Mechanical Behavior Of Materials Research Articles

Investigation of the impact of fiber incorporation on the properties of high belite cement

In contrast to ordinary portland cement (PC), the manufacturing process of high belite cement (HBC) boasts superior resource utilization, reduced energy consumption, and diminished greenhouse gas emissions. Additionally, HBC exhibits notable strengths in terms of durability and mechanical properties. This study delves into the thermal characteristics of hydration, mechanical behaviour, and failure mechanisms of HBC materials, both with and without fiber admixtures, employing a multifaceted approach encompassing hydration heat experiments, uniaxial compression tests, Brazilian tensile tests, alongside advanced techniques such as acoustic emission (AE) and digital image correlation (DIC). The results indicate that HBC has lower hydration heat release, contributing to a reduction in hydration temperature rise, offering advantages in large-scale structural construction. In terms of strength development, HBC exhibits compressive and tensile strengths similar to PC, while the strength of basalt fiber-reinforced HBC is notably lower than both. In terms of failure modes, both HBC and PC undergo shear failure in uniaxial compression tests, whereas basalt fiber-reinforced HBC experiences splitting failure. In Brazilian tensile tests, HBC and PC exhibit single-direction cracking, while basalt fiber-reinforced HBC shows synchronous cracking at the top, middle, and bottom. Due to the crack-arresting effect of basalt fibers, basalt fiber-reinforced HBC displays a bimodal feature on the stress-strain curve and features a stress plateau on both the stress-strain and strain energy development curves.

A viscoelastic-viscoplastic thermo-mechanical model for polymers under hypervelocity impact

In hypervelocity impact (HVI) events, the thermo-mechanical behaviors of polymer materials are significantly influenced by viscous effects, thereby affecting energy absorption and shielding performance. A viscoelastic-viscoplastic thermo-mechanical model was newly developed to simulate the mechanical behavior and heat generation of polymer materials under HVI. The viscoelastic-viscoplastic constitutive equation and the Mie-Grüneisen equation of state (EOS) were applied to describe the deviatoric deformation and strongly nonlinear volumetric compression behavior. Moreover, the heat generation was calculated considering contributions from plastic work, irreversible entropy increase, and viscous dissipation which was not considered in the previous HVI numerical model. The temperature increase was calculated through adopting the apparent heat capacity method. The model was coded and seamlessly integrated into the LS-DYNA program through a user-defined material subroutine. Additionally, the FEM-SPH adaptive method was adopted to accurately simulate the fragmentation which always accompanies in the HVI event, wherein the finite element method (FEM) handles contact and deformation behavior, while the smoothed particle hydrodynamics (SPH) method addresses the formation and motion of debris clouds. Ultra-high molecular weight polyethylene (UHMWPE) was selected as the sample material, and its model parameters were calibrated based on the data from quasi-static and dynamic experiments. Good effectiveness and accuracy have been validated through comparing the simulation results and experimental results from the literatures. A noteworthy feature is that the model has the capability to capture the temperature distribution and various energy components induced by the impact, including viscous dissipation, plastic work, and residual energy. Finally, a comparison was made to explore the influence of viscosity on the impact response of UHMWPE plates. The analysis results indicate that material viscosity significantly improves energy absorption capabilities and overall shielding performance.

Modified Steinberg–Guinan elasticity model to describe softening–hardening dual anomaly in vanadium

Constitutive models are essential for describing the mechanical behavior of materials under high temperatures and pressures, among which the Steinberg–Guinan (SG) model is widely adopted. Recent work has discovered a peculiar dual anomaly of compression-induced softening and heating-induced hardening in the elasticity of compressed vanadium [Phys. Rev. B 104, 134102 (2021)], which is beyond the capability of the SG model to describe. In this work, a modified SG elasticity constitutive model is proposed to embody such an anomalous behavior. Elemental vanadium is considered as an example to demonstrate the effectiveness of this improved model in describing the dual anomalies of elasticity. This new SG elasticity model can also be applied to other materials that present an irregular variation in the mechanical elasticity and are important to faithfully model and simulate the mechanical response of materials under extreme conditions.

Experimental research on mechanical, material, and metallurgical properties of Inconel 600: Application in elevated temperature environment

Experimental research on mechanical, material, and metallurgical properties of Inconel 600: Application in elevated temperature environment

The strain gradient viscoelasticity full field solutions for Mode-I and Mode-II crack problems

The impacts of size and viscosity become distinctly evident when considering micro- and nano-scale phenomena for advanced materials with micro- and nanostructures. In this study, the mechanical behavior of the advanced material is characterized by using the strain gradient viscoelasticity theory, and a novel solution is presented for the mode-I and mode-II cracks, which is formulated based on the strain gradient viscoelasticity theory, employing the Wiener-Hopf method. Besides, the gradient-dependent viscoelastic crack solutions are directly derived by applying the correspondence principle that aligns strain gradient viscoelasticity with strain gradient elasticity within the Maxwell's standard linear solid model. Relative to the influence of elastic strain gradient effects, the involvement of viscous gradient effects instigates a reinforcement to the stress field around the crack tip, thereby offering a more reasonable representation of advanced materials crack behavior. When the viscosity effect is omitted or as time tends to infinity, the solutions based on strain gradient viscoelasticity theory converges to those on the classical strain gradient elasticity theory.

Physically consistent nonlocal macro–meso-scale damage model for quasi-brittle materials: A unified multiscale perspective

Despite great efforts in capturing the damage evolution law in multiscale approaches in damage mechanics, much less attention has been paid to the conversion from geometric damage to energy dissipation. In the present paper, the newly proposed nonlocal macro–meso-scale damage (NMMD) model is physically consolidated and a multiscale point of view is consistently adopted in both the damage evolution and energy dissipation. In this model, for each macroscopic material point a mesoscopic structure is attached such that all the point pairs composed of this point and the points in its influence domain are connected to it when the material is intact. The deformation field under loading will result in deformation of point pairs, and thus mesoscopic damage related to a point pair will occur if the deformation index of this point pair exceeds the prescribed threshold. Such mesoscopic change among point pairs connected to a material point within its influence domain has two-fold consequences: geometrically the accumulation of mesoscopic damage will result in macroscopic discontinuity, and simultaneously the free energy will be dissipated, leading to degradation of mechanical behavior of quasi-brittle materials. In other words, the damage as a metric of the geometric discontinuity will lead to the damage in the sense of energy dissipation and degradation of mechanical behavior for quasi-brittle materials, which can be physically captured by the ratio of summation of all the dissipated mesoscopic free energy in point pairs to the free energy of intact material within the influence domain. This energy-based macroscopic damage could then be inserted into the framework of continuum damage mechanics. Therefore, the conversion from geometric damage to energetic damage is implemented on the mesoscale instead of the macroscale, and thus a macroscopic energetic degradation function is not needed. In addition, the structured strain which is suitable for quasi-brittle materials can be adopted to determine the deformation index of point pairs. Correspondingly, the macroscopic free energy can be split into dissipative and non-dissipative parts. In this way, several inconsistencies in the previous NMMD models are remedied. The influence of mesoscopic model parameters is investigated in depth, and several numerical examples including mode-I, mixed-mode and compressive splitting fracture problems of quasi-brittle materials are carried out. Numerical results indicate that the proposed model can not only well capture the cracking process with or without initial cracks but also quantitatively predict the load–deformation curves without mesh size sensitivity. Moreover, due to the inherent physical consistency, in mixed-mode cracking problems the proposed model performs better than the previous NMMD model. Problems to be further studied are also discussed.

Ductile fracture prediction of additively manufactured Ti-6Al-4 V alloy based on void growth and coalescence of a unit-cell model

In this work, we have studied the fracture mechanism and proposed a micromechanical method with a unit cell model to predict the ductile fracture of additively manufactured (AMed) Ti-6Al-4 V alloy. The tensile experiments with smooth round bars and notched round bars were conducted to investigate the mechanical properties and ductile fracture behavior of materials. The proposed unit-cell model was validated by quasi-static tensile fracture tests to predict the ductile failure of titanium alloy manufactured by laser power bed fusion (L-PBF) under different stress states, which include a wide range of stress triaxialities. An equivalent initial void fraction was introduced to evaluate the ductile behavior of the titanium alloy. Our investigation shows that the stress states significantly influence the void coalescence behavior of AMed Ti-6Al-4 V alloy, and the fracture locus of L-PBF fabricated Ti-6Al-4 V alloy under different stress states was successfully predicted by the proposed unit-cell model under proportional loading. Our study provides useful guidance for the future design and application of metal materials for additive manufacturing.

Cementor: A toolbox to generate bio-cemented soils with specific microstructures

Bio-cemented soils can exhibit various types of microstructure depending on the relative position of the carbonate crystals with respect to the host granular skeleton. Different microstructures can have different effects on the mechanical and hydraulic responses of the material, hence it is important to develop the capacity to model these microstructures. The discrete element method (DEM) is a powerful numerical method for studying the mechanical behaviour of granular materials considering grain-scale features. This paper presents a toolbox that can be used to generate 3D DEM samples of bio-cemented soils with specific microstructures. It provides the flexibility of modelling bio-cemented soils with precipitates in the form of contact cementing, grain bridging and coating, and combinations of these distribution patterns. The algorithm is described in detail in this paper, and the impact of the precipitated carbonates on the soil microstructure is evaluated. The results indicate that carbonates precipitated in different distribution patterns affect the soil microstructure differently, suggesting the importance of modelling the microstructure of bio-cemented soils.

Thermo-mechanical finite element analysis of the solid-state metal deposition via lateral friction surfacing

Lateral friction surfacing (LFS) is a novel variation of the friction surfacing (FS) process for solid-state fabrication of ultra-thin and smooth metal coatings. In the LFS technique, pressing the lateral side of a rotating rod against the substrate's surface generates frictional heat and plastic deformation, leading to the deposition of consumable material from the lateral surface of the rod onto the substrate. This study presents numerical analysis for such a complex coupled thermo-mechanical process to investigate the distribution of various variables such as temperatures, local pressure, stress, and strain throughout the consumable rod and substrate. A finite element model of the process was developed through ABAQUS/Explicit method to investigate the thermo-mechanical response of rod and substrate materials by incorporating various features such as process parameters, mechanical behaviors of materials, temperature-dependent material properties, and failure criteria. The finite element model was validated by conducting experimental analysis using the same materials and values of process parameters. The finite element simulation results were consistent with previous experiments and affirmed that process temperature is lower than in conventional FS and localized in a small area, which can reduce thermal impacts on the consumable rod and substrate materials. Although the majority of the frictional heat was transferred to the Al6061-T6 rod due to its higher thermal conductivity, it was revealed that the maximum process temperature occurred on the mild steel substrate. The results of the study demonstrate that selecting an appropriate dwell-phase duration not only enhances the material's temperature to facilitate improved deposition but also ensures more consistent contact across all points along the rod's side, resulting in a uniform deposition.

The corrosion behavior of low carbon steel (AISI 1010) influenced by grain size through microstructural mechanical

Low-carbon steel (AISI 1010) is the predominant material used in industrial food processing equipment. Such equipment is vulnerable to the corrosive environment produced by various production stages. Different processes, such as sulphonation and carbonation, are used in the processing of sugar in the sugar industry, creating a corrosive atmosphere. The corrosion behavior of low carbon steel (AISI 1010) is strongly influenced by grain size variations, which in turn affect the microstructural mechanical properties of the material. The mechanical behavior and performance of metallic materials, including their corrosion resistance, is determined by grain size which is an important parameter for this phenomena. The impact of low-carbon steel (AISI 1010) microstructure on corrosion behavior is discussed in this work. Heat treatment produces two different types of microstructure from the same material, which are then analyzed. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) have both been used to study characteristics including morphology and content. By supplying an appropriate corrosive medium, the corrosion performance of several microstructures of low-carbon steel (AISI 1010) was assessed, and corrosion rates were calculated using weight-loss and electrochemical techniques. Results show that the creation of a protective coating with a higher charge transfer resistance is caused by the adsorption process. The variety in phases and grain sizes may contribute to the corrosion stability of different microstructures, and as a result, the corrosion rate lowers as average grain sizes are reduced. Employing the galvanic effect, pearlite increases the rate of ferrite corrosion. The study's findings support the notion that quenching low-carbon steel (AISI 1010) results in a finer grain structure and greater corrosion resistance.

Climatic Ageing of Low Density Polyethylene in Agricultural Greenhouses

Abstract Low-Density Polyethylene (LDPE) is a commonly employed plastic in the production of greenhouse covers due to its advantageous attributes of flexibility, durability, and transparency. Notably, LDPE’s ability to resist UV radiation plays a crucial role in protecting plants from harmful solar rays. However, the extended lifespan initially anticipated for this material is frequently undermined by the intricate process of LDPE aging. This study examines how the mechanical properties and creep behavior of monolayer and tri-layer PE materials change over nine months of natural aging in the Tiaret region of northwest of Algeria. Tri-layer polyethylene (PE) film outperforms mono-layer PE in strength (2.37x), elasticity (35%), and creep resistance due to its enhanced barrier against environmental factors. It maintains 50% elongation even after 9 months, while mono-layer PE degrades 50% in six months with a tensile strength of 14 MPa.

Numerical Analysis of Residual Stresses Effect in Multi-materials

Background: In this study, the effect of mechanical and physical properties of the metal and temperature is highlighted. The purpose of this study is to analyze the effect of these stresses on multi-materials. This work aimed to conduct a three-dimensional numerical study by the finite element method on the levels and distributions of the stresses in the Al2O3/NI/HAYNES multi-materials. These stresses of thermal and mechanical origin are generally detrimental to the service life of multi-material. Methods: The use of numerical resolution by finite element method is the most suitable for complex mechanical problems. It allows a more in-depth analysis of all points of the structure. In this study, a fundamental tool was constructed to resolve the mechanical behavior of materials subjected to complex solicitations. Therefore, the ABAQUS calculation code version 6.14 was used to analyze the residual stresses. Results: By interpreting the results in terms of stress variation, we identified the areas at risk; in particular, the nature of a joint effect plays a decisive role in the assembly of the right material in its mechanical resistance. This nature is defined in terms of stiffness (Young's modulus) and differential expansion (coefficient of thermal expansion). Conclusion: The presence of strong residual stresses can constitute a risk of damage to several materials. The difference between the coefficients of thermal expansion of the two materials (metal and ceramic) linked together induces, in these two constituents, normal internal stresses. This difference determines the level and distribution of these constraints. Moreover, the sign of this difference determines the state of the normal stresses.

Experimental and Numerical Investigation on the Mechanical Behavior of Rock-Like Material with Complex Discrete Joints

Experimental and Numerical Investigation on the Mechanical Behavior of Rock-Like Material with Complex Discrete Joints

Hydrogen-bond transformations of confined water and abnormal mechanical responses of hydrated AlPO4-11 framework under in situ high pressure

The behaviors of water under non-ambient conditions, especially in confinement environment, have long been of special interest due to the important roles in biological and geological processes. Here, we have performed an infrared spectroscopic investigation on the pressure-induced hydrogen-bond transformation of water in one-dimensional, elliptical channels of AlPO4-11. Upon compression, the hydrogen-bonds of confined water strengthen and water molecules transform from tetrahedral coordination configuration to low and intermediate configurations, which may be a high-density disordered state. This transformation is distinct from the commonly accepted liquid–solid and solid–solid phase transition in bulk water. Stronger hydrogen-bonds are formed and a further transformation of hydrogen-bonded water takes place in the hydrostatic environment of Ar than the case without pressure transmitting medium (PTM). In addition, the mechanical compressible behaviors and framework deformation of the host matrix are also discussed. X-ray diffraction study shows that the hydrated AlPO4-11 exhibits an unexpected high compressibility in Ar. Its bulk modulus before framework collapse is 14.1 GPa, 4 ∼ 5 times smaller than that in silicone. The anisotropic axial compressibilities of AlPO4-11 demonstrate that the ellipticity of the channel cross-section increases in silicone oil while it decreases in Ar because the relatively contractive behavior along minor axis direction is slowed down. Such pressure-induced responses are ascribed to the complex Ar-H2O-framework interaction after Ar penetration. This study offers us a new knowledge of crystal-fluid interaction in determining the mechanical behaviors of open-framework materials under high pressure and provides implications for the water evolution and circulation in water-carrying natural zeolites under extreme geological conditions in nature.

Influence of bioactive glass addition on the machinability, mechanical and biological response of Mg-PSZ-based biocomposites

The incorporation of bioactive glass (BG) into zirconia-based composite materials shows a feasible option to enhance the biological properties, reduce the sintering temperature, and resist the transformation of the tetragonal phase of zirconia. In this present work, the bioceramic composites, having the general formula [(100-x) (8 Mg-PSZ) – x (13–93 BG)] where x = 0 to 25 wt%, have been prepared and evaluated the effect of BG amounts on the machinability, mechanical and biological behavior of the composite material. The machining experiment is performed on an abrasive air jet machine (AAJM), and machinability is evaluated in the form of material removal rate (MRR), surface roughness (SR), and mechanics of material erosion (MME) at room temperature. The machinability results show that MRR decreases with enhancing the BG contents, and the SR follows the opposite trend of MRR. The MME indicates that the material is removed from the surface mainly due to the erosion crater and brittle fracture. Further, mechanical properties are evaluated, and it is found that the inclusion of BG frits and sintering temperature is substantially associated with the relative densities and the mechanical characteristics. Adding BG reinforcements increases the mechanical characteristics at lower sintering temperatures (1250 °C) while reducing the mechanical characteristics except hardness at higher sintering temperatures (1350 °C). Elastic modulus decreases with the addition of BG content up to 15 wt%; after that, it slightly increases up to 25 wt%. The in-vitro bioactivity and bio-degradation are tested in simulated body fluid (SBF), and both are increased by enhancing the BG contents up to 25 wt%. The in-vitro cell culture is performed on the MG-63 cell line. The biocompatibility increases with BG concentration (up to 25 wt%). Based on experimental results, it may be concluded that 8 Mg-PSZ/13-93BG bioceramic composites may be a potential choice for biomedical applications.

Tensile Tests for Material Characterisation of High- and Ultra-High-Strength Steels S690QL and S960QL under Natural Fire Conditions

The mechanical material behavior of mild steels is reversible in the cooling phase of natural fires, which is proven by experimental evidence. For the material behavior of high-strength steels during cooling, no results are yet available. The paper provides the first comprehensive test program on the constitutive material behavior of high-strength steels S690QL and S960QL as well as mild steel S355 J2 + N in the case of natural fires. It is elaborated that the mechanical material behavior of high-strength steels in the cooling phase differs from the behavior in the heating phase and is not reversible due to phase changes of the microstructure. A constitutive material model for structural fire design purposes is developed on the basis of experimental data and the soundness and reliability of the model are proven by a statistical study that systematically evaluates the deviation of the model prediction from the test data.

Investigation of mechanical behavior of sustainable construction materials: Recycled glass sand stabilized with natural binder material — Biopolymers

Presented in this paper is a study on the biopolymer treated recycled glass sand (BRGS). The effect of curing period, temperature, initial mixing moisture content and biopolymer concentration on mechanical behaviors of BRGS were examined through unconfined compaction strength (UCS), consolidated and drained triaxial test and scanning electron microscopy (SEM) analysis. The results revealed that biopolymer had a significant improvement on the soil stability. The mixing moisture content, biopolymer concentration and curing condition had a strong influence on soil strength. The strength of BRGS increased with dehydration, while further addition of biopolymer concentration may result in a decrease in strength. It was found that different types of biopolymers had their own preferences for curing conditions. The strength of agar treated RGS (thermal induced biopolymer) cured at 105 ℃ for 30 days was six times stronger than that cured at room temperature, while the optimal curing temperature of alginate treated RGS (ionic gelation biopolymer) was 50 ℃. The BRGS presented a slight decrease in friction angle but a significant increase in cohesion. The SEM image showing biopolymer uniformly wrapped RGS particles.

Mechanical behavior and microstructure evolution of different aluminum materials under shock loading

The mechanical behaviors and microstructure evolutions of different aluminum materials including high-purity aluminum, 7075 aluminum alloy and selective laser melted (SLM) AlSi10Mg alloy under shock loading were investigated through plate impact experiments and microstructure characterization. The results show that the Hugoniot elastic limit stress has nothing to do with impact velocity, but is related to material type; the peak shock stress significantly increases with increasing impact velocity and is somewhat affected by material type. The microstructure variation is highly dependent on the material type. In the 7075 aluminum alloy and selectively laser melted (SLM) AlSi10Mg alloy with relatively high strengths, the microstructure, including the grain size, grain shape and misorientation angle, is slightly influenced by the impact velocity. In high-purity aluminum with low strength, the microstructure is closely related to the impact velocity. As the impact velocity increases, dislocations, elongated subgrains, equiaxed subgrains and a fraction of low angle grain boundaries (LAGBs) first increase and then decrease, accompanied by the formation of numerous ultrafine equiaxed grains with sizes in the range of 1–5 μm. The limited adiabatic temperature rise during high-velocity impact cannot affect the microstructure. High rate loading was confirmed as an effective and promising method to refine grain structure for low strength materials.

Analysis of the mechanical, thermal and frictional behavior of Cu-sepiolite composite materials

To enhance the wear resistance of copper, sepiolite was used as a reinforcing element to explore the interface bonding strength between both. A comprehensive analysis was conducted from mechanical, thermal, and frictional perspectives to elucidate the role of sepiolite in copper. The results reveal that the interface between both remains undamaged under the applied loads of 0.4 N, with only minimal plastic deformation. However, excessive interface formation could compromise the continuity of the copper, resulting in reduced structural densification and impeded thermal conductivity. Moreover, sepiolite exhibited a particle strengthening effect, improving the mechanical strength. In which, H2 (20% sepiolite) exhibited the most significant characteristics, featuring a dense structure, small pores, and high shear strength and thermal conductivity, particularly excelling in Brinell Hardness (81.9HB). However, the frictional performance varied, gradually strengthening with the increasing amount of sepiolite. Notably, sepiolite acts as micro-protrusions to counteract friction forces. Partially fragmented sepiolite adheres to the friction surface, forming a mixed layer that facilitates the abundant generation of Cu2O. Besides, the CaCO3 in sepiolite undergoes thermal decomposition, resulting in the formation of CaO, both of which also function as micro-protrusions.

Withdrawal model for fiber motions in the tuft disentanglement

Tuft disentanglement involves the principal actions of opening and carding, which are essential processing in textile technology. In this article, tuft disentanglement is modeled as fiber withdrawal considering the fiber interactions within the tuft. Based on the reasonable tuft model, the kinematic constraints were constructed in the disentanglement considering the carding essence and fiber interactions. Combined with the dynamic equation, the state of the fibers can be solved as a linear complementarity problem due to the complementarity in the fiber interactions. The withdrawal forces verified the simulations, which capture the qualitative features of experiments. Also, the effect of the withdrawal parameters on disentanglement was studied. The simulation results showed that the withdrawal forces increased with increasing withdrawal velocities and decreasing gauge lengths. The simulation results are consistent with the experiments. The proposed computational framework can be extended for predicting the mechanical behaviors of other random fibrous materials involving fiber interactions.