriding depth of the optimally treated sample was examined using a micro-Vickers hardness tester. For comparative analysis, another sample with closely related outcomes was also evaluated. Results indicated that the surface hardness of the optimally treated Sample 10 reached 870 HV, with a core hardness of 417 HV, compared to non-nitrided Sample 3, which showed a surface hardness of 860 HV and a core hardness of 415 HV. Despite the proximity in their values, Sample 10 exhibited slightly higher micro-Vickers hardness than Sample 3. However, while Sample 3 fails to meet the specified tensile stress and hardness criteria, Sample 10, produced through optimization, meets criteria, ranging from 970 to 1040 N/mm², underscoring the efficacy of the optimization process facilitated by TOPSIS. This optimization was notable for its minimal experimental requirements, proving effective in conserving time, energy, and resources while investigating the processed material.

Friction stir processing: A thermomechanical processing tool for high pressure die cast Al-alloys for vehicle light-weighting

This study uses friction stir processing (FSP) for thermomechanical processing of high-pressure die-casting (HPDC) to modify microstructure and improve mechanical properties. FSP is carried out on two different HPDC aluminum alloys: (a) general-purpose, high-iron, HPDC A380 alloy and (b) premium quality, low-iron HPDC Aural-5 alloy in thin wall, flat plate geometry. Subsequent mechanical testing shows ∼30 % and ∼65 % enhancement in yield strength and tensile ductility. In addition, FSP leads to ∼10 times improvement in fatigue life for A380 alloy and ∼70 % improvement in fracture toughness for Aural-5 alloy. These findings emphasize the capability of FSP to modify the microstructure of HPDC Al-alloys-based structural components so that they can demonstrate a good combination of strength, ductility, fracture toughness, and high fatigue properties for long-term durability and reliability.

Thermal, chemical and mechanical characterization of Azadirachta indica tree gum

This study focuses on the comprehensive thermal, chemical, and mechanical characterization of neem gum, a natural, colorless, tasteless polysaccharide obtained from Azadirachta indica tree’s trunk. The collection process of gum involves manual extraction from crude neem tree exudates, followed by thorough cleaning and homogenization with water. A portion of the resulting gum is then filtered, allowed to thicken, and naturally dried for subsequent mechanical testing. Various analytical techniques, such as thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to determine the thermal properties, Fourier transform infrared spectrometry (FTIR) to find the functional groups, scanning electron microscopy (SEM), and micro-X-ray fluorescence analysis (µ-XRF) to decide the elemental composition, microhardness, tensile, flexural, and compression tests to determine the mechanical properties, are employed in this study. The thermal and mechanical properties of neem gum have been relatively unexplored, and this highlights the novelty and importance of this research. The results are analyzed and compared with other natural tree gums. The pH of 5.07 shows that the gum is slightly acidic in nature, and the peaks obtained from thermal analysis demonstrate that it doesn’t have a melting point. The microhardness value, tensile strength, flexural strength, and compressive strength of neem gum are 238.64 MPa, 1.0155 MPa, 1.899 MPa, and 1.1023 MPa, respectively. This research provides valuable insights into the diverse characteristics and potential applications of neem gum in various fields. It is being used in the pharmaceutical industry. It can also be used as a cap for cutting tools, such as drill bits, after manufacturing, during transportation to protect their sharp edges from damage.

Enhancing mechanical performance in SLS-printed PA12-slate composites through amino-silane treatment of mineral waste

The SLS additive manufacturing industry enables the development of products for diverse applications with distinct properties due to its excellent surface finish and ability to create varied part geometries, but it consumes high-performance materials with high acquisition costs. An extensive quarrying of stone leads to the accumulation of mineral residues, posing environmental hazards by contaminating soil and water when disposed of in landfills. The primary objective of the study was to incorporate mineral waste into the SLS technique and investigate the influence of its addition, along with a silane-based chemical treatment, on the mechanical performance of polymer-mineral composites (PA12-slate). Additionally, the feasibility of producing a highly loaded printed prototype, employing 50 wt% of mineral waste, was examined. Samples of PA12, PA12 blended with 50 wt% slate waste, and slate waste treated with silane underwent fabrication via selective laser sintering (SLS) and subsequent mechanical characterization, including tensile, flexural, and compressive tests. Additionally, the samples underwent accelerated aging using a QUV weathering tester, followed by mechanical characterization. The geometric accuracy, stability, and processing feasibility of these formulations were evaluated through SLS-printed composite prototypes utilizing PA12_50Sla_Si. It was found that the addition of 50% of slate to the PA12 presented mechanical properties decreasing compared to the printed PA12 only. However, an increase was verified when using silane-induced mineral bonding. The incorporation of mineral agents and silane enhanced the resistance of PA12 to aging. However, after aging, both tensile and flexural strength decreased across all printed samples. Nonetheless, this study showcased the feasibility of producing complex PA12-slate waste specimens containing up to 50 wt% of mineral waste using the SLS printing technique. Therefore, SLS presents itself as a viable means of adding value to this mineral waste.

Interbody cage implantation in cadaveric model of the ram spine: biomechanical tests

To evaluate the mechanical properties of poly(L-lactide) cage prototypes on cadaveric models of the lumbar spine ram model. Prototypes of neck devices were developed on the Ender 2v2 3D printer («Shenzhen Creality 3D Technology Co., Ltd.», China). We analyzed mechanical properties of experimental cages. Single-level lumbar discectomy and fusion with poly(L-lactide) and poly-ε-caprolactone cage was performed on 4 cadaver models. Subsequent mechanical tests of vertebral segment were conducted on Instron 5965 electromechanical testing machine (Instron, A Division of Illinois Tool Works, Inc., USA). Static and cyclic tests revealed rigidity, adequate fixation and no migration of cages. Biocompatible biodegradable cages is a perspective direction in medicine. Considering high incidence of postoperative complications associated with migration and subsidence of non-resorbable cages, we can assume that biodegradable implants can become a competitive analogue for spinal fusion.

Characteristics of overlying strata and mechanisms of arch beam failure in shallowly buried thick bedrock coal seams: A case study in western China

AbstractThe Yangjiacun coal mine, located in western China, exhibits distinctive characteristics, such as its shallow depth, thick bedrock, thin loose layer, and unique roof strata breaking movement. In this research, a comprehensive analysis of previous exploration data, subsequent mechanical testing, key stratum theory, natural equilibrium arch theory, and simulation tests and numerical simulations has been conducted to investigate the failure behavior of the overlying rock strata in the Yangjiacun Coal Mine. Specifically, the load‐bearing capacity of the key stratum structure in the bedrock and the morphological properties of the arch‐beam structure have been thoroughly examined. A mechanical model of the roof rock arch‐beam structure has been established, and an analytical formula for the limit size and stability criterion of the arch‐beam structure has been derived. The mining‐induced rock arch‐beam structure plays a crucial role in transferring the load of the upper strata to the surrounding goaf, thereby preventing subsidence and deformation of the overlying strata. However, the arch‐beam structure periodically experiences instability during the advancement of the working face, gradually progressing towards the upper layer until the main key stratum is breached and the arch‐beam structure collapses. Based on the characteristics of weathered rock and the arch‐beam failure model in the Yangjiacun Coal Mine, quantitative backfilling mining methods have been proposed to either compensate for the mining void created by coal extraction or limit the size of exposed key strata through strip mining, ensuring the stability of the R6 key stratum. This study represents a significant contribution to understanding the intricate failure behavior of overlying rock strata in coal mines and provides a valuable framework for the responsible and efficient extraction of coal resources in similar environments.

Preservation of Mechanical and Morphological Properties of Porcine Cardiac Outflow Vessels after Decellularization and Wet Storage.

Widely used storage methods, including freezing or chemical modification, preserve the sterility of biological tissues but degrade the mechanical properties of materials used to make heart valve prostheses. Therefore, wet storage remains the most optimal option for biomaterials. Three biocidal solutions (an antibiotic mixture, an octanediol-phenoxyethanol complex solution, and a glycerol-ethanol mixture) were studied for the storage of native and decellularized porcine aorta and pulmonary trunk. Subsequent mechanical testing and microstructural analysis showed a slight increase in the tensile strength of native and decellularized aorta in the longitudinal direction. Pulmonary trunk elongation increased 1.3-1.6 times in the longitudinal direction after decellularization only. The microstructures of the tested specimens showed no differences before and after wet storage. Thus, two months of wet storage of native and decellularized porcine aorta and pulmonary trunks does not significantly affect the strength and elastic properties of the material. The wet storage protocol using alcohol solutions of glycerol or octanediol-phenoxyethanol mixture may be intended for further fabrication of extracellular matrix for tissue-engineered biological heart valve prostheses.

Orientation-dependent plasticity mechanisms control synergistic property improvement in dynamically deformed metals

We demonstrate the ability to synergistically enhance strength and toughness in metals by tailoring the dominant plasticity mechanisms from impact-induced heterogeneous nanostructures. Using a laser-induced projectile impact testing apparatus, we impact initially dislocation-free single crystal microcubes at high velocities to induce grain size and dislocation density gradients. These gradient nanostructures exhibit heterogeneous deformation under subsequent quasi-static loading leading to enhanced strength and toughness. Transmission Kikuchi diffraction (TKD) analyses show that the synergistic property improvement arises from the complimentary intragranular and intergranular plasticity mechanisms: the pronounced intragranular dislocation plasticity within coarse grained regions provides increased strain hardening and toughness while the nanograined regions with high dislocation densities provide high strength and supplemental toughness enhancement through cooperative grain rotation and grain boundary migration. These plasticity mechanisms are activated to different extents depending on the specific impact-induced nanostructures, which depend on the orientation of the single crystal upon impact. Controlled [100]-face, [110]-edge, and [111]-corner impact of single crystal microcubes, subsequent quasi-static mechanical testing, and pre- and post-compression nanostructural characterization provide a fundamental understanding of the comprehensive process-structure-property relations in heterogeneous nanostructured metals.

Study on Macromorphology and Microstructure of Laser Cladding NiCrBSi Alloy Cladding Layer

Laser cladding technology is an advanced surface modification technology that can achieve the coating, repair, and manufacturing of surfaces of metals, alloys, ceramics, and other materials. Laser cladding technology has the advantages of high efficiency, high accuracy, and the ability to achieve multi material composites, and is widely used in automotive, aerospace, shipbuilding, medical and other fields. However, there are also some problems with laser cladding technology, such as unstable weld pool morphology, uneven weld pool depth, and thermal stress, which limit its application range and the need to improve efficiency. Therefore, how to further improve the efficiency and quality of laser cladding technology has been an important research direction for researchers. Through nine orthogonal experiments without electromagnetic field, the effects of laser processing parameters, such as laser power, spot diameter, and scanning speed, on the quality of the cladding layer were studied. For melting height, scanning speed is the most significant influencing factor; For the melt width, the spot diameter is the most significant influencing factor; For the penetration depth, the laser power is the most significant factor. Through comprehensive comparison of subsequent morphology observation and mechanical property testing, it is concluded that laser power of 1500W, spot diameter of 3mm, and scanning speed of 4mm/s are the best process parameters, providing guidance for subsequent cladding experiments.

Mechanical and optical performance evaluations of embedded polyimide and PEEK coated distributed optical sensors in glass fibre reinforced composites with vinyl ester resin systems

Embedded optical fibre sensors (OFSs) offer the potential to monitor the internal strains at various stages during the manufacturing and service life of fibre-reinforced polymer (FRP) composite structures. Various aspects associated with the embedment of OFSs, such as integration, material compatibility, and sensing performance of the embedded sensor needs to be investigated to develop reliable OFSs based internal sensing platform for composite structures. In this study, Polyimide (PI) and Polyether ether ketone (PEEK) coated optical fibres (OF) were embedded into glass fibre-reinforced polymer (GFRP) composites to evaluate four important aspects associated with the embedment of OFs, which include; i). Structural integrity of the OFs against chemical reactions from vinyl ester resin and its additives through immersion testing, ii). Methods of integrating the OFs into layered glass fibres for the vacuum resin infusion manufacturing process, iii). Sensing performance of the embedded OFs during manufacturing and structural testing (tensile and compressive), and iv). Internal structural integrity of the embedded OFs and the host composite structure using X-Ray micro-computerised tomography technique (μ-CT). The results from the immersion testing and manufacturing process monitoring showed that both PEEK and PI coated OFs can resist the chemical and mechanical stresses caused by resin polymerisation during curing process. The subsequent mechanical testing showed a similar sensing performance by the PI and PEEK coated OFs. Under tensile loads, the OFs monitored the tensile strain distribution up to 7,000 με and compressive strain distribution up to −1,200 με under flexural loading without compromising their optical performance. Finally, the μ-CT scanning results had shown a minimal structural deterioration of the embedded OFs and host composite structure. The outcomes from this detailed experimental investigation on the embedment of OFS in GFRP structures provided useful information towards the integration and performance of optical sensors in composite structures.

Thin ply composite materials with embedded functional elements for cryogenic environments

• Use of thin plies in fiber reinforced composites to reduce microcracking due to thermal cycling. • Embedding of metallic functional elements into fiber composites. • Damage due to metallic elements embedded in fiber reinforced composites after thermal cycling. Fiber reinforced polymer composites are popular in aerospace applications due to stiffness-to-weight advantages for large structures. However, microcracking presents a limitation to the application of composites at cryogenic temperatures. Moreover, the effects of embedded functional elements are unclear at these temperatures. This study proposes thin-ply composites as a damage mitigation strategy for cryogenic environments. Thermal cycling and subsequent mechanical testing demonstrate the effectiveness of this strategy and provides guidelines for the integration of embedded elements.

Failure modes in dual layer thickness Laser Powder Bed Fusion components using a novel post-mortem reconstruction technique

To exploit the design freedoms of Powder Bed Fusion, parameters can be varied within sub-volumes of components to achieve the optimal part for both service conditions and manufacturing productivity. This involves prioritising mechanical strength in areas of structural significance and high volumetric build rates in areas of low structural significance. In theory, a component with similar mechanical behaviour to that seen in standard Laser Powder Bed Fusion parts can be built in significantly less time and at a reduced cost. In practice however, the boundary between such regions is yet to be understood and discretising components into sub-volumes can induce interfacial defects. In this study, an in-depth analysis of interfaces between disparate layer thickness volumes in single components has been explored, to gain information vital to solving interface quality issues so that LPBF design freedoms can be fully exploited. A novel 3D reconstruction technique has been demonstrated to characterise transient plastic behaviour of interfacial pores post-fracture. This technique enables post-mortem evaluation of additively manufactured parts and tracking of pore deformation during subsequent mechanical testing. X-ray Computed Tomography (XCT) identified interfacial pores up to 170 µm Feret diameter, with a voxel resolution of 6 µm. Micro tensile testing with in-situ microscopy exhibited a real-time mechanical response, observing evidence that these interfacial defects lead to fracture at interface locations. The 3D reconstruction technique found that pores constricted 10.0 – 14.1% in the x direction and 10.3 – 14.6% in the y direction after fracture – normal to the loading direction. These findings contribute towards improving Additively Manufactured biomedical implants and airframe components with reduced time and cost. • LPBF components are discretised into sub-volumes with different layer thicknesses. • XCT revealed pores are introduced at the interface between sub-regions. • Interface plane orientation has a great effect on interfacial porosity. • Micro tensile failure modes are observed at the interfaces with in-situ microscopy. • A novel 3D pore reconstruction technique is demonstrated.

Development of powder bed fusion – laser beam process for AISI 4140, 4340 and 8620 low-alloy steel

ABSTRACT This study focuses on process development and mechanical property evaluation of AISI 4140, 4340 and 8620 low-alloy steel produced by powder bed fusion – laser beam (PBF-LB). Process development found that increasing the build plate preheating temperature to 180°C improved processability, as it mitigated lack of fusion and cold cracking defects. Subsequent mechanical testing found that the low-alloy steels achieved a high ultimate tensile strength (4140:∼1400 MPa, 4340:∼1500 MPa, 8620:∼1100 MPa), impact toughness (4140:∼90–100 J, 4340:∼60–70 J, 8620:∼150–175 J) and elongation (4140:∼14%, 4340:∼14%, 8620:∼14–15%) that met or exceeded the ASTM standards. Mechanical testing also revealed limited directional anisotropy that was attributed to low levels of internal defects (< 0.1%), small grains with weak crystallographic texture and improved tempering due to build plate preheating and post PBF-LB stress relief. This indicates that with adequate process development, low-alloy steels produced by PBF-LB can meet or exceed the performance of conventionally produced alloys.

Prediction of properties on large diameter welded pipe: case study on 32″ × 16 mm X65 HSAW pipe

Large diameter welded pipes are amongst the most cost-effective transportation means for oil and gas. The production of those pipes involves different cold forming steps, as a result of which the mechanical properties on pipe will be different from the plate or coil properties. The steel manufacturer has several parameters at hand to control the properties of his final product. However, the pipe manufacturer only has a narrow process window, but eventually he is responsible for the properties of his product, i.e. the pipe. Furthermore, for some pipeline applications, the properties in both the transverse and longitudinal pipe direction must be within certain limits. This paper presents a Finite Element model which allows simulating pipe forming and subsequent mechanical testing and thus could be adopted to predict pipe properties from coil/plate properties. The complex hardening behaviour exhibited by pipeline grades is described by an extended version of the Levkovitch-Svendsen model, a constitutive model which accounts for isotropic, kinematic and distortional hardening. To validate the model, numerical predictions were compared to experimental results obtained from mechanical tests conducted on 32″ × 16 mm X65 HSAW (Helical Submerged Arc-Welding) pipes. The properties on pipe were evaluated by means of ring expansion tests and tensile tests on (flattened) full-thickness dog-bone samples and non-flattened round bar samples. Furthermore, tensile tests were performed in the transverse and longitudinal pipe direction and tests were conducted before and after hydrotesting. In general, the numerical predictions are in good agreement with the experimental data.

Discovery of surface biomarkers for cell mechanophenotype via an intracellular protein-based enrichment strategy.

Cellular mechanophenotype is often a defining characteristic of conditions like cancer malignancy/metastasis, cardiovascular disease, lung and liver fibrosis, and stem cell differentiation. However, acquiring living cells based on mechanophenotype is challenging for conventional cell sorters due to a lack of biomarkers. In this study, we demonstrate a workflow for surface protein discovery associated with cellular mechanophenotype. We sorted heterogeneous adipose-derived stem/stromal cells (ASCs) into groups with low vs. high lamin A/C, an intracellular protein linked to whole-cell mechanophenotype. Proteomic data of enriched groups identified surface protein candidates as potential biochemical proxies for ASC mechanophenotype. Select surface biomarkers were used for live-cell enrichment, with subsequent single-cell mechanical testing and lineage-specific differentiation. Ultimately, we identified CD44 to have a strong inverse correlation with whole-cell elastic modulus, with CD44lo cells exhibiting moduli three timesgreaterthan that of CD44hi cells. Functionally, these stiff and soft ASCs showed enhanced osteogenic and adipogenic differentiation potential, respectively. The described workflow can be replicated for any phenotype with a known correlated intracellular protein, allowing for the acquisition of live cells for further characterization, diagnostics, or therapeutics.

β-type TiNbSn Alloy Plates With Low Young Modulus Accelerates Osteosynthesis in Rabbit Tibiae.

β-type TiNbSn Alloy Plates With Low Young Modulus Accelerates Osteosynthesis in Rabbit Tibiae.

Mechanical and Microstructural Assessment of Inhomogeneities in Oxide Ceramic Matrix Composites Detected by Air-Coupled Ultrasound Inspection

Ceramic Matrix Composites (CMC) are promising materials for high-temperature applications where damage tolerant failure behavior is required. Non-destructive testing is essential for process development, monitoring, and quality assessment of CMC parts. Air-coupled ultrasound (ACU) is a fast and cost-efficient tool for non-destructive inspections of large components with respect to the detection of material inhomogeneities. Even though ACU inspection is usually used for visual inspection, the interpretation of C-scan images is often ambiguous with regard to critical defects and their impact on local material properties. This paper reports on a new approach to link the local acoustic damping of an oxide CMC plate obtained from ACU analysis with subsequent destructive mechanical testing and microstructural analyses. Local damping values of bending bars are extracted from ACU maps and compared with the results of subsequent resonant frequency damping analysis and 3-point bending tests. To support data interpretation, the homogeneous and inhomogeneous CMC areas detected in the ACU map are further analyzed by X-ray computed tomography and scanning electron microscopy. The results provide strong evidence that specific material properties such as Young’s modulus are not predictable from ACU damping maps. However, ACU shows a high, beneficial sensitivity for narrow but large area matrix cracks or delaminations, i.e., local damping is significantly correlated with specific properties such as shear moduli and bending strengths.