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This paper summarizes the results of one of the first comprehensive laboratory studies that was conducted to evaluate the effects of adding different contents of recycled polyethylene terephthalate (rPETE) as a modifier to an asphalt binder on the rheological and mechanical properties of the modified binder as well as on the agglomeration behavior between the rPETE and asphalt binder at a multiscale level. The high-temperature and low-temperature performances of the modified binder were investigated at the macro-scale and compared with those of the unmodified binder using dynamic shear rheometer (DSR) and bending-beam rheometer (BBR) rheological tests, as well as asphalt binder cracking device (ABCD) testing. The nano-scale evaluation of the binder properties, including the surface roughness, bonding energy, and reduced modulus, was accomplished using atomic force microscopy (AFM). The results indicated that the addition of rPETE enhanced the high- and intermediate-temperature rheological properties of the modified PG 64-22 binder. The low-temperature rheological properties and resistance to cracking decreased slightly with increasing rPETE content in the asphalt binder. However, this reduction was not remarkable when adding 4%, 8%, and 10% rPETE contents. The asphalt binder modified with 4% rPETE had a low-temperature grade of −22, similar to that of the unmodified binder, indicating that 4% rPETE can be added to the binder to improve its high- and intermediate-temperature properties without reducing its resistance to low-temperature damage. The AFM tapping-mode results indicated that the inclusion of rPETE in the asphalt binder improved the stiffness properties of the modified binder as compared with those of the control asphalt binder. In addition, the rPETE-modified binders showed rougher surfaces than the control binder. The addition of rPETE to the binder increased the values of the reduced modulus and bonding energy compared with those of the control binder. [ABSTRACT FROM AUTHOR]

In an Euclidean space, we study condensers with variable potential levels and the presence of a free part at the boundary. The asymptotic formula for the modulus of such condenser is obtained when the plates shrink to points. The generalized reduced modulus is defined as the second term of this asymptotics. We establish a relation between the reduced modulus and the discrete energy of the Robin function, and investigate its monotonicity and behavior under polarization. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of one of the first comprehensive laboratory studies that was conducted to evaluate the effects of adding different contents of recycled polyethylene terephthalate (rPETE) as a modifier to an asphalt binder on the rheological and mechanical properties of the modified binder as well as on the agglomeration behavior between the rPETE and asphalt binder at a multiscale level. The high-temperature and low-temperature performances of the modified binder were investigated at the macro-scale and compared with those of the unmodified binder using dynamic shear rheometer (DSR) and bending-beam rheometer (BBR) rheological tests, as well as asphalt binder cracking device (ABCD) testing. The nano-scale evaluation of the binder properties, including the surface roughness, bonding energy, and reduced modulus, was accomplished using atomic force microscopy (AFM). The results indicated that the addition of rPETE enhanced the high- and intermediate-temperature rheological properties of the modified PG 64-22 binder. The low-temperature rheological properties and resistance to cracking decreased slightly with increasing rPETE content in the asphalt binder. However, this reduction was not remarkable when adding 4%, 8%, and 10% rPETE contents. The asphalt binder modified with 4% rPETE had a low-temperature grade of −22, similar to that of the unmodified binder, indicating that 4% rPETE can be added to the binder to improve its high- and intermediate-temperature properties without reducing its resistance to low-temperature damage. The AFM tapping-mode results indicated that the inclusion of rPETE in the asphalt binder improved the stiffness properties of the modified binder as compared with those of the control asphalt binder. In addition, the rPETE-modified binders showed rougher surfaces than the control binder. The addition of rPETE to the binder increased the values of the reduced modulus and bonding energy compared with those of the control binder.

In this study, elastic modulus and hardness of fused silica were evaluated and then simulated by molecular dynamics (MD) and finite element analysis (FEA). The reduced modulus, hardness of the surfaces, and elastic modulus caused by the process along the depth of the indentation on the surfaces are evaluated by the nanoindentation method on the fused silica. The obtained results indicate that applying different indenters such as Berkovich and Cube-Corner reduces the amount and size of surface microcracks. The load-displacement of various indenters such as Berkovich and Cube-Corner with similar load at about 50 mN for the Berkovich shows a 400 nm displacement and a 1600 nm for the Cube-Corner indenter. In this study, the MD was used to describe the mechanical behavior of fused silica structures with atomic nanostructure as simulated at T 0 = 300 K and P 0 = 1 bar as the initial condition. The mechanical constants such as hardness (with Berkovich tip), elastic modulus (with Berkovich tip), and fracture toughness (with Cube Corner tip) of fused silica nanostructure can be calculated from this MD simulation in which the hardness of the atomic matrix is obtained at 8.84 GPa. [ABSTRACT FROM AUTHOR]

Scaling behavior relating the synthesis conditions with swelling degree, preparation concentration and crosslinking density of multifunctional ternary‐gels consisting of 2‐(dimethylamino)ethyl methacrylate (DMAEMA), hydroxypropyl methacrylate (HPMA) and glycidyl methacrylate (GMA) is reported. Swelling is controlled by DMAEMA portion of terpolymers and DMAEMA‐rich gels tended to swell more than GMA‐rich gels and increase in GMA increase polymer‐solvent interaction parameter, χ Critical conditions required for terpolymers to show phase transition are calculated as χ1=0.4993 and χ2=0.2959. Dependence of swelling degree ϕVon gel preparation concentration ν20$\nu _2^0$ as a function of solvent quality is examined. Good solvent prediction of φV≈(N¯Cν20)0.29${\varphi _V} \approx {({{{\overline N }_C}\nu _2^0})^{0.29}}$ indicates a crossover between entanglement‐dominated case and strongly cross‐linked case corresponding to low and moderate degrees of swelling. Swelling of ternary‐gels in different solvents shows that cyclohexanol is a good solvent and solubility parameter is 23.7 (MPa)1/2. Addition of hydrophobic GMA leads to a significant increase in stiffness of terpolymer gels. Increase in elastic modulus as‐prepared state is not monotonic and can be controlled by adjusting DMAEMA/GMA ratio since tertiary amine groups triggers cascading epoxy ring‐opening reaction. Reduced modulus Gr decreased with increasing swelling degree and scaling relation between modulus and swelling is found as Gr ≈ (ϕV)−0.66 which indicates that ternary‐hydrogels, limited to weak stretching regime, obey Gaussian statistics. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the microleveled rejuvenating effects of different rejuvenating agents on aged asphalt binders. In this study, an original asphalt binder (Shuanglong) with a grade of Pen70 was aged through an accelerated aging process specified by a strategic highway research program (SHRP). Two types of rejuvenating agents (one virgin asphalt binder and another petroleum product named HNCCY-1) were used to rejuvenate the aged asphalt binder at different concentrations. An atomic force microscopy (AFM) was used to study the microleveled properties of the rejuvenated aged asphalt binders, whereas the dynamic shear rheometer (DSR) was for rheological properties. The results showed that: (1) the number of bee structures increased, but their size decreased in the topographies of height or adhesion of the rejuvenated asphalt binders as the concentration of both the rejuvenating agents increased; (2) the roughness indexes gradually decreased and approached those of the original asphalt binder; (3) the diameter and threshold height decreased; and (4) the Young's modulus and reduced modulus became smaller. [ABSTRACT FROM AUTHOR]

In this paper, a dimensionless creep correction factor is proposed to simplify the calculation by using a fitting function of creep displacement combined with reduced modulus formula. Using experimental results of PA12 under different testing conditions during indentation, the creep‐corrected calculations of contact depth, reduced modulus, and hardness are studied. Results show that the elastic modulus without creep correction is significantly over‐estimated, while the creep‐corrected elastic modulus is a constant value (1.25 GPa) which does not change with the test variables. Conversely, the nanohardness extracted by the conventional approach is under‐estimated and the creep‐corrected contact hardness is not constant due to the time‐dependent deformation. The introduction of creep correction factor can significantly simplify the correction calculation process of material parameters. [ABSTRACT FROM AUTHOR]

The local spatial heterogeneity of the material properties of the cortical and trabecular bone extracted from the mouse tibia is not well-known. Nevertheless, its characterization is fundamental to be able to study comprehensively the effect of interventions and to generate computational models to predict the bone strength preclinically. The goal of this study was to evaluate the nanoindentation properties of bone tissue extracted from two different mouse strains across the tibia length and in different sectors. Left tibiae were collected from four female mice, two C57BL/6, and two Balb/C mice. Nanoindentations with maximum 6 mN load were performed on different microstructures, regions along the axis of the tibiae, and sectors (379 in total). Reduced modulus (Er) and hardness (H) were computed for each indentation. Trabecular bone of Balb/C mice was 21% stiffer than that of C57BL/6 mice (20.8 ± 4.1 GPa vs. 16.5 ± 7.1 GPa). Moreover, the proximal regions of the bones were 13–36% less stiff than the mid-shaft and distal regions of the same bones. No significant differences were found for the different sectors for Er and H for Balb/C mice. The bone in the medial sector was found to be 8–14% harder and stiffer than the bone in the anterior or posterior sectors for C57BL/6 mice. In conclusion, this study showed that the nanoindentation properties of the mouse tibia are heterogeneous across the tibia length and the trabecular bone properties are different between Balb/C and C57BL/6 mice. These results will help the research community to identify regions where to characterize the mechanical properties of the bone during preclinical optimisation of treatments for skeletal diseases.

Magnesium matrix nanocomposites (Mg-Sm2O3 nanocomposites in the present study), containing nanosize reinforcements within the magnesium or magnesium alloy matrix, are a group of energy-saving novel material with enhanced strength-to-weight ratio. However, in order to scale up the applications of the magnesium nanocomposites toward industrial dimensions, detailed response of the materials at ambient and elevated temperatures must be established. Having said this, the primary objective of this paper is to obtain an in-depth understanding of small-scale property–microstructure-composition correlation at ambient (298 K) temperature up to 473 K using a depth sensing nanoindentation testing approach as well as advanced microstructural characterization. Mg-Sm2O3 nanocomposites with 0.5, 1.0, and 1.5 vol% Sm2O3 were compared against pure Mg. The properties measured are reduced modulus, elastic modulus, hardness, indentation creep rate, indentation creep exponent, thermal activation volume, as well as indentation size effect as a function of temperature. Pure Mg and Mg-1.0 Sm2O3 nanocomposite provided the least and the greatest creep resistance, respectively. This is attributed to the presence of thermally stable Sm2O3 nanoparticles which can effectively produce dislocation pile-ups and dislocation tangling. [ABSTRACT FROM AUTHOR]

The reduced elastic modulus of a material is measured with a nanoindenter probe that is operated in the tapping mode. The resonant frequency of a freely oscillating cantilever is reduced when contact is made between the indenter tip and surface under investigation. It’s shown using elasticity theory that the elastic deformation is a function of the indenter tip radius. A deeper penetration within the elastic range can change the tip radius, and introduce an error of 10% in calculating the reduced elastic modulus. [ABSTRACT FROM AUTHOR]

For the widely used elastomers, the relationship between modulus and wear resistance was still unclear, which hindered the development of highly wear-resistant materials. In this work, the effect of reduced modulus on abrasive wear behavior of polyurethanes (PUs) was investigated. It demonstrated that at low load, an increase in reduced modulus led to a deteriorated wear resistance due to significant stress concentration. However, at high load, the increased reduced modulus reduced the contact area, and thus improved wear resistance. This was the first time to reveal the dual effect of reduced modulus on wear resistance of elastomers with the change of loads. These findings would contribute to the development of wear-resistant PUs to meet different working conditions. [Display omitted] • At low load, higher reduced modulus caused more wear loss due to high stress concentration. • At high load, the increased modulus decreased the contact area, and thus reduced wear loss. • Reduced modulus had dual effects on wear resistance of PUs with the change of load. [ABSTRACT FROM AUTHOR]

Studies investigating micromechanical properties in mouse cortical bone often solely focus on the mechanical behaviour along the long axis of the bone. Therefore, data on the anisotropy of mouse cortical bone is scarce. The aim of this study is the first-time evaluation of the anisotropy ratio between the longitudinal and transverse directions of reduced modulus and hardness in mouse femurs by using the nanoindentation technique. For this purpose, nine 22-week-old mice (C57BL/6) were sacrificed and all femurs extracted. A total of 648 indentations were performed with a Berkovich tip in the proximal (P), central (C) and distal (D) regions of the femoral shaft in the longitudinal and transverse directions. Higher values for reduced modulus are obtained for indentations in the longitudinal direction, with anisotropy ratios of 1.72 ± 0.40 (P), 1.75 ± 0.69 (C) and 1.34 ± 0.30 (D). Hardness is also higher in the longitudinal direction, with anisotropic ratios of 1.35 ± 0.27 (P), 1.35 ± 0.47 (C) and 1.17 ± 0.19 (D). We observed a significant anisotropy in the micromechanical properties of the mouse femur, but the correlation for reduced modulus and hardness between the two directions is low (r2

Nanoindentation tests were performed on single crystal Ni-based superalloy at temperatures ranging from 20 °C to 800 °C in inert environment. Load-displacement curves at temperatures higher than 500 °C exhibit obvious creep inferred by increasing displacements at load-holding segments. Load-displacement curves obtained at 800 °C also display negative unloading stiffness. Examination of the microstructure beneath the indented area using Transmission Electron Microscope (TEM) reveals abundant dislocation piling up as well as oxide formation on the substrate. A method considering the creep effect is proposed to calculate the reduced modulus. In addition, a dimensionless ratio relating indentation depth and oxide film thickness is introduced to explain the oxidation effect on the mechanical properties derived from the load-displacement curves. [ABSTRACT FROM AUTHOR]

Osteocytes are the main bone cells embedded in the bone matrix where they form a large surface-area network called the lacunar-canalicular network (LCN), interconnecting their resident spaces with the lacunae by the canaliculi. Increasing evidence points toward osteocytes playing a pivotal role in maintaining bone quality. On the one hand, osteocytes transmit mechanical strain and microenvironmental signals through the LCN to regulate the activity of osteoblasts and osteoclasts; on the other hand, osteocytes are suggested to be able to remodel the LCN-associated bone matrix. However, due to the challenges involved in the assessment and characterization of the LCN-associated bone matrix, little is known about its structure and the corresponding mechanical properties. In this work, we used quantitative nanomechanical mapping, backscattered electron imaging, and nanoindentation to characterize the LCN-associated bone matrix. The results show that the techniques can be used to probe the LCN-associated bone matrix. Nanoindentation and quantitative mechanical mapping reveal spatially inhomogeneous mechanical properties of the bone matrix associated with the osteocyte lacunae and canaliculi. The obtained nano-topography and corresponding nano-mechanical maps reveal altered mechanical properties in the immediate vicinity of the osteocyte lacunae and canaliculi, which cannot be explained solely by the topographic change. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

An approximately linear relation between reduced modulus ( E r ) and stiffness ( S ) was observed based on the characterization of completely amorphous Si–C–N hard films by means of nanoindentation. This linear relation was verified by a series of amorphous Si–C–N films prepared under different experimental conditions. Furthermore the linear relation can be extended to amorphous Si–B–C–N film systems. This finding provides one possible way to evaluate the hardness and reduced modulus of a material without involving the contact area. [ABSTRACT FROM AUTHOR]

The notion of reduced modulus of the Riemann sphere with respect to a collection of finite points is extended to the case when the condenser plates are arbitrary continua contracting to these points. It is demonstrated that the reduced modulus is independent of the form of degenerate condenser plates. The reduced modulus was considered earlier in the case when the condenser plates are elements of families of almost disks with fixed centers. [ABSTRACT FROM AUTHOR]

We establish some estimates of the angular derivatives from below for holomorphic self-maps of the unit disk $${\mathbb {D}}$$ at one and two fixed points of the unit circle provided there is no fixed point inside $${\mathbb {D}}$$ . The results complement Cowen-Pommerenke and Anderson-Vasil'ev type estimates in the case of univalent functions. We use the method of extremal length and a semigroup approach to deriving inequalities for holomorphic self-maps of the disk which are not necessarily univalent using known inequalities for univalent functions. This approach allowed us to obtain a new Ossermans type estimate as well as inequalities for holomorphic self-maps which images do not separate the origin and the boundary. [ABSTRACT FROM AUTHOR]

In papermaking, the formation of bonds between single pulp fibers is influenced by the hardness of the fibers in their wet state. In this work, transversal hardness and modulus of pulp fibers have been studied via atomic force microscopy-based nanoindentation in dependence on relative humidity (RH). Additionally, the change in hardness of cellulose and xylan/cellulose model films was also investigated as a function of swelling in the presence of water and calcium chloride (CaCl2) solution. The hardness of pulp fibers is decreasing slowly from 240 MPa at 5% RH to 90 MPa at 80% RH and exhibits a distinct decrease to 2.7 MPa at the fully wet state. The hardness in water is reduced by a factor of almost 100 compared with the dry state; therefore, a form change is easily possible and facilitates the formation of hydrogen bonds on the fiber surfaces. The investigations on the model films reveal that pure cellulose hardens in the CaCl2 solution, compared with distilled water, whereas xylan on cellulose is becoming softer. [ABSTRACT FROM AUTHOR]

We obtain the necessary and sufficient conditions for equality holding in the composition principles for generalized reduced moduli. As an application, we give some descriptions of extremal configurations in known and new inequalities for products of the Robin radii of nonoverlapping domains. [ABSTRACT FROM AUTHOR]

omic force microscopy (AFM) topographical studies and results of nanoindentation experiment for several palladium-carbon films (Pd-C film) deposited on various substrates and with varying palladium content are presented. Pd-C films were prepared by a physical vapor decomposition (PVD) process and next were modified by a chemical vapor decomposition (CVD) method to obtain carbonaceous porous structure with dispersed palladium nanograins and a variation in roughness. The dependence of film topography on the kind of substrate such as AlO, Mo polycrystalline foil and fused silica was studied by AFM. Nanomechanical properties such as hardness and the reduced indentation modulus were determined by nanoindentation. A comparison of these values for films with different Pd content deposited on various substrates is presented. [ABSTRACT FROM AUTHOR]

Mechanical properties of potassium dihydrogen phosphate single crystal (KH2PO4, KDP) at room temperature were investigated using nanoindentation approaches. This study was carried out for two crystallographic planes of KDP single crystal, (001) crystallographic plane and the tripler crystallographic plane. The hardness and the reduced modulus values were calculated by the most commonly used Oliver-Pharr method. It was found that hardness and reduced modulus exhibited significant peak load dependence. Furthermore, the strong anisotropy of the hardness and reduced modulus were observed on two tested surfaces. At the same time, the indentation anisotropy of hardness and reduced modulus on each crystallographic face along different directions were estimated in detail. The results showed that these two faces behave quite differently from each other. The variations of hardness and reduced modulus values for (001) face and the tripler face both were periodic due to the rotational symmetry of crystallographic face microstructure and the indenter shape, and the periods were 90 and 120 degrees, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Welding stresses and deformations are closely related phenomena. During the heating and cooling cycles thermal strains may occur in the weld and adjacent area. The strains produced during the heating stage of welding are always accompanied by plastic deformation of the metal. The stresses resulting from these strains combine and react to produce internal forces that cause a variety of welding distortions. Welding deformation needs to be minimized and also the designer should know before hand the extent of deformation so that it can be accounted for in the design as well as in the construction stages. In this paper, heat sinking as a method of distortion mitigation has been studied. Heat sinking has been affected by circulating water through channel clamped at the bottom surface of the plates undergoing welding. The pseudolinear equivalent constant rigidity concept has been used in this investigation for thermo-mechanical analysis of plates undergoing welding with simultaneous heat sinking. The initial nonlinear problem with varying modulus dependent on temperature is transformed into a pseudolinear equivalent system of constant rigidity that is solved by linear analysis. The numerical results compared very well with those of the experimental ones. The proposed concept is found to be computationally more efficient and simpler to model compared to FEM for solving similar thermo-elasto-plastic nonlinear problems. The procedure presented in this work and the results thus obtained, holds a great promise for determining the heat sinking parameters for effectively controlling welding distortion. [Copyright &y& Elsevier]

Abstract: To ascertain the extent of deformation due to the thermal cycles caused by welding it calls for solving a complex thermal elasto-plastic problem, which is non-linear and involves plastic deformation of the medium at high temperature varying in both time and space. Analytical solutions turned out to be inadequate. At the same time conventional numerical techniques proved to be highly time consuming and thereby prohibitively expensive in real life situations. The concept of pseudolinear equivalent constant rigidity system was developed in this investigation for thermo-mechanical analysis of plates undergoing variation of rigidity due to a continuously changing temperature profile as is encountered in welding situations. The initial non-linear problem with modulus varying with temperature was transformed into a pseudolinear equivalent system of constant rigidity that was solved by applying linear analysis. The numerical results compared very well with those of the experimental ones. The present method was found to be computationally more efficient and simpler to model compared to FEM for solving similar thermo-elasto-plastic nonlinear problems. The analysis procedure presented in this work and the results thus obtained, holds a great promise for analyzing the complicated thermo-elasto-plastic problems as encountered in real life situations. [Copyright &y& Elsevier]

[Display omitted] Classical molecular dynamics (MD) simulations of nanoindentation tests are performed in defect-free at 300, 600 and 1000 K and defected crystals at 300 and 600 K of pure Fe and Fe-9Cr alloy. The aim of the work is to evaluate the effect of the presence of various defects specific to neutron/heavy ion irradiation (i.e., voids, dislocation loops and Cr precipitates) on the material response during the early stages of nanoindentation (i.e., at indentation depths up to 20 Å). We establish that even a relatively large density of the radiation defects (∼1024 m−3) does not induce any significant change in the material response, i.e., it is not unambiguously detectable at the force-depth curves neither in pure Fe nor in Fe-9Cr alloys. The macroscopic parameters, which can be derived from these curves, such as hardness and reduced modulus, calculated in the crystals with and without radiation defects also cannot clearly reveal the contribution from the presence of the radiation defects given the resulting uncertainty of their extraction. However, several distinct features typical for nanoindentation tests observed in crystals with radiation defects only were identified, such as a) obstruction of emission of dislocation loops under the indenter during loading for crystals with precipitates and dislocation loops, and b) special residual imprint pattern for crystals with dislocation loops. The results of this work provide useful data for the parameterization and validation of the higher-scale methods, such as dislocation dynamics and (crystal plasticity-) finite-element method. The details of the transferability of MD results to these methods are also discussed. [ABSTRACT FROM AUTHOR]

We obtain upper bounds for the conformal modulus of a condenser with uniformly perfect plates and for the reduced modulus of a uniformly perfect set E at [InlineMediaObject not available: see fulltext.]. For the reduced moduli of α-uniformly perfect sets we prove the continuity property with respect to the kernel convergence of the complements to these sets in the sense of Carathéodory. [ABSTRACT FROM AUTHOR]

We present a geometric approach to a well-known sharp inequality, due to Cowen and Pommerenke, about angular derivatives of general univalent self-maps of the unit disk. [ABSTRACT FROM AUTHOR]

In this paper, the nanoindentation system and atomic force microscope (AFM) are integrated to improve the limitation of the present area function of nanoindentation test used for shallow depth. The projected areas under the shallow contact depth are modified through scanning directly the immediate vinicity of indenter tip. The results indicate that both indentation hardness and reduced modulus obtained from the proposed method are better than those of the present area function as well as the perfect geometry relation. [ABSTRACT FROM AUTHOR]

Abstract: The effect of various loading levels of nanoclay reinforcement on the nanomechanical properties of layered silicate nanoclay reinforced unsaturated polyester (UPE) nanocomposites were investigated by a nano-indentation test method. The clay was dispersed into a UPE matrix via blending using a mechanical stirrer. Structural studies were carried out using a wide angle X-ray diffraction (WAXD) method and correlated with the nanoindentation results. This shows that nanoindentation behaviour is strongly influenced by clay reinforcement and the degree of clay dispersion in the polymer matrix. The experimental results show that there is a strong correlation between nanomechanical properties and inter layer d-spacing of clay particles in the nanocomposite system. Incorporation of 1%, 3% and 5% by weight nanoclay into the polyester resin results in an improvement in hardness of 29%, 24% and 14%, respectively. The elastic modulus increased from 5393MPa for unreinforced polyester to 6646MPa (23% increase) with the introduction of 5% by weight nanoclay. [Copyright &y& Elsevier]

Abstract: Natural biomaterials have extensively been researched since their distinguished properties adapting to their living surroundings. The cuticle surfaces of bovine hoof and dung beetle directly contact soil when they move on soft ground or in soil. Their surface materials and structures can provide some information for designing soil-engaging components of soft terrain-machines. While, it is difficult to measure their mechanical properties since the cuticle of the bovine hoof wall and dung beetle are very thin. Nanoindenter provides a powerful tool for examining the mechanical properties such as reduced modulus and hardness in nano-scale. The testing methods for nanoindentation properties of the cuticle of the bovine hoof wall and dung beetle (Copris ochus Motschulsky) were discussed in this work. [Copyright &y& Elsevier]

Nanoindentation tests were performed for single crystals of TiO2, MgO, and YSZ (Yttria Satirized Zirconia) using a Berkovich indenter at room temperature. The indentation tests were performed in the load range from 500 to 1500 μN. The area function calibration was performed by using a standard fused SiO2 sample. There is no difference among the reduced moduli of TiO2, MgO, and YSZ, while the nanohardness of YSZ is larger than those of TiO2 and MgO. For YSZ, the reduced modulus along a [1 0 0] direction is larger than that along a [1 1 1] direction, which corresponds to the theoretical estimation using the elastic stiffness constants. [Copyright &y& Elsevier]

The nanoscale mechanical properties such as the reduced modulus and nanohardness of UO2 and (U,Ce)O2 were evaluated. Polycrystalline UO2, UO2 single crystal, UO2 single crystal with (111) plane, and polycrystalline (U,Ce)O2 were selected as the samples. The nanoindentation tests were performed at room temperature in air using the atomic force microscope (AFM) with a nanoindenter. The relationship between nano- and bulk-mechanical properties was studied. [Copyright &y& Elsevier]

A non-uniform heating and cooling cycle caused by a welding or line heating operation leads to deformation. To ascertain the extent of deformation calls for solving a complex thermal elastoplastic problem. In this investigation the concept of a pseudolinear constant stiffness system has been effectively implemented to solve this non-linear problem. The concept has been tested by solving a case of angular deformation of a beam model caused by bead-on-plate welding. The theoretical results compared well with those of the experimental ones. [ABSTRACT FROM AUTHOR]

Alterations to the bone structure from cycle loadings can undermine its damage resistance at multiple scales. The accumulation of fatigue damage in a bone is commonly characterized by the reduction in the elastic modulus. In this study, nano-indentation was used for investigating microscopic damage evolution of bovine tibia samples subjected to fatigue loading. Indentation tests were conducted in the same 60 μm × 120 μm area with different degrees of damage, including fracture, and the evolution of reduced modulus was observed. The results showed that bone's reduced modulus decreased significantly during the initial 40% of the life fraction, whereas it proceeded slowly during the remaining period. As the size of the residual indentations was about 4 μm in length, the degradation of bone's reduced modulus reflected the accumulation of fatigue damage at smaller scales. [ABSTRACT FROM AUTHOR]

We consider Mityuk's function and radius which have been proposed in [15] as generalizations of the reduced modulus and conformal radius to the cases of multiply connected domains. We present a numerical method to compute Mityuk's function and radius for canonical domains that consist of the unit disk with circular/radial slits. Our method is based on the boundary integral equation with the generalized Neumann kernel. Special attention is given to the validation of the theoretical results on the existence of critical points and the boundary behavior of Mityuk's radius. [ABSTRACT FROM AUTHOR]

The local spatial heterogeneity of the material properties of the cortical and trabecular bone extracted from the mouse tibia is not well-known. Nevertheless, its characterization is fundamental to be able to study comprehensively the effect of interventions and to generate computational models to predict the bone strength preclinically. The goal of this study was to evaluate the nanoindentation properties of bone tissue extracted from two different mouse strains across the tibia length and in different sectors. Left tibiae were collected from four female mice, two C57BL/6, and two Balb/C mice. Nanoindentations with maximum 6 mN load were performed on different microstructures, regions along the axis of the tibiae, and sectors (379 in total). Reduced modulus ( Er ) and hardness ( H ) were computed for each indentation. Trabecular bone of Balb/C mice was 21% stiffer than that of C57BL/6 mice (20.8 ± 4.1 GPa vs. 16.5 ± 7.1 GPa). Moreover, the proximal regions of the bones were 13-36% less stiff than the mid-shaft and distal regions of the same bones. No significant differences were found for the different sectors for E r and H for Balb/C mice. The bone in the medial sector was found to be 8-14% harder and stiffer than the bone in the anterior or posterior sectors for C57BL/6 mice. In conclusion, this study showed that the nanoindentation properties of the mouse tibia are heterogeneous across the tibia length and the trabecular bone properties are different between Balb/C and C57BL/6 mice. These results will help the research community to identify regions where to characterize the mechanical properties of the bone during preclinical optimisation of treatments for skeletal diseases., (Copyright © 2020 Pepe, Oliviero, Cristofolini and Dall'Ara.)