Mechanical Behavior Of Materials Research Articles

Characterising the mechanical behaviour of dry-formed cellulose fibre materials

Abstract In the dry-forming process, paper pulp is formed without adding water, making it more resource-effective than traditional papermaking. It is a relatively new technology, patented only in recent years, and very few material investigations exist in the literature; hence, little is known of the constitutive behaviour. The stress state during forming is highly complex, including multiaxial loading, extreme densification, friction, large strains, and fibre-joint formation. This paper studies dry-formed materials at different compression levels, from the sparse mat to the highly densified network. Three primary loading modes are investigated: in-plane tension, out-of-plane shear and out-of-plane compression. The results indicate that the tensile modulus and strength scale quadratically and cubically to the density, respectively, while the shear properties start developing after the density passes a threshold value. The compressive properties proved difficult to quantify, mainly because of the discrepancy between the density before and after the compressive test. The dry-formed material was compared to wet-formed paper materials in the literature. This showed that the in-plane (tensile) properties and the out-of-plane shear strength are visibly lower while the shear stiffness is similar, compared to wet-formed materials. Nonetheless, the findings set a starting point for numerical simulations of the dry-forming process.

Composite electrospun membranes from cellulose nanocrystals, castor oil, and poly(ethylene terephthalate): Air permeability, thermal stability, and other relevant properties.

The study examined the use of cellulose nanocrystals (CNCs) in poly(ethylene terephthalate) (PET)/castor oil (CO) electrospun membranes, focusing on how CNCs influenced membrane properties for aerosol filtration applications. PET membranes were fabricated using 5 wt% and 10 wt% of CNCs and 2.5 wt% CO to assess its effectiveness as a compatibilizing agent, under a solution flow rate of 25.5 μL/min, a voltage of 25 kV, and a needle-collector distance of 8 cm. Nonaligned fiber membranes featured a network of ultrafine and nanofibers, while aligned fibers had an average diameter of over 300 nm (ultrafine fibers). The PET membranes permeability parameters were applied to Forchheimer's equation. All membranes presented values of Darcian (k1)/non-Darcian (k2) permeability coefficients in the order of 10-13 m2/10-8 m, respectively, near the range reported for commercial high-efficiency particulate air filters. CNCs acted as reinforcing agents, while CO was a compatibilizing agent, improving the material's mechanical behavior. Nonaligned PET/CO/10 wt% CNC presented a storage modulus (E') 2-fold higher/tensile strength 3-fold higher than pristine PET. Aligned PET/CO/5 wt% CNC, characterized in the preferential direction of fiber alignment, had approximately an E' 42-fold higher/tensile strength 6-fold higher than the same membrane, but tested in the perpendicular alignment direction. The glass transition temperature (Tg) values of PET (90-110 °C) did not exhibit any significant impact from membrane composition or fiber alignment. This study demonstrated the promising capability of PET-CNC bio-based electrospun membranes to be used in aerosol filtration or gas-solid and liquid-solid separations.

Tailoring Mechanical Performance in Bulk Nanoparticle-Structured ZnO and Al₂O₃: Insights from Deep Learning Potential Molecular Dynamics Simulations

The rapid advancements in nanotechnology have created unique opportunities to manipulate material properties at the nanoscale, particularly through the design of nanoparticle-structured (NP-structured) materials. Due to their distinctive mechanical and chemical properties, materials composed of nanoparticles, such as ZnO and Al₂O₃, are of high interest for applications in structural reinforcements, electronics, and catalysis. However, accurately predicting the mechanical behavior of NP-structured materials remains a challenge. This study investigates the mechanical properties of bulk nanoparticle-structured (NP-structured) materials composed of ZnO and Al₂O₃ nanoparticles in FCC and BCC configurations. We used deep learning potentials (DLPs) derived from density functional theory (DFT) calculations to comprehensively analyze stress-strain behavior, local shear strain distributions, and elastic properties across various nanoparticle sizes and compositions. Our findings reveal that nanoparticle size and crystalline arrangement are crucial in determining the mechanical performance of these materials. Smaller ZnO nanoparticles exhibit higher yield stress, ultimate stress, and Young's modulus in both FCC and BCC configurations, attributed to their higher surface-to-volume (S/V) ratio. In contrast, larger Al₂O₃ nanoparticles demonstrated superior mechanical properties, especially in FCC configurations, due to the strong ionic bonding and effective stress distribution inherent in Al₂O₃. In ZnO/Al₂O₃ composite systems, we found that the mechanical properties could be precisely tuned by adjusting the nanoparticle size and ratio. Larger nanoparticles in FCC arrangements contributed to higher yield stress and stiffness, while smaller nanoparticles in BCC arrangements provided better overall mechanical performance. This work highlights the potential of DLPs in accurately predicting and optimizing the mechanical properties of NP-structured materials, offering valuable insights for the design of advanced materials with tailored mechanical characteristics.

Mechanical constitutive behavior and microstructure evolution of high ductility concrete rapid repair material at different curing ages

Mechanical constitutive behavior and microstructure evolution of high ductility concrete rapid repair material at different curing ages

Full-Locked Coil Ropes with HDPE Sheath: Studies of Mechanical Behavior of HDPE Under Accelerated Aging.

In accordance with German guideline ZTV-ING Part 4, full-locked coil ropes are provided with a three-layer corrosion protection coating based on epoxy resin and polyurethane, which must be renewed regularly. An alternative method is to use a coating of high-density polyethylene (HDPE), which is extruded onto the rope. In this article, the mechanical behavior of the thermoplastic material is studied, taking into account various accelerated aging processes, which are derived from the climatic boundary conditions of a real bridge structure and implemented in tests. In addition to the quasi-static material behavior, which is described using the uniaxial tensile test, the cyclic conditioning, relaxation, type of production and oxidation stability are also investigated. Finally, the results obtained are evaluated with regard to the applicability of the material as corrosion protection for full-locked coil ropes.

MGT Photothermal Model Incorporating a Generalized Caputo Fractional Derivative with a Tempering Parameter: Application to an Unbounded Semiconductor Medium

This work introduces a novel approach to modeling the photothermal behavior of semiconducting materials by developing a Moore-Gibson-Thompson (MGT) fractional photothermal model that incorporates a generalized Caputo fractional derivative with a tempering parameter. This advanced model is specifically designed to analyze elastic plasmonic wave systems in photothermal environments, offering deeper insights into the interactions between thermal, mechanical, and electromagnetic fields in semiconductors. By including the two-parameter tempered-Caputo fractional derivative, the model accounts for memory effects inherent in the thermal and mechanical behavior of materials exposed to high-energy processes. The model is applied to an infinite semiconducting medium with a drag-free spherical cavity subjected to a dynamically changing thermal field. This setup is highly relevant to semiconductor technology applications, where precise control over thermal and mechanical responses is crucial. The findings of this study could have significant implications for the design and analysis of semiconductor devices, particularly those operating under extreme thermal or electromagnetic conditions.

Materials and structures at cold‐region and Arctic low temperatures: A state‐of‐the‐art review

AbstractConstruction of infrastructures in cold regions and the Arctic has grown rapidly since the 2000s, including railways, platforms, bridges, roads, and pipelines. However, the harsh low temperatures significantly influence the mechanical behaviors of construction materials, and bring safety and durability challenges to these engineering structures. This study made a state‐of‐the‐art review on materials and structures exposed to low temperatures. This review started from constructional‐material mechanical properties, including concrete, steel reinforcement, mild/high‐strength steel plate, and steel strand at low temperatures. It reflected that low temperatures improved the strength of construction materials. However, the freeze–thaw cycles (FTCs) had a detrimental effect on the modulus and strength of concrete. Furthermore, it was revealed that low temperatures increased the interfacial bonding strength between the steel reinforcements (or shear connectors) and concrete. Moreover, low temperatures improved the bending, shear, and compression resistances of reinforced concrete (RC) or prestressed concrete structures, but reduced the ductility of RC columns under lateral cyclic loads. Finally, reviews also found that low temperatures improved the compression resistance of concrete‐filled steel tubes using mild, high‐strength, and stainless steels, whereas FTCs and erosion reduced their compression capacity. In addition, low temperatures increased the bending resistance of steel–concrete composite structures, but the FTCs reduced it. The low temperatures bring challenges to the safety and resilience of engineering constructions, which requires careful further studies. Continuous further studies may focus on the durability of materials and the resilience of structures under diverse hazards, including earthquakes, impacts, and even blasts.

Mechanical Properties, Creep Characteristics, and Cracking Behavior of Rock-Like Materials with Parallel Double Joints of Different Thicknesses and Spacing

Mechanical Properties, Creep Characteristics, and Cracking Behavior of Rock-Like Materials with Parallel Double Joints of Different Thicknesses and Spacing

Investigation of the Flexural Behavior and Damage Mechanisms of Flax/Cork Sandwich Panels Manufactured by Liquid Thermoplastic Resin

This study investigates the flexural behavior of three sandwich panels composed of an agglomerated cork core and skins made up of cross-ply [0,90]2 flax or glass layers with areal densities of 100 and 300 g/m2. They are designated by SF100, SF300, and SG300, where S, F, and G stand for sandwich material, flax fiber, and glass fiber, respectively. The three sandwich materials were fabricated in a single step using vacuum infusion with the liquid thermoplastic resin Elium®. Specimens of these sandwich materials were subjected to three-point bending tests at five span lengths (80, 100, 150, 200, and 250 mm). Each specimen was equipped with two piezoelectric sensors to record acoustic activity during the bending, facilitating the identification of the main damage mechanisms leading to flexural failure. The acoustic signals were analyzed to first track the initiation and propagation of damage and, second, to correlate these signals with the mechanical behavior of the sandwich materials. The obtained results indicate that SF300 exhibits 60% and 49% higher flexural and shear stiffness, respectively, than SG300. Moreover, a comparison of the specific mechanical properties reveals that SF300 offers the best compromise in terms of the flexural properties. Moreover, the acoustic emission (AE) analysis allowed the identification of the main damage mechanisms, including matrix cracking, fiber failure, fiber/matrix, and core/skin debonding, as well as their chronology during the flexural tests. Three-dimensional micro-tomography reconstructions and scanning electron microscope (SEM) observations were performed to confirm the identified damage mechanisms. Finally, a correlation between these observations and the AE signals is proposed to classify the damage mechanisms according to their corresponding amplitude ranges.

Mechanical properties and fracture behavior of sandstone similar materials with different joint positions and thicknesses based on triaxial testing and PFC simulation

The mechanical properties and failure characteristics of joined rocks have an important impact on the disaster prevention of underground engineering and the sustainable development of mineral resources. The effects of confining pressure, joint location, and joint thickness on the mechanical properties of rock-like specimens under triaxial test have been studied. Furthermore, using the "DFN-age" function of PFC numerical simulation, the stress characteristics, and failure characteristics of rock specimens under different confining pressure, joint location and joint thickness are analyzed. The research results indicate that as the thickness of the joint increases and the joint position approaches the center of the specimen, the compressive strength of the specimen decreases. As the confining pressure increases, the compressive strength increases and failure modes of rock like specimens with different joint types also tend to be similar. The specimens manifest complex shear-tensile composite failures. In addition, the initiation cracks and main control cracks at the joint terminus can be classified as reverse tensile wing cracks, reverse shear cracks, shear cracks and tensile wing cracks. When the joint thickness of the specimen is 1.0 mm and the distance from the joint position to the center of the specimen is 10–20 mm, the crack evolution characteristics and stress distribution law of the specimen will undergo a transformation.

Fibreglass Reinforcement Influence on the Mechanical Behaviour of an ABS – PMMA – Fibreglass Composite Material

This study’s aim is to provide detailed information on how to control the mechanical behaviour of a short fibre unoriented composite material and adapt it for various applications. This study focusses on the challenging problem of recycling fibreglass waste mixed with thermoplastic polymers. The used method was thermoforming; preliminary studies have indicated this method as the most suitable for closing the loop in a manufacturing process – under the principles of a circular economy. Although this method is sustainable for this type of mixed waste, the research process is at an early stage and further studies and characterisations are required. From the data collected so far, this recycling method is the most efficient, both energetically and considering the added value of the final product. The results are encouraging and indicate a predictable behaviour of the studied reinforced composite material.

Optimization of carbon nanotubes in carbon black‐filled natural rubber: Constitutive modeling and verification using finite element analysis

AbstractCarbon nanotubes (CNTs) are novel one‐dimensional nanomaterials with a large aspect ratio and specific surface area, exhibiting excellent electrical and thermal properties that have led to their extensive utilization in rubber nanocomposites. In this paper, the effect of CNTs and carbon black juxtaposition on the properties of natural rubber is investigated using two different structures of CNTs, namely GC‐30 and GT‐210. The experimental results show that GT‐210 CNTs exhibit superior performance when incorporated into natural rubber. In addition, finite elements are employed for constitutive modeling to facilitate meaningful explorations in mechanical calculation and characterization of rubber filled with CNTs. Simulating the mechanical behavior of rubber materials under different working conditions (tensile and compressive) offers a cost‐effective and time‐efficient approach to predicting and optimizing material performance.Highlights Characterization of filler dispersion by Mooney–Rivlin curves. Fitting material stress–strain behavior using constitutive models. Offers an approach to predicting and optimizing material performance.

Microstructure and Mechanical Behavior of Structural Materials

Microstructure and Mechanical Behavior of Structural Materials

The Effect of Textile Structure Reinforcement on Polymer Composite Material Mechanical Behavior.

Investigating the impact of textile structure reinforcement on the mechanical characteristics of polymer composites produced by the compression molding technique was the goal of this work. An epoxy resin system served as the matrix, and various woven (plain, twill, basket), nonwoven (mat), and unidirectional (UD) textile structures made from E-glass fibers were employed as reinforcement elements. Compression molding of pre-impregnated textile materials (prepregs) was used to create the composites. The well-impregnated textile structures with resin into prepreg and the good interface between layers of the composites were verified during the manufacture of the polymer-textile composites using DSC thermal analysis and an SEM microscope. For the mechanical behavior, flexural properties were determined. The composite samples with unidirectional prepreg reinforcement have the highest longitudinal flexural strengths at roughly 900 MPa. The woven prepreg-based composite laminates show balanced flexural properties in both directions. Composites based on plane and basket prepregs have a flexural strength of about 450 MPa. Their flexural strength is over 20% lower than that of the samples made using twill prepreg. In both directions, nonwoven prepreg-reinforced composite samples show the least amount of resistance to bending stresses (flexural strength of roughly 150 MPa).

Mechanical and Wear Behavior of Aluminium Metal Matrix Composites Reinforced Ceramics Materials for Light Structures

Aluminium Alloy based Metal Matrix Composites (AAMMCs) has widely used in defense, aircraft and automobile applications because of their enhanced engineering properties with light weight metals. Nano sized silicon nitride (80 μm) is used as a reinforcement in this study, whereas aluminium alloy 8011 is selected as the matrix material. Using the stir casting method, metal matrix composites made of aluminium alloy 8011 with varying weight percentages of Si3N4 (0, 4, 8, 12, and 16) are created. The stir casted AL 8011/Si3N4 composites further heated under T6 condition. The AL 8011/Si3N4 – T6 composites are further subjected to Energy Dispersive X ray Analysis (EDAX) and Scanning Electron Microscope (SEM) to identify by the presence of elements and study the microstructure characterization, respectively. The density, microhardness and wear test are conducted by employing Archimedes principle, Vickers hardness tested and pin on disc equipment, respectively. The wear test is done at different sliding distances like (500, 1000, 1500 and 2000 m), applied load like (10, 20, 30 and 40 N) and kept sliding at a speed of 1 m/s. The increasing weight percentage of silicon nitride expands the increasing of density and Vickers hardness up to 12 wt % of silicon nitride and decreasing by 16 wt % addition. The wear resistances of AL 8011/12 wt % Si3N4 –T6 composite exhibits higher wear resistance than other Al8011 based composites.

Viscoelastic Models of Tissues. Mathematical Background and Hysteresis Loops

Abstract Human, animal, and plant tissues are typically viscoelastic, meaning their mechanical response lies between purely viscous and purely elastic behaviour. These tissues exhibit both viscous and elastic properties, modeled using viscoelastic frameworks. The mechanical behaviour of viscoelastic materials is determined by the relationship between stress σ and strain ε, referred to as the constitutive equation. In viscoelastic models, both stress and strain are functions of time. These models are often constructed using parallel or serial combinations of elementary components: Hookean elastic elements (H)and Newtonian viscous elements (N). The configurations formed through these combinations yield specific geometric equations which, when combined with physical equations, determine the corresponding global constitutive relations. This study presents an analysis and theoretical results related to an approximate viscoelastic model for aponeurosis, specifically represented by the Burgers model.

First-principles investigation of structural, mechanical, and electronic properties of AMgX3 (A=Ga, In, Tl, and X=Cl, Br, I) perovskites for optoelectronic applications

Abstract Metal-halide perovskites have emerged as a revolutionary material in solar energy technology, offering exceptional light-harvesting efficiency, eco-friendly characteristics, and low production costs. These materials are paving the way for next-generation photovoltaic devices with their outstanding optoelectronic properties and scalability for commercial applications. To determine the various features of the halide perovskites AMgX3 (where A stands for Ga, In, Tl, and X for Cl, Br, and I), we utilized DFT with the (Generalized Gradient Approximation) GGA-PBE (Perdew–Burke–Ernzerhof) exchange and correlation approximation to examine the structural, mechanical, electronic, and optical behaviors of the perovskite materials. Structurally, these materials exhibit cubic stability, vital for high-performance durability in photovoltaic devices. Mechanically, the calculated elastic constants verify their strength, suitable for environments where mechanical stability is critical, such as in aerospace electronics. The band gap range (1.22–3.69 eV) shows how versatile the materials are. TlMgI3 is suitable for infrared (IR) detection, whereas GaMgCl3 and InMgCl3 are optimal for ultraviolet (UV) applications. These findings support applications from IR sensors to UV photo detectors. The compounds’ optical properties, such as their high absorption coefficients, dielectric constants, and reflectivity, show how well they can collect and send light, which is important for solar cells and LEDs. The mechanical and optoelectronic properties collectively enhance their suitability for photonic and thermoelectric devices, offering scalable solutions for renewable energy and advanced photonics applications.

Exploring the Influence of Heterogeneity on Determination of a RVE for Concrete Structures

The mechanical behavior of a heterogeneous material is strongly influenced by the response of its constituents (and their respective interactions) at lower scales. This fact accounts for the nonlinearities observed at the macroscale, and consequently, the challenges in formulating constitutive models capable of providing accurate predictions in a practical application context. Essentially, there are two primary ways to represent a heterogeneous material, either through Phenomenological Models at a Single Scale or through Multiscale Models. Multiscale models represent the most robust approach to depicting a heterogeneous material. In these models, the connection between macro and meso levels is typically made through the concept of a Representative Volume Element (RVE). The RVE is the smallest sample of the material that can statistically represent the mechanical behavior of the material. Typically, in multiscale model applications, it is assumed that an RVE exists and that its size is initially prescribed. However, the appropriate determination of an RVE for quasi-brittle materials remains a subject of study. This paper discusses the determination of RVEs for concrete using normalized graded aggregate curves. For this purpose, numerical simulations were performed using the Finite Element Method, employing constitutive models based on Phase Field theory. Throughout the study, issues related to the size of the RVE and the determination of ergodic properties are discussed. The influence of the aggregate gradation curve on the mechanical behavior of the RVE and the influence of the aggregate-mortar interface are also examined. Finally, the difficulties encountered in determining the RVE in a practical application context are presented.

Shear strength reduction in triaxial compression of confined granular materials due to vibrations using the discrete element method

When subjected to external forces, the mechanical behavior of granular materials may range from static to dynamic. Unconfined granular beds, for example, are easily fluidized by vibratory loading. Under confinement, this type of material may also exhibit observable effects due to vibrations regarding their volumetric and strength behaviors. In this paper, the shear strength and dilatancy of dry confined granular materials subjected to vibrations are investigated using discrete element simulations of a triaxial cell. The material is first subjected to isotropic compression. Then, with controlled lateral stresses and imposed vertical motion, shear and compressive stresses are applied to a cubic sample. Additional harmonic displacements of the walls induce vertical and horizontal vibrations in the system during the shear tests. Finally, the impact of the amplitude, frequency, and direction of the vibrations on the angles of internal friction and dilatancy of the material is analyzed and compared to observations from the literature.

Unveiling the Influence of Natural Weathering on the Nanomechanical Properties of Magnetorheological Elastomers

Examining the physical aging of materials is essential for assessing their long-term performance and determining their suitability for specific applications. Material aging involves changes from their initial state, including deterioration or degradation. A key example of such a progressive, continuous process is the aging of materials in response to natural weathering conditions. While extensive research has focused on macro- and micro-scale aging, further investigation at the nanoscale could provide a more detailed understanding of material deterioration. This study explores the nanomechanical properties of magnetorheological elastomers (MREs) after nine months of natural weathering, focusing on stiffness, elasticity, surface roughness, and adhesion at the nanometer scale. Atomic Force Microscopy (AFM) with a sharp tip affixed to a cantilever was employed to characterize these properties. After nine months of exposure to natural weathering, MREs exhibited unique nanomechanical changes compared to their bulk properties, highlighting the significance of nanoscale analysis. At the nanoscale, the nanomechanical properties of MREs, including stiffness and elasticity, exhibited noticeable alterations within the first month of exposure, followed by a gradual reduction, and slight increments observed up to the nine-month mark. Surface roughness steadily increased over the nine months, while adhesion energy initially rose during the first month before gradually decreasing by the end of the study. These findings provide valuable insights into the material's mechanical behavior and offer a deeper understanding of its structural and functional properties at the nanoscale.