Significant Strain Gradients Research Articles

Flexoelectricity Modulated Electron Transport of 2D Indium Oxide.

The phenomenon of flexoelectricity, wherein mechanical deformation induces alterations in the electron configuration of metal oxides, has emerged as a promising avenue for regulating electron transport. Leveraging this mechanism, stress sensing can be optimized through precise modulation of electron transport. In this study, the electron transport in 2D ultra-smooth In2O3 crystals is modulated via flexoelectricity. By subjecting cubic In2O3 (c-In2O3) crystals to significant strain gradients using an atomic force microscope (AFM) tip, the crystal symmetry is broken, resulting in the separation of positive and negative charge centers. Upon applying nano-scale stress up to 100nN, the output voltage and power values reach their maximum, e.g. 2.2mV and 0.2pW, respectively. The flexoelectric coefficient and flexocoupling coefficient of c-In2O3 are determined as ≈0.49nCm-1 and 0.4V, respectively. More importantly, the sensitivity of the nano-stress sensor upon c-In2O3 flexoelectric effect reaches 20nN, which is four to six orders smaller than that fabricated with other low dimensional materials based on the piezoresistive, capacitive, and piezoelectric effect. Such a deformation-induced polarization modulates the band structure of c-In2O3, significantly reducing the Schottky barrier height (SBH), thereby regulating its electron transport. This finding highlights the potential of flexoelectricity in enabling high-performance nano-stress sensing through precise control of electron transport.

Study on the strain partitioning behavior in heterostructured complex-concentrated alloy via high-resolution digital image correlation

Here, we investigate the tensile deformation behavior in a Ni42Fe30Cr12Mn8Al5Ti3 complex-concentrated alloy with heterogeneously-grained structure consisting of fine and ultrafine grains containing nano-sized L12 precipitates. It is found that Lüders band initiation and propagation account for the early stage of deformation. High-resolution digital image correlation investigation reveals that there is strong strain partitioning between fine and ultrafine-grained domains upon plastic deformation. Significant strain gradient across the domain-interfaces is thus established. Strain partitioning promoted dense microshear bands are observed in the deformed alloy. They are uniformly distributed and interacted with each other, resulting in the formation of strain concentration zones, which are mostly evolved in fine-grained domains and some of them extend into ultrafine-grained domains at high strain levels. Thus, the global plastic deformation of the alloy is synergistically accommodated. Finally, local high stress in strain concentration zones in ultrafine-grained domains promotes the formation of voids at triple junctions of grain boundaries.

Microstructure-dependent deformation mechanisms and fracture modes of gradient porous NiTi alloys

Gradient porous structures based on triply periodic minimal surfaces offer exceptional specific strength and multi-functionality. However, strain heterogeneity complicates their deformation mechanisms and fracture modes. In this study, we fabricated a series of gradient porous NiTi alloys based on gyroid (G), diamond (D), and I-WP (I) unit cells, with porosities ranging from 50% to 70%. Surprisingly, the I structure exhibited an abnormally high compressive strength of nearly 600 MPa at around 50% porosity, more than twice that of the G and D structures. This performance gap was attributed to the activation of mixed deformation mechanisms and distinct fracture modes. While the G structure showed a uniform radial strain distribution, the D and I structures displayed pronounced radial strain gradients with concentrated central strains. The D structure deformed through relative sliding of oblique struts, while the I structure maintained macrostructural stability, with thick edge struts providing continuous strain hardening until monolithic fracture. This unique deformation behavior results from the synergistic effects of its intrinsic macrostructural stability, significant radial strain gradients, and sufficiently thicker edge struts. The integration of metallurgical and architectural design principles represents a novel approach to tailoring the mechanical properties of gradient porous metals for advanced applications.

Anisotropic functionally graded nano-beam models and closed-form solutions in plane gradient elasticity

This study delves into the investigation of exact analytical solutions for the plane stress and displacement fields within linear homogeneous anisotropic nano-beam models of gradient elasticity. It focuses on solving the Helmholtz equation, which encompasses a second-order non-homogeneous linear partial differential equation in plane gradient elasticity theory, utilizing polynomial series-type solutions. The analysis centers on the utilization of gradient Airy stress functions to derive stress fields in the gradient theory. The research yields closed-form analytical solutions for Airy stress functions, stress, and strain fields in both classical and gradient theories. The study considers five distinct types of two-dimensional functionally graded cantilever beams with various boundary conditions: a cantilever anisotropic nano-beam subjected to a concentrated force at the free end, a cantilever anisotropic nano-beam under a uniform load, a simple anisotropic nano-beam under a uniform load, a propped cantilever anisotropic nano-beam under a uniform load, and a fixed end cantilever anisotropic nano-beam under a uniform load. General analytical solutions for the gradient stress and displacement fields of two-dimensional and one-dimensional anisotropic nano-beams under different boundary conditions are provided. The study showcases significant strain gradient size effects at the nano-scale through the derived analytical solutions for anisotropic beams. Additionally, it demonstrates that the strain gradient theory results for the limit case of the gradient coefficient c precisely align with results for isotropic and anisotropic materials in elasticity theory and classical theory. Furthermore, real-world applications are discussed, considering stress and displacement fields in real anisotropic materials such as TiSi2 single crystals and orthotropic materials, which are special cases of anisotropic materials like wood and epoxy as documented in the literature.

Revealing the Enhancement Mechanism of Laser Cutting on the Strength–Ductility Combination in Low Carbon Steel

The strength–ductility mechanism of the low-carbon steels processed by laser cutting is investigated in this paper. A typical gradient-phased structure can be obtained near the laser cutting surface, which consists of a laser-remelted layer (LRL, with the microstructure of lath bainite + granular bainite) and heat-affected zone (HAZ). As the distance from the laser cutting surface increases, the content of lath martensite decreases in the HAZ, which is accompanied by a rise in the content of ferrite. Considering that the microstructures of the LRL and HAZ are completely different from the base metal (BM, ferrite + pearlite), a significant strain gradient can be inevitably generated by the remarkable microhardness differences in the gradient-phased structure. The hetero-deformation-induced strengthening and hardening will be produced, which is related to the pileups of the geometrically necessary dislocations (GNDs) that are generated to accommodate the strain gradient near interfaces. Plural phases of the HAZ can also contribute to the increment of the hetero-deformation-induced strengthening and hardening during deformation. Due to the gradient-phased structure, the low carbon steels under the process of laser cutting have a superior combination of strength and ductility as yield strength of ~487 MPa, tensile strength of ~655 MPa, and total elongation of ~32.7%.

Microstructural origin of high strength and high strain hardening capability of a laser powder bed fused AlSi10Mg alloy

Compared to a cast AlSi10Mg alloy, a laser powder bed fused (LPBF) AlSi10Mg alloy shows superior yield strength and strain hardening capability. However, the underlying microstructure origin has not been comprehensively understood. In this work, the microstructural evolution of an LPBF AlSi10Mg alloy during tensile deformation was investigated. Synchrotron X-ray diffraction characterization shows that both stress and strain exhibit significant partition between an Al phase and a Si phase upon tensile deformation. This leads to a significant strain gradient between those two phases, which is evident by the high density of dislocations in the cell boundaries of the deformed alloy. The strain gradient results in long-range internal stress, also known as back stress, in the cell boundaries, and in turn leads to enhanced strength and strain hardening in the LPBF AlSi10Mg alloy. Quantitatively analyses via loading-unloading-reloading tests show that during the tensile deformation, the back stress contributes 135 MPa to the yield strength of the alloy, which continuously increases with increasing the strain beyond the yielding point. This work illuminates the microstructural origin of the back stress in the LPBF AlSi10Mg alloy, i.e. the back stress arises from the stress/strain partition between the Al and Si phases in the cellular structures, and the back stress leads to significant strengthening of the alloy upon tensile deformation. This work may also provide guidance for manipulating the mechanical properties of additively manufactured Al-Si alloys for specific application needs.

Significantly improve the strength and ductility of AZ31 Mg alloy by introducing pure Ti

In this work, we introduced pure Ti into AZ31 Mg alloy by extrusion process followed by annealing at 350 °C for 1 h to significantly improve the mechanical properties of AZ31 laminate, with a yield strength of 243 MPa, an ultimate tensile strength of 338 MPa and a uniform elongation of 17.7%. Microstructural characterizations showed that there was slight diffusion of elements (Al, Zn, and Mn) across the layer interface, and the interface between the constituent layers maintained semi-coherent. Moreover, significant microstructure heterogeneities appeared across the hetero-interface, where the Mg layer possessed large equiaxed grains with lower dislocation density, while the Ti layer formed ultrafine grains (UFG) and unrecrystallized block grains with extensive dislocation cells and dislocation walls. Combining the digital image correlation (DIC) technique and in-situ electron backscatter diffraction (EBSD), it was found that the microstructural heterogeneities induced significant strain gradients near the layer interface during plastic deformation, which needed to be accommodated by geometrically necessary dislocations (GNDs). This resulted in hetero-deformation-induced (HDI) strengthening and HDI strain hardening to strengthen and toughen the AZ31 laminated composite. Additionally, the introduction of the Ti layer effectively hindered the propagation of the cracks and consequently improved the ductility of the laminate.

Optimizing the strength and ductility of pure aluminum laminate via tailoring coarse/ultrafine grain layer thickness ratio

Ultrafine-grained (UFG) materials typically exhibit high strength but disappointingly low ductility due to the limited dislocation accumulation. To evade the strength-ductility tradeoff of UFG pure aluminum (Al), four kinds of UFG/coarse-grained (CG)/UFG sandwich-structured pure Al laminates were designed via extrusion and cold rolling. Microstructure characterization displayed that the grain size of the CG in the four designed laminates always remained ∼5 times that of UFG, indicating significant grain size heterogeneity between the constituent layers. The finite element analysis indicated that as the CG/UFG layer thickness ratio increased, the distribution of residual stress between the constituent layers was inhomogeneous and became more pronounced near the interface, which reduced the tensile ductility of the laminates. Tensile tests indicated that when the CG:UFG layer thickness ratio was 1:3, the laminate obtained a desirable strength and ductility compared to other laminates and UFG sample, with a yield strength of 150 MPa and a tensile ductility of 13.5 %. The optical microscope (OM)-digital image correlation (DIC) results revealed that the significant strain gradient near the layer interface caused by the heterogeneous deformation contributed to hetero-deformation induced (HDI) strengthening and HDI strain hardening, thereby strengthening and toughening the laminate.

Abduction causes increased strain gradient compared to forward flexion: Evidence from a cadaver model of simultaneous strain study of the rotator cuff tendons

BackgroundVarious strain studies of the supraspinatus have been done in isolation. Given that rotator cuff muscles function as a group, it may be physiologically representative to measure strain behaviour with the glenohumeral joint intact. Here, we explored a novel method in measuring simultaneous strain behaviour of the rotator cuff tendons and investigated the effect of full-thickness anterior tear of the supraspinatus on the infraspinatus and subscapularis tendons. MethodsNine cadaveric shoulders were evaluated on a customized rig. Using linear differential variable transducers to measure strain, each shoulder was subjected to up to 60° of elevation in the coronal, scapular, and sagittal planes. We also assessed 30° of external rotation and up to 60° of internal rotation of the humerus. Full-thickness anterior tear of the supraspinatus was then made before re-assessing strain patterns in the scapular plane.Findings:Strain measurements of the intact tendons revealed a significant strain gradient between the articular and bursal sides of the supraspinatus during increasing degrees of elevation in the coronal and scapular planes. Full thickness anterior tear of the supraspinatus is localised to the tendon and does not affect the surrounding cuff musculature, with a potential shielding effect of the infraspinatus during early glenohumeral abduction. InterpretationSignificant strain gradient exists between the articular and bursal sides of the supraspinatus during abduction but not during forward flexion in an intact glenohumeral joint. Rehabilitation exercises for anterior supraspinatus tears can be appropriately targeted on the remaining intact rotator cuff musculature.

A Comparative Study of Pt/Al0.72Sc0.28N/Pt-Based Thin-Film Metal-Ferroelectric-Metal Capacitors on GaN and Si Substrates.

AlxSc1-xN is a nitride-ferroelectric compatible with both CMOS and GaN technology. The origin of ferroelectricity in these ternary nitrides relies on the full inversion of nitrogen atom positions, which is a significantly different structural mechanism than conventional perovskites. Therefore, its ferroelectric characteristics exhibit a high remanent polarization and a tunable coercive field but suffer heavily from leakage currents during the switching event. In this article, we studied epitaxially grown Al0.72Sc0.28N thin films on epitaxial Pt electrode layers deposited on GaN/Al2O3 substrates. The results are compared both structurally and electrically with similar systems on SiO2/Si substrates. Our X-ray diffraction analysis showed that Al0.72Sc0.28N/epi-Pt/GaN is always a complete epitaxial stack without any significant strain gradient. Electrically, this system has an overall lower leakage current and coercive field compared to directly grown, highly crystalline, strained epitaxial Al0.72Sc0.28N/GaN, despite having a lower crystalline quality of the ferroelectric layer. In addition, decreasing the epi-Pt thickness from 100 to 10 nm resulted in further improvement of the leakage profile, which we attribute to a decrease in surface roughness in the thinner Pt. In contrast, the dominant factor of leakage in a fiber-textured system on Si substrates is the Pt(111) texture. Finally, with the combination of in-plane X-ray diffraction and high-resolution scanning transmission electron microscopy, we have demonstrated an all-epitaxial 20 nm Al0.72Sc0.28N/Pt/GaN MFM stack with a sharp interface thickness of less than 1 nm.

Strengthening mechanisms of a heterostructured pure aluminum with extraordinary mechanical properties

To achieve superior mechanical properties in metallic materials, one promising way is to make them into heterogeneous structures (HS). In this work, a novel HS including grain size and dislocation density is developed in commercial pure aluminum through cold-rolling and subsequent partial annealing processes. Tensile tests show that the HS specimen, annealed at 150 °C for 2 min with ~31.1% recrystallized grains, have a high yield strength of ~121 MPa and a good uniform elongation of ~8.5%. The yield strength increases by 10% and the ductility increases by 7 times compared with the as-rolled specimen, respectively. Detailed microstructure characterizations confirm that a significant strain gradient was generated near the interface between the hard zone and soft zone, in which the slip and plugging of geometrically necessary dislocations act as an important role in the abnormal hardening and strengthening phenomena of the HS specimen. To quantify the specific contribution of each strengthening mechanism, we compare the experimental measurements with the theoretical calculations and confirm that the multiple deformation modes are activated by the deformation stress. The hetero-deformation-induced hardening and strengthening effects are responsible for the superior mechanical properties of the heterostructured pure aluminum.

Enhanced strength and ductility of the low-carbon steel with heterogeneous lamellar dual-phase structure produced by cyclic intercritical rolling

Steels with outstanding mechanical properties are desired in industrial applications. Martensitic structure significantly increases the strength in low-carbon steels, but usually sacrifices their ductility. In order to improve the combination of strength and ductility, a full martensitic steel was further processed by cyclic intercritical rolling to produce a novel heterogeneous lamellar structured dual-phase (HLSDP) structure. This processing route constructs a small amount of lamellar ferrite surrounded by high volume fraction of refined martensite, which is a promising heterostructure for hetero-deformation induced (HDI) hardening. The HLSDP steel shows a simultaneously improved strength and ductility (ultimate tensile strength, UTS: 1.85 GPa; uniform elongation, UE: 5.6%), comparing to the lath martensite steel (UTS: 1.68 GPa and UE: 4.1%). The superior tensile properties of HLSDP steel are attributed to the higher strain hardening ability, which is related to the significant HDI hardening. Due to the deformation incompatibility between the soft zone (ferrite) and hard zone (martensite), strain partitioning is occurred during plastic deformation. In addition, micro digital image correlation (μ-DIC) analysis reveals the evolution of strain field during deformation. A significant strain gradient is produced near the interface of ferrite and martensite in the HLSDP steel.

Design of pure aluminum laminates with heterostructures for extraordinary strength-ductility synergy

• Pure aluminum laminates with various heterostructures were engineered via extrusion, rolling and annealing. • The designed laminates exhibited an excellent strength-ductility synergy. • The evolution of GNDs was observed using in-situ tension. • The strain gradient across the hetero-interface was revealed using DIC technique. • Hetero-deformation induced (HDI) strengthening and hardening contributed to the superior mechanical properties. Heterogeneous metals and alloys are a new class of materials with superior mechanical properties. In this paper, we engineered sandwich-structured pure aluminum laminates composed of middle coarse-grained layer and outer fine-grained layer via extrusion, rolling and annealing. By controlling the post-annealing regimes, a larger degree of microstructure heterogeneities such as boundary spacing, misorientation and texture across the hetero-interface were obtained, which resulted in obvious mechanical differences. Tensile tests indicated that the 300 °C/30 min annealed laminates enabled a relatively high tensile ductility while simultaneously retaining a high strength, which was better than prediction by the rule-of-mixture. To explain the reasons behind it, the evolution of geometrically necessary dislocations and strain gradient at the hetero-interface zone were detected using in-situ tension and microscopic digital image correlation technique. It was found that with the increasing applied strain, a significant strain gradient was developed near the interface, which was accommodated by geometrically necessary dislocations, thereby contributing to higher hetero-deformation induced (HDI) strengthening and hardening.

Structural characterization and nanoscale strain field analysis of α/β interface layer of a near α titanium alloy

Abstract In this article, the structural and nanoscale strain field of the α/β phase interface layer in Ti80 alloy were studied by using high-resolution transmission electron microscopy (HRTEM) and geometric phase analysis (GPA). The α/β interface layer was observed in forged and different annealed Ti80 alloys, which is mainly composed of lamellar face-centered cubic (FCC) phase region and α′ + β region. The FCC phases between α and β phases show a twin relationship, and the twinning plane is ( 1 1 ¯ 1 ) (1\bar{1}1) . The orientation relationship of the β phase, the α phase, and the FCC phase is (110)β//(0001)α// ( 1 1 ¯ 1 ) (1\bar{1}1) FCC and [ 1 ¯ 11 \bar{1}11 ]β//[ 2 1 ¯ 1 ¯ 0 2\bar{1}\bar{1}0 ]α//[011]FCC. The nanoscale strain field of FCC + α and β + α′ regions was analyzed by using the GPA technology. The FCC + α region shows more significant strain gradient than the α′ + β region, and ε FCC > ε α, ε α′ > ε β. The influence of element addition on the formation mechanism of the FCC phase was discussed. The addition of Zr promotes the formation of the FCC phase by inducing lattice distortion and reducing the stacking fault energy of the α phase. In addition, the Al element forms an obvious concentration gradient around the interface layer during the cooling process of the alloy, which provides a driving force for the formation of the FCC phase.

Structural evolution during nanostructuring of additive manufactured 316L stainless steel by high-pressure torsion

This study investigates the structural evolution including crystallite size, micro-strain, and lattice parameters of an additive manufactured 316L stainless steel during post-printing nanostructuring by high-pressure torsion (HPT) at room temperature. Formation of a martensite phase was observed in the nanostructured austenitic steel having an average grain size of 60 nm after 8 HPT turns. Significant strain gradients exist between the close-packed planes and out-of-close-packed-planes in the nanocrystalline structure, while such strain gradient was not observed in the as-built material. Structural changes occur in a very early stage of nanostructuring through 1/2 HPT turn and are attributed to severe lattice distortion by the excess of dislocations and defects.

Size effect on void coalescence under intense shear

Void interaction, leading to coalescence, is the mechanism leading to ductile failure under intense shearing. Published unit cell model studies have demonstrated that micron-size voids collapse to form micro-cracks while continuous elongation and rotation of the voids thin the intervoid ligaments. At a final stage, the deformation leads to plastic flow localization in the ligament, and the material loses the load-carrying capacity. The micro-mechanism of void collapse, elongation, and rotation has been studied using 2D and 3D unit cell simulations but only within a conventional strain hardening material and, thereby, not accounting for micron scale size effects. However, the severe plastic deformation near the voids implies the development of significant plastic strain gradients, which must be accommodated by geometrically necessary dislocations (GNDs) that strengthens the matrix locally and elevates the stress level. The present research accounts for such gradient strengthening within the matrix in order to investigate the material size effect in ductile shear failure. The work presented leans on the unit cell model approach by Tvergaard (2009), but enables a constitutive length parameter to enter the analysis by substituting the matrix with a Fleck–Willis gradient enhanced material. The results reflect the combined effect of applied load, strain hardening, initial void volume fraction, and microstructure size. The general conclusion is that matrix strengthening, governed by size, delays the loss of load-carrying capacity and leads to less concentrated localization around small void. The results also show that the void collapse, elongation, and rotation mechanism is more sensitive to changes to the applied load, hardening, and initial void volume fraction at small scales.

Late Miocene constrictional strain in the northern Apennines: A case study from the Barabarca metaconglomerate (Elba Island, Italy)

Finite strain analyses were performed on a deformed metaconglomerate from the Calamita Unit in the Island of Elba. The Calamita Unit is a synkinematic contact aureole that was shaped by Late Miocene contractional deformation coeval with high‐temperature metamorphism. The metaconglomerate occurs as an L‐tectonite in the footwall of a major thrust, entirely surrounded by S‐tectonites developed in schistose rocks. Object lineations, defined by the preferred orientation of clasts, trend subparallel to the stretching lineations in the associated rocks. Quartz microstructures registered ductile deformation of clasts by grain boundary migration to bulging recrystallization, suggesting temperature decrease during deformation. Rf/ϕ analyses were carried out on three metaconglomerate samples using quartzite clasts as markers. The finite strain data show that the metaconglomerates are strongly deformed in the constrictional field with K values between ~3 and ~7. The constrictional deformation registered by the metaconglomerate with respect to the surrounding metapelites, which likely deformed under plane strain, can be interpreted as the result of flow partitioning in rheologically heterogeneous sequences during deformation. These results suggest the presence of significant strain gradients in the Calamita Unit, strictly associated with heterogeneously distributed ductile shear zones.

Revealing extra strengthening and strain hardening in heterogeneous two-phase nanostructures

Heterogeneous metals and alloys are a new class of materials that emerged recently with outstanding mechanical performances such as excellent strength-ductility synergy, significant friction and wear reduction and high fatigue limits. Experiments demonstrated that back stress plays an important role in enhancing the strength-ductility balance. However, how does the back stress play the role remains fully unsolved. Here for a two-phase heterogeneous nanostructured Cu we proposed that the strong strain partitioning between the phases with high mechanical contrast due to the large variation of their grain sizes produces significant strain gradient and geometrically necessary dislocations (GNDs). The piling up of the GNDs at the phase interface generates high back stress towards the dislocation source in order to emit new dislocations. The above physical picture is incorporated into a newly developed theoretical model, in which the mechanical responses of the constituent phases with various grain sizes are described by a dislocation density based model, while the overall response is obtained by a secant method for an inclusion-matrix composite. The results show that the soft phase is considerably strengthened. The strain hardening capability of the heterogeneous composite is also enhanced to a large extent, even much higher than that the coarse-grained Cu. The strong strain hardening capability makes the heterogeneous Cu overcome the strength-ductility tradeoff that is usually the case of the homogeneous counterparts. The predicted stress-strain response agrees well with the existing experimental data. A strength-ductility map is also given for designing strong and ductile heterogeneous Cu by selecting smaller grain size in the hard phase, larger grain size in the soft phase and less soft materials. The developed model can be easily extended to investigate the strengthening and strain hardening behavior of other heterogeneous nanostructures such as gradient, laminate, nanotube strengthened and metallic glass/metallic substrate structures.

Coordination-dependent surface strain and rational construction of robust structures

A surface relaxation model is established to study the elastic properties of nanoscale structures. This model predicts coordination-dependent strain at the surface and thickness-dependent stiffness of a material. Several atomic layers at the surface endure a significant strain gradient, which is dominated by the intrinsic properties of the material. The stiffness of low-dimensional materials is enhanced by surface relaxation effect. Surface effects on strong structures, including honeycomb structure and octet-truss structure with a high stiffness-to-weight ratio, are discussed. For these structures assembled with nanobeams, the Young’s modulus decreases with decreasing size of the struts. The coupling between Young’s modulus and relative density can be scaled down by engineering tensile strain on the struts.

Present-day crustal deformation characteristics of the southeastern Tibetan Plateau and surrounding areas by using GPS analysis

The southeastern Tibetan Plateau and surrounding areas comprise a typical tectonic belt in mainland China, characterized by a complex geological background and intense tectonic activity. We study present-day crustal deformation characteristics of this region based on GPS data for the periods 1999–2007 and 2009–2011. We first analyze the variations in crustal motion and strain rate, and then discuss the 3D crustal motion and local sub-block activities, as well as the correlation between the intensity of crustal activity and the strain rate distribution. Finally, we explain the present-day geodynamic characteristics of the region. Our results indicate that the entire region shows overall clockwise motion with respect to the stable Eurasian Plate. The tectonic boundary belts between this region and the South China Block display significant compressional strain, accompanied by associated extensional strain. Relatively high maximum shear strain and the transition zones of the significant plane strain gradients are also mainly concentrated along the Ganzi–Yushu–Xianshuihe, Anninghe–Zemuhe–Xiaojiang, Lijiang–Xiaojinhe, and Red River faults, as well as the western and southern Yunnan Province. 3D crustal velocities further reflect significant differences in tectonic activity between different structural belts. We conclude that the regions showing higher shear strain and the transition zones of the significant plane strain gradients correspond to the areas with frequent earthquakes. According to the crustal deformation and strain characteristics, we infer that the present-day geodynamic setting of the region is related to the ongoing India–Eurasia collision and the associated resistance of the stable Alashan, Ordos, and South China blocks, resulting in the extrusion of the southeastern Tibetan Plateau crustal material with an overall clockwise flow around the Eastern Himalayas and significant compressional strain along the tectonic boundary belts. Furthermore, notable compressional strain and enhanced sub-block motions occurred around the Longmenshan fault area following the Wenchuan earthquake.