Specific Mechanical Properties Research Articles

Data driven performance prediction of titanium-based matrix composites

Titanium matrix composites (TMCs) offer superior specific mechanical properties compared to monolithic alloys. However, the complex interdependent effects of composition and processing on the resulting microstructure and properties make experimental determination of optimal TMC formulations challenging. This work explored a materials informatics approach integrating machine learning (ML) modeling with targeted fabrication and characterization for accelerated data-driven design of TMCs. A dataset of 368 data points on composition, processing method and mechanical properties of various TMCs was compiled from literature. Five ML regression algorithms were implemented to predict density, hardness and strength from composition-processing features. Among the models, random forest achieved highest accuracy with R2 scores above 0.93 and low errors. Fabrication of Ti-6Al-4 V/SiC using ML-guided parameters showed excellent agreement between predicted and experimentally measured properties. The ML models outperformed conventional empirical predictions by learning complex structure-property linkages from data. This integrated computational-experimental framework can guide rapid identification of property-optimized TMC formulations by reducing trial-and-error. Further work should focus on physics-based feature engineering and active learning. The data-driven approach demonstrated here shows promise for accelerating development of high-performance TMCs.

Biopolymers for Tissue Engineering: Crosslinking, Printing Techniques, and Applications.

Currently, tissue engineering has been dedicated to the development of 3D structures through bioprinting techniques that aim to obtain personalized, dynamic, and complex hydrogel 3D structures. Among the different materials used for the fabrication of such structures, proteins and polysaccharides are the main biological compounds (biopolymers) selected for the bioink formulation. These biomaterials obtained from natural sources are commonly compatible with tissues and cells (biocompatibility), friendly with biological digestion processes (biodegradability), and provide specific macromolecular structural and mechanical properties (biomimicry). However, the rheological behaviors of these natural-based bioinks constitute the main challenge of the cell-laden printing process (bioprinting). For this reason, bioprinting usually requires chemical modifications and/or inter-macromolecular crosslinking. In this sense, a comprehensive analysis describing these biopolymers (natural proteins and polysaccharides)-based bioinks, their modifications, and their stimuli-responsive nature is performed. This manuscript is organized into three sections: (1) tissue engineering application, (2) crosslinking, and (3) bioprinting techniques, analyzing the current challenges and strengths of biopolymers in bioprinting. In conclusion, all hydrogels try to resemble extracellular matrix properties for bioprinted structures while maintaining good printability and stability during the printing process.

Thermal decomposition and charring behavior of polyphenylene sulfide/para-amrid fiber composite paper with excellent fireproof property

A charring behavior was found during the combustion of para-aramid chopped fibers/polyphenylene sulfide (ACFs/PPS) composite paper, which formed a highly graphitized carbon layer structure with specific mechanical properties. This sturdy structure is composed of a dense carbon layer mixed evenly between the inner and outer layers, the outer layer can effectively block the spread of oxygen and degradation products, as well as external heat radiation, while safeguarding the inner layer's structural integrity. Herein, we systematically researched the flame retardancy and thermal degradation properties of ACFs/PPS composite paper. In combustion testing, the char of ACFs/PPS composite paper could support a weight of 50 g, while the neat aramid paper was burned through by fire, which indicates the Charcoal-forming property of ACFs/PPS composite paper is better than that of neat aramid paper, and ACFs/PPS composite paper has better fire resistance because of its good char formation. Meanwhile, we further showcase the application in electrically insulating and firefighting clothing interlayers.

Scalable Production of Robust and Tough Biomimetic Composite by Rapid In‐Situ Mineralization

AbstractNacre‐inspired materials with combined high strength and toughness have been widely developed and utilized for various engineering applications. However, existing preparation techniques suffer from intricate processes, high energy‐consumption, and lack of scalability, all of which collectively impede the efficient production of three‐dimensional materials. Here, a viable strategy is reported for the efficient and scalable production of bulk nacre‐mimetic materials, drawing inspiration from the intricate structures found in both nacre and wood. The prepared millimeter‐thick wooden artificial nacres (WANs) exhibit the presence of multi‐hierarchical lamellar structures, organic bridges, and micro‐asperities. Those features lead to the WANs exhibiting impressive mechanical performances, presenting excellent bending strength (≈93.31 MPa), toughness (≈7.40 MPa m1/2), tensile strength (≈122.59 MPa), and work of fracture (≈4.61 MJ m−3). In addition, owing to the low density (≈1.59 g cm−3), the WANs show much higher specific mechanical properties compared to nacre and related artificial nacre materials. Considering both its production process and exceptional properties, this material holds great promise for practical applications within the realm of engineering and structural fields.

Modular design of curved beam-based recyclable architected materials

Advances in manufacturing technologies have enabled architected materials with unprecedented properties. These materials are typically irreversibly designed and fabricated with characteristic geometries and specific mechanical properties, thus rendering them suitable for pre-specified requests. However, these materials cannot be recycled or reconstructed into different shapes and functionalities to economically adapt to various environments. Hence, we present a modular design strategy to create a category of recyclable architected materials comprising elastic initially curved beams and rigid cylindrical magnets. Based on numerical analyses and physical prototypes, we introduce an arc-serpentine curved beam (ASCB) and systematically investigate its mechanical properties. Subsequently, we develop two sets of hierarchical modules for the ASCB, thus expanding the constructable shape of architected materials from regular cuboids to complex curved surfaces. Furthermore, we demonstrate that the magnets attached to the centers of specific serpentine patterns of the modules allows the effective in-situ recycling of the designed materials, including sheet materials for non-damage storage, bulk materials for tunable stiffness, and protective package boxes for reshaping into decorative lampshades. We expect our approach to improve the flexibility of architected materials for multifunctional implementation in resource-limited scenarios.

Material aspects of wooden towers for offshore wind turbines

Possible new innovative materials for Counter Rotating Axis Floating Tilted Turbines are studied and discussed. The 40 MW version of the Counter Rotating Axis Floating Tilted Turbine (CRAFTT) will reach as far as 80 m below sea surface and up to 400 m above. The CRAFTT is an integrated design for floating offshore wind with two turbines on the same tilted shaft where the lower turbine is mounted directly on a rotating mast integrated with floater. The upper turbine will reach altitudes of 400 m. The system is designed to be a direct drive system, eliminating need for gearbox, taking advantage of the double air-gap speed of generator. With the generator placed at lower end as ballast the incentive to reduce weight for wings, tower and blades increase. Furthermore, wood is an attractive option as it enables both low CO2 impact production and higher degree of reusability. However, fatigue properties from both mechanical and thermal cycling needs to be addressed in order to evaluate new structural materials in the context of floating wind turbines. Starting from scratch without any preconceived notions, one could consider timber as a potential option for the tower. In such a preliminary and qualitative deliberation, one can consider that the use of wood as the main load-carrying material in large structures has been proven during the last decade by the development of new high-rise wooden buildings, with even higher buildings with timber as the main structural component expected in the future, The tall wooden buildings have been made possible since wood has the advantage of having high specific mechanical properties, i.e. high strength and stiffness with respect to density in the grain direction, in addition to being renewable. Another advantage is that wood is less sensitive to fatigue than many metallic materials, since its hierarchical microstructure prevents the propagation dominant cracks when loaded in the longitudinal direction. Design against fatigue is crucial in wind turbine structures given the inevitable cyclic loading. As all materials, wood certainly has its drawbacks, the foremost being its sensitivity to moisture, which is of obvious concern in off-shore applications. Moisture has a softening effect, resulting in creep, and moisture may trigger chemical or microbial degradation. The development of barrier coatings of aluminium has shown to be very efficient in e.g. high-voltage cables and food packaging, making them impermeable to moisture and air. Such techniques should be applicable also in wood constructions. This presentation highlights the main points specific for wood as a construction material in the design of wood towers for wind turbines in offshore locations, which need to be addressed in design.

Additive manufacturing error quantification on stability of composite sandwich plates with lattice-cores through machine learning technique

Architected lattice structures are designed to achieve specific mechanical properties while maintaining relative lightweight. Additive Manufacturing (AM) facilitates the fabrication of lattice structures with complex geometries. However, manufacturing imperfections, e.g., node dislocation, radius variation, and waviness, inevitably affect the performance of composite structures, of which the impact is significant yet difficult to quantify. Herein, a virtual model-assisted AM error quantification scheme is proposed to alleviate this challenge. The influence of geometric imperfections on the static buckling behaviour for sandwich lattice-core panels is investigated. A recently developed Extended Support Vector Regression (X-SVR) is utilized to alternatively bridge multiscale analyses. By integrating the sampling and virtual modelling methods, the effect of AM errors can be comprehensively quantified with statistical moments, probability density function (PDF), cumulative distribution function (CDF), etc. Furthermore, high computational efficiency, robustness, and other inherent features highlight the applicability of the proposed AM error quantification scheme in engineering.

Controlling mechanical properties and energy absorption in AlSi10Mg lattice structures through solution and aging heat treatments

The use of Selective Laser Melting (SLM) has gained popularity due to its ability to produce complex-shaped parts, which includes lightweight lattice structures that are appealing to a variety of industries. AlSi10Mg alloy is a favored choice for SLM due to its excellent specific properties. The utilization of AlSi10Mg in lattice structures further reduces their mass while enhancing specific mechanical properties. However, the inherent brittle deformation behavior of as-built AlSi10Mg restricts the energy absorption potential of lattice structures. This study explores the control of mechanical properties and energy absorption in AlSi10Mg lattice structures and bulk tensile samples through solution and aging heat treatments, examining their impact on microstructural transformations. The results show that solution heat treatment decreases the mechanical properties of lattice structures and bulk tensile samples while improving their ductility and energy absorption. This change is attributed to the transformation of the alloy's fine cellular microstructure into coarser Si-precipitates. Subsequent aging treatments lead to increased mechanical properties in lattice structures solution heat treated at 500 and 550 °C, albeit with a slight reduction in energy absorption. Intriguingly, lattice structures heat treated at 460 °C exhibit unchanged mechanical properties and energy absorption, as confirmed by the t-test. Additionally, the absence of the Al5FeSi intermetallic phase suggests that aging did not occur following solution heat treatment at 460 °C. These findings offer valuable insights into manipulating the mechanical properties and energy absorption of AlSi10Mg lattice structures through controlled heat treatments. Such control can significantly enhance the performance and functionality of lattice structures in practical applications.

Flexible Strain-Sensitive Sensors Assembled from Mussel-inspired Hydrogel with Tunable Mechanical Properties and Wide Temperature Tolerance in Multiple Application Scenarios.

Conductive hydrogels, exhibiting wide applications in electronic skins and soft wearable sensors, often require maturely regulating of the hydrogel mechanical properties to meet specific demands and work for a long-term or under extreme environment. However, in situ regulation of the mechanical properties of hydrogels is still a challenge, and regular conductive hydrogels will inevitably freeze at subzero temperature and easily dehydrate, which leads to a short service life. Herein, a novel adhesive hydrogel (PAA-Dopa-Zr4+) capable of strain sensing is proposed with antifreezing, nondrying, strong surface adhesion, and tunable mechanical properties. 3,4-Dihydroxyphenyl-l-alanine (l-Dopa)-grafted poly(acrylic acid) (PAA) and Zr4+ ion are introduced into the hydrogel, which broadly alters the mechanical properties via tuning the in situ aggregation state of polymer chains by ions based on the complexation effect. The catechol groups of l-Dopa and viscous glucose endow the hydrogel with high adhesiveness for skin and device interface (including humid and dry environments) and exhibit an outstanding temperature tolerance under extreme wide temperature spectrum (-35 to 65 °C) or long-lasting moisture retention (60 days). Furthermore, this PAA-Dopa-Zr4+ can be assembled as a flexible strain-sensitive sensor to detect human motions based on specific mechanical properties requirements. This work, enabling superior adhesive and temperature tolerance performance and broad mechanical tenability, presents a new paradigm for numerous applications to wearable sensing and personalized healthcare monitoring.

Effect of interface temperature on low‐velocity impact response of injection over‐molded short/continuous fiber reinforced polypropylene composites

AbstractInjection over‐molded short/continuous fiber reinforced composites are a unique class of materials for fabricating lightweight components having complex geometries in automotive manufacturing due to their higher specific mechanical properties, lower assembly cost, and short production cycle time. The influence of interface temperature on the low‐velocity impact response of short/continuous fiber‐reinforced polypropylene was experimentally investigated by varying the melt temperature. The over‐molded specimens fabricated at an interface temperature considerably higher than the melting point of polypropylene exhibited a 12% enhanced peak load with less impact damage compared with specimens over‐molded at a lower interface temperature. Optical analysis of impacted specimens over‐molded at lower interface temperature revealed interface debonding and insert delamination. Whereas insert delamination alone was observed for the specimens fabricated at higher interface temperature. The specimens over‐molded at high interface temperature exhibited less impact energy absorption and high compression strength after impact because of their strong interfacial adhesion.Highlights Impact energy absorption is less if melt temperature is high in injection over‐molding. Higher melt temperature enhances interface bonding by raising interface temperature. Interface debonding and insert delamination are the dominant impact failure modes. The compression strength after impact has increased with higher melt temperature. Impact and compression strength after impact is governed by the interfacial strength.

Ultra-high specific surface area spherical FePOx/SiO2 aerogel with excellent mechanical properties for the highly selective direct oxidation of CH4 to HCHO

Silica aerogels, characterized by their high porosity and substantial specific surface area, are suitable for applications as catalysts or catalyst supports. The simultaneous attainment of a substantial specific surface area and robust mechanical properties in aerogel materials remains a formidable challenge in material synthesis. Spherical FePOx/SiO2 aerogel materials were synthesized employing a combination of heating reflux, the sol-gel technique, and supercritical ethanol drying. These composites demonstrate an exceptional specific surface area, uniformly dispersed active components, shape controllability, and superior mechanical strength. A noteworthy enhancement in both specific surface area (1175 m2/g) and compressive modulus (7.56 MPa) surpasses many findings reported in extant literature. Under conditions of a reaction temperature at 650 °C and a flow rate of 97.5 mL/min, the HCHO selectivity and yield for 4 wt% FePOx/SiO2 aerogel were 18.3 and 4.2 times, respectively, higher than those of 4 wt% FePOx/SiO2 particles. These composites manifest significant selectivity towards the direct catalytic oxidation of CH4 to HCHO.

Influence of sintering temperature on the mechanical properties and biocompatibility of titanium-nano hydroxyapatite functionally graded materials

Titanium-hydroxyapatite functionally graded materials (Ti/HA FGMs) exhibit potential for specific mechanical and biological properties. Spark plasma sintering (SPS) has attracted considerable attention in recent years as a flexible process for manufacturing Ti/HA FGMs with accurate gradients of composition and microstructure. However, little information has been discovered about how the sintering temperature affects the mechanical behavior and biocompatibility of Ti/HA FGMs produced via SPS. In this study, the relationship between sintering temperature and the mechanical and biocompatibility properties of the Ti/HA FGM created by SPS is explored. 6-Layer functionally graded Titanium-Nano hydroxyapatite specimens were produced at three sintering temperatures of 850, 1000, and 1150 °C. To investigate the properties of the specimens, various techniques including compression test, Vickers hardness, X-ray diffraction (XRD), toxicity (MTT), and cell adhesion were performed. According to the results, TiO2 and TCP phases formed in the structure of FGM by raising the sintering temperature to 1150 °C, which decreased the compressive strength from 265 to 167 MPa and increased the maximum hardness from 419 to 894 HV. In addition, increasing the sintering temperature to 1150 °C enhanced the biocompatibility of the fabricated Ti/HA FGM. The optimum sintering temperature for generating Ti/HA FGM with appropriate mechanical and biocompatibility properties was 1000 °C.

Low-velocity impact performance of integrally-3D printed continuous carbon fibre composite sandwich panels

Sandwich panels are heavily used in industrial sectors where specific mechanical properties are of utmost importance due to their high weight-stiffness ratio and energy absorption capacity. Lightweight sandwich cores with bio-inspired topologies have been used as an advanced alternative to conventional bulk cores to improve performance. Nowadays, sandwich structures comprised of core and skins are typically manufactured with two different processes and are afterwards adhesively joined together. Here, with a less time-consuming and more efficient assembly procedure in mind, an integrally 3D-printing strategy is proposed. This investigation analyses the low-velocity impact and quasi-static perforation performance of sandwich core designs inspired by the beetle's forewing trabecular structure. It was found that the core material was responsible of the rate dependence observed in the force–displacement curves. More complex finite element models than those employed here are necessary to capture all the fracture modes observed experimentally.

An experimental study on ballistic limit: the effect of hole drilling on the mechanical properties of a polymeric composite plate produced by the resin transfer molding method

The high fracture strength and exceptional impact resistance of polymer-based composites are of paramount importance to various industries like aerospace, automotive, and construction. The resin transfer molding (RTM) process is used to produce composite samples of superior quality, minimal porosity, and reduced lamination defects. In the present study, the RTM method was employed to fabricate glass fiber-reinforced composites, aiming to investigate their specific mechanical properties and structural performance. The study initially determined the ballistic limit of the produced samples. Subsequently, experimental investigations were carried out to examine the impact of hole drilling on the tensile strength, flexural strength, and impact resistance of the samples. The results revealed that the produced polymer plate demonstrated a ballistic limit with a pressure of 11 bar and a speed of 104 m/s, leading to ball restriction in the plate. The sample without holes showed the highest fracture force, while samples with three and five holes exhibited reduced fracture forces. Additionally, bending force and impact resistance were lower in samples with multiple holes compared to the sample without holes. The impact resistance of the sample with five holes was the lowest among all configurations. The study revealed that the presence of three holes arranged in a row has a lesser impact on reducing the ultimate tensile force compared to the effect of five holes. Moreover, the bending test results indicated that sample failure occurred on the side under tension, resulting in higher bending forces than tensile forces.

Additive manufacturing of non-uniform scaffolds for mass center control

In addition to solid components, additive manufacturing can shape parts with internal structures or lattices to control specific mechanical properties such as the relation between strength and mass, inertia, and the center of mass. This study shows a strategy to produce scaffolds based on linear mapping, exponential parameterization, and Voronoi's diagram. The approach provides layer by layer, a net of lines denser on a specific layer point that can be defined to control the layer center of mass. This method is compatible with current CAD software and three-dimensional printing procedure stages; thus, it is easily reproducible. Furthermore, different linear mapping rulings and parameterizations were tested to evaluate the method's capabilities for modifying the center of mass of a symmetrical NACA 0015 profile. The numerical and experimental results show that it is possible to accommodate the center of mass between −8 and 18 mm to the NACA's theoretical center of mass.

Relationship between resistivity and physical properties of seafloor sediments in the hydrate production test area of the South China Sea

The vast distribution, abundant reserves, and high combustion utilization rate of natural gas hydrate make it an appealing alternative energy source. Nevertheless, the special physical and mechanical properties of the hydrate production test area in the South China Sea have led to frequent geological disasters, requiring monitoring and early warning of potential geohazards. To facilitate this process, a model was established to determine the relationship between sediment resistivity and physical properties in this area. However, there is currently no suitable sediment resistivity inversion model for this region. We obtained an 8 m-long core sediment sample from the hydrate production test area in the South China Sea using a core sediment sampler aboard the research vessel “Marine Geology 6”. Indoor geotechnical tests were conducted to determine the vertical variation characteristics of the sediment, and indoor resistivity tests were performed to obtain its resistivity vertical variation. Using empirical power function formulae, we established a relationship model between resistivity and physical properties, which we then compared with relevant data from nearby sea areas. This model lays the foundation for using in situ resistivity to invert the dynamic changes of sediment physical properties and promote the development of deep-sea engineering geology.

Development of bioinspired damage-tolerant calcium phosphate bulk materials

ABSTRACT Improving the damage tolerance and reliability of ceramic artificial bone materials, such as sintered bodies of hydroxyapatite (HAp), that remain in vivo for long periods of time is of utmost importance. However, the intrinsic brittleness and low damage tolerance of ceramics make this challenging. This paper reports the synthesis of highly damage tolerant calcium phosphate-based materials with a bioinspired design for novel artificial bones. The heat treatment of isophthalate ion-containing octacalcium phosphate compacts in a nitrogen atmosphere at 1000°C for 24 h produced an HAp/β-tricalcium phosphate/pyrolytic carbon composite with a brick-and-mortar structure (similar to that of the nacreous layer). This composite exhibited excellent damage tolerance, with no brittle fracture upon nailing, likely attributable to the specific mechanical properties derived from its unique microstructure. Its maximum bending stress, maximum bending strain, Young’s modulus, and Vickers hardness were 11.7 MPa, 2.8 × 10‒ 2, 5.3 GPa, and 11.7 kgf/mm2, respectively. The material exhibited a lower Young’s modulus and higher fracture strain than that of HAp-sintered bodies and sintered-body samples prepared from pure octacalcium phosphate compacts. Additionally, the apatite-forming ability of the obtained material was confirmed in vitro, using a simulated body fluid. The proposed bioinspired material design could enable the fabrication of highly damage tolerant artificial bones that remain in vivo for long durations of time.

In-situ nonlinear ultrasonic technique for monitoring damage in ultra-high performance fibre reinforced concrete (UHPFRC) during direct tensile test

This paper aims to employ the nonlinear ultrasonic technique for the in-situ monitoring of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) structures subject to tensile loads. The UHFPRC, characterized by specific mechanical properties of high compressive and tensile strength, provides the basis for this investigation. Particularly, the nonlinear parameter β of the nonlinear ultrasonic technique is extracted by formulating a theoretical model that accounts for the interaction of contacting rough surfaces under tensile loads. The experimental findings substantiate that β provides enhanced sensitivity and feasibility for evaluating crack conditions compared to the measurements obtained through conventional Linear Variable Differential Transformers (LVDT). Furthermore, this study explores the potential application of β to estimate tensile load condition by: i) establishing an estimation equation grounded in the relationship between tensile load and displacement (kN-mm); ii) incorporating β into this estimation equation to calculate the anticipated tensile load; and iii) comparing real and estimated tensile loads. The analysis outcomes reveal that estimated tensile loads are in good agreement with the actual loads. Although the estimation equation is based on the findings of this study, it underscores the potential applicability of β for estimating the load conditions in various structures.

Functionally graded IWP reinforced cementitious composites: Design, fabrication, and the enhanced ductility

The Schoen I-graph-wrapped package (IWP) structures have many promising applications for their high specific mechanical properties. In this work, functionally graded IWP (FG-IWP) architectures were developed and constructed to enhance the ductility of the produced cementitious composites. The FG-IWP architectures were designed using two grading strategies: relative-density-based and cell-size-based. The flexural test was used to investigate the mechanical behavior of the proposed composites, including flexural strength and deflections. The failure patterns and strain distributions of the specimens were measured using the Digital image correlation (DIC) approach. The results reveal that the designed IWP architectures noticeably improve the flexural strength and ductility of the composites. Comparing the FG-IWP to the uniformly configured IWP architectures, the grading strategies exhibit an increased ductility. Furthermore, the two grading strategies have different effects on ductility improvement. Cell size gradient strategy yields greater enhancement in flexural strength, whereas relative density strategy leads to better enhancement in ductility. The variations of cell size and relative density parameter ranges also result in distinct improvement on mechanical properties. Overall, the outcomes of this study present an FG-IWP-based novel approach for improving the ductility of cementitious materials.

Advanced Biomedical Applications of Multifunctional Natural and Synthetic Biomaterials

Biomaterials are mostly any natural and synthetic materials which are compatible from a biological point of view with the human body. Biomaterials are widely used to sustain, increase, reestablish or substitute the biological function of any injured tissue and organ from the human body. Additionally, biomaterials are uninterruptedly in contact with the human body, i.e., tissue, blood and biological fluids. For this reason, an essential feature of biomaterials is their biocompatibility. Consequently, this review summarizes the classification of different types of biomaterials based on their origin, as natural and synthetic ones. Moreover, the advanced applications in pharmaceutical and medical domains are highlighted based on the specific mechanical and physical properties of biomaterials, concerning their use. The high-priority challenges in the field of biomaterials are also discussed, especially those regarding the transfer and implementation of valuable scientific results in medical practice.