Indentation Area Research Articles

On elastoplastic behavior of porous enamel–An indentation and numerical study

The micro/nano pores in natural mineralized tissues can, to a certain extent, affect their responses to mechanical loading but are generally ignored in existing indentation analysis. In this study, we first examined the void volume fraction of sound and caries lesion enamels through micro-computed tomography (micro-CT). A Berkovich indentation study was then carried out to characterize the effect of porous microstructure on the mechanical behavior of the human enamels. The indentation tests were also modeled using the nonlinear finite element analysis technique to simulate indentation load-displacement curves, which showed reasonable agreement with the experimental measurements. From the simulation results, the extent of densification in the plastic zone was identified and the corresponding stress and contact pressure evolutions were quantified. Further, a conventional elastic-perfectly plastic material model without considering micropores was also developed to investigate the compaction effect of the porous structure. The simulation results reveal that conventional elastic perfect-plastic constitutive models become less reliable to model the mechanical behavior of carious lesion enamel with increasing loss of mineral content as it underestimates the yield stress and plastic energy dissipation. This study divulges the importance of compaction of porous enamel structure beneath the indented area. Note that understanding the effect of porous microstructures on plastic behavior is vital as the involved inelastic deformation mechanism associated with irreversible processes, such as wear and localized microcracking, has a significant bearing on wear and fatigue behavior of enamel. Statement of significanceBased on micro-CT and nano-indentation characterization, a numerical model was developed aiming to precisely describe the deformation behavior of naturally porous enamel. Inelastic properties and energy dissipation characteristics of porous enamel were investigated in detail. This work demonstrated that the existence of micro-pores in White Spot Lesions (WSLs) contributes to mechanical stability, which can mitigate the reduction in Young's modulus and fracture toughness resulting from loss of mineral components. The knowledge gained from this study can be used to explain the mechanisms related to irreversible processes, such as contact induced cracking and wear, and strengthen understanding of the mechanical behavior of porous mineralized tissues.

Dissolvable microneedles in the skin: Determination the impact of barrier disruption and dry skin on dissolution

Dissolvable microneedles (DMNs), fabricated from biocompatible materials that dissolve in both water and skin have gained popularity in dermatology. However, limited research exists on their application in compromised skin conditions. This study compares the hyaluronic acid-based DMNs penetration, formation of microchannels, dissolution, and diffusion kinetics in intact, barrier-disrupted (tape stripped), and dry (acetone-treated) porcine ear skin ex vivo. After DMNs application, comprehensive investigations including dermoscopy, stereomicroscope, skin hydration, transepidermal water loss (TEWL), optical coherence tomography (OCT), reflectance confocal laser scanning microscopy (RCLSM), confocal Raman micro-spectroscopy (CRM), two-photon tomography combined with fluorescence lifetime imaging (TPT-FLIM), histology, and scanning electron microscopy (SEM) were conducted. The 400 µm long DMNs successfully penetrated the skin to depths of ≈200 µm for dry skin and ≈200–290 µm for barrier-disrupted skin. Although DMNs fully inserted into all skin conditions, their dissolution rates were high in barrier-disrupted and low in dry skin, as observed through stereomicroscopy and TPT-FLIM. The dissolved polymer exhibited a more significant expansion in barrier-disrupted skin compared to intact skin, with the smallest increase observed in dry skin. Elevated TEWL and reduced skin hydration levels were evident in barrier-disrupted and dry skins compared to intact skin. OCT and RCLSM revealed noticeable skin indentation and pronounced microchannel areas, particularly in barrier-disrupted and dry skin. Additional confirmation of DMN effects on the skin and substance dissolution was obtained through histology, SEM, and CRM techniques. This study highlights the impact of skin condition on DMN effectiveness, emphasizing the importance of considering dissolvability and dissolution rates of needle materials, primarily composed of hyaluronic acid, for optimizing DMN-based drug delivery.

Mechanical Response of Cu/Sn58Bi-xNi/Cu Micro Solder Joint with High Temperatures

Sn58Bi solder is considered a promising lead-free solder that meets the performance requirements, with the advantages of good wettability and low cost. However, the low melting point characteristic of Sn58Bi poses a serious threat to the high-temperature reliability of electronic products. In this study, Sn58Bi solder alloy based on nickel (Ni) functionalization was successfully synthesized, and the effect of a small amount of Ni on creep properties and hardness of Cu/Sn58Bi/Cu micro solder joints at different temperatures (25 °C, 50 °C, 75 °C, 100 °C) was investigated using a nanoindentation method. The results indicate that the nanoindentation depth of micro solder joints exhibits a non-monotonic trend with increasing Ni content at different temperatures, and the slope of the indentation stage curve decreases at 100 °C, showing that the micro solder joints undergo high levels of softening. According to the observation of indentation morphology, Ni doping can reduce the indentation area and accumulation around the indentation, especially at 75 °C and 100 °C. In addition, due to the severe creep phenomenon at 100 °C, the indentation hardness rapidly decreases. The indentation hardness values of micro solder joints of Cu/Sn58Bi/Cu, Cu/Sn58Bi-0.1Ni/Cu, and Cu/Sn58Bi-0.2Ni/Cu at 100 °C are 14.67 ± 2.00 MPa, 21.05 ± 2.00 MPa, and 20.13 ± 2.10 MPa, respectively. Nevertheless, under the same temperature test conditions, the addition of Ni elements can improve the high-temperature creep resistance and hardness of Cu/Sn58Bi/Cu micro solder joints.

Mechanism of dentin hardness measurements using a dentin hardness measuring device with a light-emitting diode.

Managing caries is imperative in a rapidly aging society. Current diagnoses use qualitative indices. However, a quantitative evaluation of hardness in a clinical setting may lead to more accurate diagnoses. Previously, hardness meter using indenter with light for tooth monitoring (HAMILTOM) was developed to quantitatively measure tooth hardness. Herein, the physical interpretation of dentin hardness measured using HAMILTOM and the dentin hardness measurement mechanism are discussed. This study evaluates the mechanism of dentin hardness measurements using HAMILTOM physically and compare the invasiveness to dentin by HAMILTOM with those using a dental probe for palpation. Eleven bovine dentin samples were used to create caries models. HAMILTOM measured the dark areas, and its indentations were observed using scanning electron microscopy. Also, its invasiveness was evaluated by comparing the results with those from dental probe palpation. The indentation areas were smaller than the dark areas in HAMILTOM, which may be due to exuded water from the dentin sample and the elastic recovery of dentin sample. Additionally, the dental probe indentation was deeper than the HAMILTOM indentations. The results demonstrate that the indentation areas were smaller than the dark areas measured by HAMILTOM, which might contain the influence of exuded water and the deformation of dentin sample. Also, HAMILTOM is less invasive than dental probe palpation. In the future, HAMILTOM may become a standard hardness measuring method to diagnose root caries.

Study of nanoindentation behavior of NiCrCoAl medium entropy alloys under indentation process using molecular dynamics

Abstract The mechanical properties and deformation behavior of CoCrNiAl medium entropy alloy (MEA) subjected to indentation by an indenter tooltip on the substrate are explored using molecular dynamics (MD) simulation. The study investigates the effects of alloy compositions, temperature variations, and ultra vibration (UV) on parameters, such as total force, shear strain, shear stress, hardness, reduced modulus, substrate temperature, phase transformation, dislocation length, and elastic recovery. The findings indicate that higher alloy compositions result in increased total force, hardness, and reduced modulus, with Ni-rich compositions demonstrating superior mechanical strength. Conversely, increasing alloy compositions lead to reduced von Mises stress (VMS), phase transformation, dislocation distribution, and dislocation length due to the larger atomic size of Ni compared to other primary elements. At elevated substrate temperatures, atoms exhibit larger vibration amplitudes and interatomic separations, leading to weaker atomic bonding and decreased contact force, rendering the substrate softer at higher temperatures. Additionally, higher initial substrate temperatures enhance atom kinetic energy and thermal vibrations, leading to reduced material hardness and increased VMS levels. Increasing vibration frequency enlarges the indentation area on the substrate’s surface, concentrating shear strain and VMS with vibration frequency. Higher vibration amplitude and frequency amplify force, shear strain, VMS, substrate temperature, and dislocation distribution. Conversely, lower vibration amplitude and frequency result in a smaller average elastic recovery ratio. Moreover, increased amplitude and frequency values yield an amorphous-dominated indentation region and increased proportions of hexagonal close-packed and body-centered cubic structures. Furthermore, this study also takes into account the evaluation of a material’s ability to recover elastically during the indentation process, which is a fundamental material property.

Investigation on micro region deformation of residual indents during temperature recovery

Observation of residual indent is widely adopted to evaluate the mechanical properties of material in temperature indentation test. However, the potential influence of the difference between the testing and observing temperatures on the material is always neglected. In this study, crystal plasticity finite element model of copper was constructed, and the processes of high-temperature indentation test and specimen temperature reduction to the observed temperature after the test were simulated. The simulations showed that the error of test hardness can reach up to 4.92% as the residual indent area decreases with temperature decreasing from 800 °C to 20 °C. The stress values of the indentation influence zone were also reduced considerably, in which the maximum stress at 20 °C was 59% of that at 800 °C. The distribution of stresses at surface and subsurface both changed substantially, while the depth of the influence zone increased by 31%. The mechanical properties of material were also found to affect the micro region deformation of residual indents during temperature recovery. Therefore, the influence of temperature variation between the testing and observing processes on residual indent should be seriously considered.

ПОВРЕЖДАЕМОСТЬ ЦИЛИНДРИЧЕСКОЙ ОБОЛОЧКИ В ПРОЦЕССЕ ЕЕ ИНЕРЦИОННОГО СХОЖДЕНИЯ

The mechanisms behind damage to cylindrical shells during inertial convergence are investigated in this article. As solids are subjected to increasing pressures and temperatures during this convergence, they develop a distinct wavy texture on the outer surface, consisting of raised and indented areas. The shape of the protrusions confirms its hydrodynamic origin. The behaviour of the shells is similar to that of cylindrical solid samples in the final stage of convergence.

Does glaze firing affect the strength of advanced lithium disilicate after simulated defects?

ObjectiveTo study the influence of glazing on strength repair of lithium disilicate glass–ceramics after defect incorporation in different production processing phases.Materials and methodsBar-shaped specimens (1 × 1 × 12 mm, n = 280; 20/group) made from different lithium disilicate ceramics (IPS e.max CAD, Ivoclar, “LD” or advanced lithium disilicate CEREC Tessera, Dentsply Sirona, “ALD”) were exposed to 7 different protocols: crystallized without (c) and with glaze layer (cg), with a defect incorporated before crystallization without (ic) and with glaze layer (icg), with a defect after crystallization without (ci) or with glaze layer (cig), and defect incorporated after the glaze layer (cgi). The flexural strength was determined using the three-point bending test. Analysis of indented areas and fractured specimens was performed by scanning electron microscopy. Flexural strength data were evaluated by two-way ANOVA followed by Tukey tests (α = 5%).ResultsTwo-way ANOVA revealed a significant influence of ceramic (p < 0.001; F = 55.45), protocol (p < 0.001; F = 56.94), and the interaction protocol*ceramic (p < 0.001; F = 13.86). Regardless of ceramics, defect incorporation as final step resulted in the worst strength, while defects introduced before crystallization did not reduce strength. Glaze firing after defect incorporation led to strength repair for ALD, whereas such an effect was not evident for LD.ConclusionsThe advanced lithium disilicate must receive a glaze layer to achieve its highest strength. Defects incorporated in the pre-crystallized stage can be healed during crystallization. Defects should not be incorporated after glazing.Clinical relevanceClinical adjustments should be performed on pre-crystallized or crystalized restorations that receive a glazer layer afterwards.

Amorphization of gold film on silicon single crystal by hardness indentation at room temperature

ABSTRACT The formation of an amorphous gold-silicon alloy by indentation is reported. A polycrystalline gold film formed via vapour deposition on a silicon (111) substrate was indented using a Berkovich indenter with a load of 0.05 N. The indentation area was observed by transmission electron microscopy after thinning the silicon substrate from the back side (unindented surface). A set of halo rings, identified as an amorphous gold-silicon alloy was observed. A gold film on a SiO2 substrate was also used to investigate the effect of the substrate, and no amorphization was observed. The amorphization mechanism is discussed based on thermodynamics.

Challenges of reliable AFM-tip shape reconstruction and approximation.

Reliable reconstruction of AFM tip geometry is not an easy task. The shape of the tip can be (partially) reconstructed from the AFM image of a calibration sample using a blind reconstruction method. The result is a range of the tip shapes (from unrealistically sharp to blunt). A criterion for selecting the true shape is proposed. It is based on reconstruction of the calibration relief. Further refining the probe geometry by indenting an elastic polymer is discussed. The choice of the test sample is another problem. In practice, the researcher has a small number of commercially available test gratings. Their limitations are highlighted. An approximation of tip geometry by a body of revolution is required in indentation experiments. A hyperboloid was found to be the closest approximation to the conventional probes. The contact area was obtained for the hyperboloids with different parameters indenting an elastic material. RESEARCH HIGHLIGHTS: Criteria for blind reconstruction algorithm of AFM tip shape. Pros and cons of tip shape calibration samples. Contact area of the elastic indentation by hyperbolic indenter.

Effect of impactor velocity on low velocity impact behavior of Al/SiC monocoque interpenetrating composites

This study investigates the impact behavior and energy absorption characteristics of C4 composites under different initial energy conditions. The force-displacement responses were recorded using a conical impactor on an impact testing machine. Three configurations of C4 composites with varying pore sizes (10PPI, 20PPI, and 30PPI) were tested at three initial impact energies (208 J, 312 J, and 416 J). The force-displacement curves revealed that the 30PPI-C4 exhibited the highest force gradient and maximum force, followed by the 20PPI-C4 and 10PPI-C4. The maximum force increased with increasing impact energy for all configurations. Velocity attenuation during impact tests showed a correlation with deformation and collapse mechanisms of the C4 composite. Energy absorption analysis indicated that the 30PPI-C4 exhibited the highest energy absorption per unit mass, followed by the 20PPI-C4 and 10PPI-C4. Visual inspection revealed circular indentations and shear cracks on the top and bottom surfaces, with increasing damage area and depth of indentation at higher impact energies. The 30PPI-C4 demonstrated better resistance to indentation and failure, along with higher specific energy absorption. The refined grains in the 30PPI-C4 contributed to crack mitigation and energy absorption. The C4 composites with higher SiC volume percentages exhibited reduced damage area and higher stability during impact tests. The study concludes that the 30PPI-C4 composite with 18 vol% SiC foam shows superior impact resistance and energy absorption properties, making it a promising material for impact-related applications.

Application of spherical macro-indentation for determination of plastic anisotropy and residual stresses using indentation geometry and inverse analysis

The simultaneous determination of mechanical properties and residual stresses using the instrumented indentation technique is more challenging when the anisotropic behaviour of a material is considered. If ignored, it may lead to inaccurate estimation of residual stresses and mechanical properties of materials. In this paper, the existence of in-plane anisotropic plasticity and the equi-biaxial residual stresses were considered in materials simultaneously. These anisotropic plastic properties and residual stresses were extracted for two materials, an aluminium alloy and a stainless steel, using an inverse analysis method and macro-spherical indentation test. The considered anisotropic materials have different yield stresses in both the longitudinal and transverse directions of the part. The inverse analysis method was based on a wide range of finite element (FE) simulations, which included a large number of models covering the properties of different steel and aluminium materials. In this method, the parameters extracted from the load-displacement (P-h) curve for indentation, along with the pile-up around the indentation area after unloading, were considered as the input parameters of the inverse analysis method. The outputs were the mechanical properties of the anisotropic material and the equi-biaxial tensile and compressive residual stresses. The proposed inverse method was based on the analysis of the artificial neural network (ANN). The effectiveness of the inverse method was examined and verified using experimental data which were found to be reliable. The method employed the P-h curve parameters and unloading morphology and was successful to determine the anisotropic plastic properties and residual stresses.

Intelligent Testing and Analysis of Dissimilar Steel Welds for Industrial Throttle Flowmeter

The throttling flowmeter used in utility boilers has been used as a measuring instrument for a long time. However, its safety performance, such as welding, lacks enough attention. The manufacturing welds of the throttling flowmeter are welded with austenitic stainless steel and pearlitic heat-resistant steel. Cracks and other defects are generally found in the inspection and detection of the manufacturing welds of throttling flowmeters in service, which have serious potential accidents. To find out the relationship between weldingdissimilar steels and defects, the microhardness indentation method was used to measure the residual stress of welding. Combined with the self-developed calculation software of microscopic indentation residual stress distribution, we used the difference between the color of the indentation area and the surrounding area to quickly measure the indentation strain collected by the microscope using the computer image recognition algorithm, which greatly improved the accuracy and speed of the microscopic indentation residual stress test. The results show that the residual stress at the weld of dissimilar steel is relatively large, and the mechanical property test is generally unqualified. The microindentation residual stress analysis method based on computer image recognition is used to quickly, intuitively, and accurately reveal the direct relationship between the combination of dissimilar steel welding materials and the generation of cracks and other defects.

Damage evolution of the coating/substrate system TiN/X2CrNi18-9 under high indentation loads: experimental and numerical study

Hard coatings, in particular TiN, are widely used as coatings for cutting tools and in the agri-food industry. In the literature, however, few characterizations of hard coatings can be found which define the minimum applied load when the coating starts to fail. In the present study TiN coating was deposited on stainless steel X2CrNi18-9. Vickers and Brinell indentation tests with a wide load range were performed. The main results revealed that the increase of the applied load in Vickers and Brinell indentation influenced the coating and coating/substrate damage evolution. SEM investigation of the Vickers indentation area shows five modes of damage: inclined cracks, radial cracks, lateral cracks, edge cracks, and shear steps. Each damage mode occurs at a specific load range. Parallel cracks already appeared at the edges of the indents at the lowest load of 2 N. For Brinell indentation, cracks start in the coating only at loads higher than F = 307 N. The SEM examinations present damage modes such as circumferential cracks in the border and additional circular cracks in the center of the indent, creating a crack network. Numerical simulations of Brinell indentation were carried out in order to determine the stress distribution in the indent. The comparison of the numerical simulation results with the experimental findings revealed that the coating started to fail at a stress range above 5735 MPa which corresponds to a normal load range of higher than 307 N in Brinell indentation tests. At a load of 613 N cracks were observed.

Influence of water and protein content on the creep behavior in dental enamel.

The creep behavior of untreated and deproteinized dental enamel in dry and wet state was analyzed by nanoindentation with a spherical tip. Additionally, the influence of the loading rate was investigated. Dry untreated and deproteinized dental enamel only showed minor creep over 100s and deproteinization did not affect the dry enamel's behavior significantly. With slower loading rates some creep already occurs during the loading period, such that the creep displacement during load hold is less than with faster loading rates. Wet untreated and deproteinized enamel showed significantly more creep compared to the dry samples. The differences between the untreated and deproteinized enamel were only minor but significant, revealing that water affects the creep behavior of biological materials such as enamel significantly. The proposed deformation mechanism of naturally porous enamel under compression is compaction of the HAP crystallites and fluid displacement within material underneath the indented area. STATEMENT OF SIGNIFICANCE: This study investigates the creep behavior of untreated and deproteinized dental enamel in dry and wet conditions. It is shown that while the protein content does not affect enamel's behavior significantly, the wet conditions lead to an increased creep in enamel. The proposed deformation mechanism of naturally porous enamel under compression is compaction of the HAP crystallites and fluid displacement within material underneath the indented area. Based on this observation a simple analytical model has been developed, aiming to deepen our understanding of the deformation behavior of biological materials.

Effect of Liquid Metal Embrittlement Indent Cracks on Zinc Coated 3rd Generation AHSS Mechanical Performance

Third-generation advanced high-strength steels (3G-AHSS) are typically galvanized to prevent corrosion of the outer body structure. However, the zinc coating on the surface, combined with the locally elevated temperatures generated during the resistance spot welding (RSW) process, can provide the prerequisites for liquid metal embrittlement (LME). This work uses two strategies to control LME crack formation: current pulsation and varying the electrode geometry. These two methods were compared to a baseline welding schedule for a 3G-980-GI coated AHSS. The effectiveness of each method was discussed in terms of the overall weld cracking index and local cracking index. The results showed that increasing the current pulses results in a slower energy input into the weld, which can help to reduce LME crack formation. Introducing more pulses (five to seven pulses) reduced LME crack formation while maintaining the same welding time. Regarding the electrode geometry, the results showed an increase in LME cracking index for currents below the expulsion level Imax-10% when the electrode face diameter increased, whereas at the current level Imax-200A, the electrode radius was the most important factor to control LME crack index. For the current level above the expulsion, Imax+10%, a drastic decrease in the LME cracking index was observed when a large electrode surface diameter was used. The electrode radius was not a significant factor in controlling LME. The mechanical properties of selected conditions were examined using the lap shear test and the results showed no significant effect of LME cracks on the shear tensile strength. The location of the failure indicated that most of the cracks are located in the indented area (type A), which does not influence the lap shear strength.

Characterization of mechanical properties of five hot-pressed lignins extracted from different feedstocks by microscopy-aided nanoindentation

Lignin, a main component of plants, is produced in large quantities as a by-product of the pulp and papermaking industry. The abundance of this organic polymer makes it an excellent candidate for developing renewable materials such as lignin-based biocomposites. The mechanical properties of lignin, as well as the dependence on the extraction process and feedstock, are, however, still unknown and hamper its utilization. Therefore, five hot-pressed lignins, extracted by different processes from different feedstocks, are tested by means of grid nanoindentation at indentation depths ranging from 150 nm to 1200 nm. Statistical and microstructure-guided evaluation based on microscopy images of the indented areas allows for retrieving reliable indentation properties of the porous lignin, free of indentation size effects. The sought mechanical properties of the solid (pore-free) lignin are back-identified from the strong correlation between the property and the porosity using micromechanics homogenization theory. This correlation reveals that the solid lignin in all tested samples is mechanically similar, despite different chemical structures, with a virtually intrinsic Young’s modulus of 7.1 GPa.

Response of axial-loaded steel-concrete composite walls under low-velocity impact

Steel-concrete (SC) composite walls consisting of two external steel plates and sandwiched concrete core have been employed in various engineering structures such as nuclear facilities, protective structures and high-rise buildings. Impact resistance performance is an important aspect for designing this type of structures. This paper experimentally and numerically studies the low-velocity impact response of axial-loaded SC composite walls. A total of six SC composite walls were fabricated and tested by using drop hammer to obtain damage mode, impact force and mid-span deformation. Effects of impact height (impact energy), steel plate thickness, shear connector type and axial-load ratio were analyzed. The specimens experienced severe local indentation at the impact location. As the axial-load level increased from 0 to 0.2, the indentation area, concrete cracking and global deformation was reduced, indicating the axial-load could effectively enhance the impact-resistant capacity of the SC walls. Additionally, finite element (FE) models were developed and validated using test data. The verified numerical models were then employed to analyze the impact process and energy dissipation mechanism as well as the influences of key parameters on the dynamic responses. After that, a simplified formula was suggested to estimate the maximum mid-span deformation of SC composite walls under impact loading.

Characterization of intra-tissue strain fields in articular cartilage explants during post-loading recovery using high frequency ultrasound

This study aims to demonstrate the potential of ultrasound elastography as a research tool for non-destructive imaging of intra-tissue strain fields and tissue quality assessment in cartilage explants. Osteochondral plugs from bovine patellae were loaded up to 10, 40, or 70 N using a hemi-spherical indenter. The load was kept constant for 15 min, after which samples were unloaded and ultrasound imaging of strain recovery over time was performed in the indented area for 1 h. Tissue strains were determined using speckle tracking and accumulated to LaGrangian strains in the indentation direction. For all samples, strain maps showed a heterogeneous strain field, with the highest values in the superficial cartilage under the indenter tip at the bottom of the indent and decreasing values in the deeper cartilage. Strains were higher at higher load levels and tissue recovery over time was faster after indentation at 10 N than at 40 N and 70 N. At lower compression levels most displacement occurred near the surface with little deformation in the deep layers, while at higher levels strains increased more evenly in all cartilage zones. Ultrasound elastography is a promising method for high resolution imaging of intra-tissue strain fields and evaluation of cartilage quality in tissue explants in a laboratory setting. In the future, it may become a clinical diagnostic tool used to identify the extent of cartilage damage around visible defects.

Nano-scale mechanical properties of constituent minerals in shales investigated by combined nanoindentation statistical analyses and SEM-EDS-XRD techniques

The mechanical properties of the constituent minerals in shale rock are fundamental to a better knowledge of multi-scale shale behaviors. It benefits the engineering applications and predictive physics modeling of the shale formation . In this work, nanoindentation testing combined with scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS) were used to obtain the in situ mechanical properties of individual mineral phases in four shale samples. Engraved cross-marks were employed to locate the indented areas on a micron scale for subsequent SEM-EDS measurements and analysis. The elastic moduli and hardness of the quartz, iron-type minerals, muscovite , clinochlore , organic matter, and the mineral assortments in the matrix were analyzed and relevant deformative behaviors were compared. Results show that the identified mineral groups exhibit a diverse set of mechanical properties at the nanoscale . The iron-type minerals have the highest elastic modulus (104.7 GPa), then followed by quartz, muscovite, clinochlore, and organic matter. Quartz shows the highest hardness (10.2 GPa). The identified minerals demonstrated different elasto-plastic characteristics to the indentation loads. Quartz exhibits the lowest plastic behavior, while phyllosilicates exhibited large plastic behavior owing to the layered structure. Organic matter showed both elastic-dominant and plastic-dominant behaviors, which may be related to the chemical compositional differences and various thermal maturity of kerogen in the shale samples. The mechanical properties of three mineral assortments in shale matrices vary significantly due to the wide variety of the mineral compositions. Radial cracks were observed on the boundary of brittle minerals and relatively weak minerals, while shear cracks were observed on strength-weak minerals such as layered silicates and organic matters. The mechanism of the induced cracks was discussed. This study obtains a basic understanding of shale behavior on nano-scale and provides reliable basic data for multi-scale modeling of shale reservoirs without the need for large-scale mechanical tests.