Kinematics Of Deformation Research Articles

Surface Velocities and Strain-Rates in the Euro-Mediterranean Region From Massive GPS Data Processing

In this work we present and discuss new geodetic velocity and strain-rate fields for the Euro-Mediterranean region obtained from the analysis of continuous GNSS stations. We describe the procedures and methods adopted to analyze raw GPS observations from >4000 stations operating in the Euro-Mediterranean, Eurasian and African regions. The goal of this massive analysis is the monitoring of Earth’s crust deformation in response to tectonic processes, including plate- and micro-plate kinematics, geodynamics, active tectonics, earthquake-cycle, but also the study of a wide range of geophysical processes, natural and anthropogenic subsidence, sea-level changes, and hydrology. We describe the computational infrastructure, the methods and procedures adopted to obtain a three-dimensional GPS velocity field, which is used to obtain spatial velocity gradients and horizontal strain-rates. We then focus on the Euro-Mediterranean region, where we discuss the horizontal and vertical velocities, and spatial velocity gradients, obtained from stations that have time-series lengths longer than 6 and 7 years, which are found to be the minimum spans to provide stable and reliable velocity estimates in the horizontal and vertical components, respectively. We compute the horizontal strain-rate field and discuss deformation patterns and kinematics along the major seismogenic belts of the Nubia-Eurasia plate boundary zone in the Mediterranean region. The distribution and density of continuous GNSS stations in our geodetic solution allow us to estimate the strain-rate field at a spatial scale of ∼27 km over a large part of southern Europe, with the exclusion of the Dinaric mountains and Balkans.

Influence of foundation stiffness on deformation of layered building structures

Widespread introduction into the industry of layered structures, in particular three-layer plates, shells and is impossible without effective methods of their strength and reliability. High strength and rigidity at relatively low weight damping and thermal insulation properties of these structures have led to their use in modern construction and mechanical engineering. Three-layer plates and shells, as a rule, are a combination of materials heterogeneous in their physical and mechanical properties. The calculation of such structures is a very complex task, the solution of which should be based on mathematical models with a high degree of reliability and reflect the real mechanical properties. During operation, three-layer structures are under the influence of significant static loads. Therefore, the development of effective and cost-effective methods for solving the problems of statics of three-layer systems is an urgent problem. In transport construction, the calculation scheme in the form of a plate on an elastic basis is used to calculate pavement, slabs. The paper considers the bending of a three-layer plate with a rigid filler, which is on an elastic basis. Hypotheses of a broken line are accepted for the description of kinematics of deformation. The contour of the plate has a rigid diaphragm, which prevents the relative displacement of the layers. Analytical and numerical calculations of the three-layer finite element method were performed. As a result of the calculation, the dependences of the deflection on the stiffness coefficient of the base were determined. Recommendations on the choice of stiffness factor are given. Taking into account the stiffness of the elastic base leads to a significant clarification of the stress state that occurs in the three-layer plate under external force. The influence of the stiffness of the base on the deflection of the structure is analyzed, it gives the opportunity to determine the optimal parameters of this mechanical system, and give the necessary recommendations for its use.

Analytical, numerical and experimental study of the finite inflation of circular membranes

In the present work we derive an analytical expression for the pressure–deflection curve of circular membranes subjected to inflation. This problem has been studied mostly from a numerical point of view and there is still a lack of accurate closed-form solutions in nonlinear elasticity. The analytical formulation is developed with a semi-inverse method by setting a priori the kinematics of deformation of the membrane. A compressible Mooney–Rivlin material model is considered and a pressure–deflection relation is derived from the equilibrium. The kinematics is approximated and therefore the obtained solution is not exact. Consequently, the formulation is adjusted by introducing an additional polynomial function in the pressure–deflection equation. The polynomial is calibrated by fitting numerical solutions of the exact system of differential equilibrium equations. The calibration is done over a wide range of constitutive parameters that covers the response of all rubber materials for technological applications. As a result, a definitive and accurate expression of the applied pressure as a function of the deflection of the membrane is obtained. The formula is validated with finite element (FE) simulations and compared with other solutions available in the literature. The comparison shows that the present model is more accurate. In addition, unlike the other models, it can be applied to compressible materials. Experimental uniaxial and bulge tests are carried out on rubber materials and the model proposed is used to characterize the Mooney–Rivlin constitutive parameters. Since the pressure–deflection formula is accurate and easy-to-use, it is an innovative tool in engineering applications of inflated membranes.

QUaternary fault strain INdicators database - QUIN 1.0 - first release from the Apennines of central Italy

We present QUIN, a “QUaternary fault strain INdicators database”, designed to integrate and unify published and unpublished local-scale geological information and derive strain parameters for structural and seismotectonic analyses. It provides data on 3339 Fault Striation Pairs (FSP; fault plane and slickenline), distributed within 455 survey sites. These are exposed along the intra-Apennine Quaternary extensional faults of Central Italy. The area covers an extent of ~550 km in a NW-SE direction. We give information on FSP location, attitude and kinematics, and deformation axes. We also provide an original shapefile of the faults hosting the FSP. A large amount of homogeneously distributed Quaternary fault/slip data help to clarify and implement the contemporary geometric and kinematic deformation pattern of Central Italy that appears scattered and incomplete whenever exclusively derived from earthquake data. The high-density of structural data can help investigate stress pattern heterogeneities at local scales, with relevance for new generations of hazard assessment evaluation and a better understanding of rupture propagation and related barriers.

Progressive Development of a Distributed Ductile Shear Zone beneath the Patagonian Retroarc Fold-Thrust Belt, Chile

Abstract The southern Patagonian Andes record Late Cretaceous–Paleogene compressional inversion of the Rocas Verdes backarc basin (RVB) and development of the Patagonian fold-thrust belt (FTB). A ductile décollement formed in the middle crust and accommodated underthrusting, thickening, and tectonic burial of the continental margin (Cordillera Darwin Metamorphic Complex (CDMC)) beneath the RVB. We present new geologic mapping, quartz microstructure, and crystallographic preferred orientation (CPO) fabric analyses to document the kinematic evolution and deformation conditions of the décollement. Within the CDMC, the décollement is defined by a quartz/chlorite composite schistose foliation (S1-2) that is progressively refolded by two generations of noncylindrical, tight, and isoclinal folds (F3–F4). Strain intensifies near the top of the CDMC, forming a >5 km thick shear zone that is defined by a penetrative L-S tectonite (S2/L2) and progressive noncylindrical folding (F3). Younger kink folds and steeply inclined tight folds (F4) with both north- and south-­dipping axial planes (S4) overprint D2 and D3 structures. Quartz textures from D2 fabrics show subgrain rotation and grain boundary migration recrystallization equivalent to regime 3, and quartz CPO patterns indicate mixed prism <a> and [c] slip systems with c-axis opening angles indicative of deformation temperatures between ~500° and >650°C. Approximately 40 km toward the foreland, the shear zone thins (~1 km thick) and is defined by the L-S tectonite (S2/L2) and tightening of recumbent isoclinal folds (F3). Quartz textures and CPO patterns indicate subgrain rotation recrystallization typical of regime 2 and dominantly basal <a> slip, and c-axis opening angles are consistent with deformation temperatures between ~375° and 575°C. Deformation occurred under greenschist and amphibolite facies conditions in the foreland and hinterland, respectively, indicating that the shear zone dipped shallowly toward the hinterland. The Magallanes décollement is an example of a regional ductile shear zone that accommodated distributed middle to lower crustal thickening below a retroarc FTB.

Stability analysis of three-dimensional thick rectangular plate using direct variational energy method

This study investigated the elastic static stability analysis of homogeneous and isotropic thick rectangular plates with twelve boundary conditions and carrying uniformly distributed uniaxial compressive load using the direct variational method. In the analysis, a thick plate energy expression was developed from the three-dimensional (3-D) constitutive relations and kinematic deformation; thereafter the compatibility equations used to resolve the rotations and deflection relationship were obtained. Likewise, the governing equations were derived by minimizing the equation for the potential energy with respect to deflection. The governing equation is solved to obtain an exact deflection function which is produced by the trigonometric and polynomial displacement shape function. The degree of rotation was obtained from the equation of compatibility which when equated to the deflection function and put into the potential energy equation formulas for the analysis were obtained after differentiating the outcome with respect to the deflection coefficients. The result obtained shows that the non-dimensional values of critical buckling load decrease as the length-width ratio increases (square plate being the highest value), this continues until failure occurs. This implies that an increase in plate width increases the probability of failure in a plate. Hence, it can be deduced that as the in-plane load on the plate increase and approaches the critical buckling, the failure in a plate structure is abound to occur. Meanwhile, the values of critical buckling load increase as the span-thickness ratio increases for all aspect ratios. This means that, as the span-thickness ratio increases an increase in the thickness increases the safety in the plate. It also indicates that the capacity of the plate to resist buckling decreases as the span-depth ratio increases. To establish the credibility of the present study, classical plate theory (CPT), refined plate theory (RPT) and exact solution models from different studies were employed to validate the results. The present works critical buckling load varied with those of CPT and RPT with 7.70% signifying the coarseness of the classical and refined plate theories. This amount of difference cannot be overlooked. The average total percentage differences between the exact 3-D study (Moslemi et al., 2016), and the present model using polynomial and trigonometric displacement functions is less than 1.0%. These differences being so small and negligible indicates that the present model using trigonometric and polynomial produces an exact solution. Thus, confirming the efficacy and reliability of the model for the 3-D stability analysis of rectangular plates.

A new interpretation of the metamorphic core in the Taiwan orogen: A regional-scale, left-lateral shear zone that accommodated highly oblique plate convergence in the Plio-Pleistocene

In the past decades, the arc-continent collision in Taiwan was commonly interpreted as a relatively continuous process with an invariant plate convergence vector for at least the last 6–5 Ma. This steady convergence, including the rate and the obliquity, between the subducting continental margin and the plate boundary suggest a propagating collision with a space-time equivalence along the developing orogen. More recently, detailed low-temperature geochronologic and plate reconstructions suggest that the plate convergence changed from highly oblique to nearly orthogonal in the last 2 to 1 Ma. This early phase of oblique convergence, driven primarily by the northward motion of the Philippine Sea Plate wrt the Eurasian Plate, implies a significant ‘fossil’ component of left-lateral, strike-slip motion along the presumably north-trending plate boundary. A synthesis of available data compiled in this study suggests that previously uncharacterized zones of strike-slip deformation exist in the Tailuko Belt, and here we document: 1) the distribution of horizontal shear, 2) the kinematics of deformation, 3) the age of deformation, and 4) regional consistency between geologic studies and plate reconstructions. Horizontal shear may also be recorded at shallow structural levels in southern Taiwan by brittle faults and block rotations. Integration of these new data with previously published kinematic data across strike also suggests plate convergence was partitioned with strike-slip motion in the retrowedge (i.e., the Tailuko Belt) and shortening in the prowedge (i.e., the Slate Belt).

Strain Distribution Along the Qilian Fold-and-Thrust Belt Determined From GPS Velocity Decomposition and Cluster Analysis: Implications for Regional Tectonics and Deformation Kinematics

The Qilian fold-and-thrust belt (QFTB) offers an excellent example to demonstrate the strain transition from strike–slip shearing to oblique crustal shortening, which plays an important role in dissecting the stress propagation of Indian–Eurasian convergence from the plateau interior to the surrounding blocks. Various geological or numerical models have attempted to describe the regional tectonic characteristics of the QFTB. However, these models only interpret one or part of the deformation behaviors in the QFTB, and the strain distribution across and along the QFTB as well as its deformation kinematics remains to be determined. Therefore, in this work, we applied the method of velocity decomposition and cluster analysis using combined GPS data to determine the strain partition or accommodation in different parts of the QFTB as well as tectonic relationships with surrounding blocks, which will contribute to distinguishing which model is more suitable for delineating the present-day deformation kinematics of the QFTB. Our analysis indicates that the western part of the QFTB is dominated mainly by crustal shortening perpendicular to the trend of the QFTB, coupled with lateral extension along the trend of the QFTB, while the eastern part of the QFTB is characterized mainly by lateral extrusion owing to the impact of two large eastward-striking left-slip faults (East Kunlun fault and Haiyuan fault), which are accommodated by an obvious velocity gradient boundary belt centered on two diamond basins (Qinghaihu and Gonghe basins) associated with their boundary faults. The active tectonics of the QFTB are obviously divided into two distinct groups: one group is a pure shear–strain pattern, accounting for strong crustal shortening in the western part of the QFTB, and the other group is a simple shear–strain pattern, accounting for the obvious lateral extrusion in the eastern part of the QFTB.

Controls of mantle subduction on crustal-level architecture of intraplate orogens, insights from sandbox modeling

Subduction of mantle lithosphere can initiate in the continental interior and acts as an important mechanism for intraplate orogeny. However, the associated kinematic response in the upper crust is still poorly resolved, hindering identification and investigation of mantle subduction during intraplate orogeny. Here we conducted sandbox experiments incorporating mantle-subduction-type and traditional indentation-type convergence to explore their difference in crustal-level orogenic architecture and deformation kinematics. We demonstrate that mantle-subduction-type convergence enhances orogen expansion above the subducting plate, whereas indentation-type convergence promotes deformation propagation toward the overriding plate. Such contrast leads to systematic variations in deformation sequence, structural style, and the first-order orogen geometry. We also show that changes of convergence mode leave distinct structural relics. Out-of-sequence faulting occurs when indentation-type convergence replaces the mantle-subduction-type mode. Conversely, the overprinting of mantle subduction on an earlier indentation mode triggers immediate in-sequence, foreland-propagating thrusting. Additionally, the influence of mantle-subduction-type convergence concentrates within the subducting plate when under a combined convergence involving opposite-direction indentation and mantle-subduction. This creates a special pattern of deformation localization comparable to the distribution of present-day seismicity and topography observed in the active Qilian Shan fold-thrust (northern Tibetan Plateau), confirming a bi-directional compression state during its recent evolution. Our modeling results can provide insights into the geodynamics of other intraplate orogens.

An analytical model for flexural vibration of composite beams with shear slip based on third order deformation kinematics

In this paper, an analytical solution is derived for accurately predicting the free and forced vibration responses due to time varying as well as moving loads of two layered composite beams which consist of two different materials. For this purpose, the third order deformation kinematics is used in the proposed model, and it allows to take a parabolic (third order) variation of the longitudinal displacement along the beam depth for the two material layers. The partial shear interaction between the two material layers produced by the deformability of shear connectors joining these layers in the form of shear slip at their interface is modelled using distributed shear springs along the beam length. Hamilton’s principle is applied to derive the governing equations of the dynamic system which are solved analytically using a Navier type solution technique. Moreover, a two-dimensional (2D) finite element model is built up in ABAQUS for the validation of the proposed analytical model. Some parametric studies are conducted to investigate the effect of shear deformation on the forced vibration response of a two-layered composite beam partial with different shear stiffness, span-to-depth ratio and elastic-to-shear modulus ratio.

Late Cenozoic Extensional Formation of the Antofalla Depression, Southern Puna Plateau, Argentina: An Effect of Lithospheric Foundering?

AbstractDeformation within orogenic plateaus functions to establish a dynamic equilibrium between tectonic boundary stresses and plateau gravitational potential energy. Temporal changes in deformation kinematics record perturbations to boundary stresses or internal plateau processes, such as lithospheric foundering. We integrate new mapping, field observations, and geochronologic ages with published data to document complex late Cenozoic upper crustal deformation in the region of the Antofalla depression, a ∼125 km long, sublinear basin within the southern Puna orogenic plateau, Argentina. The juxtaposition of stratal ages across the depression requires >900 m vertical offset on a surface‐breaking fault. Regional geologic structure, basin geomorphology, and our observation of a breccia paralleling the depression margin suggest formation of the depression by normal faulting. We interpret published stratigraphic logs to suggest that the depression formed between ca. 16 and 11 Ma following Andean shortening. Folded Late Miocene to Quaternary strata on the eastern depression margin indicate that extension ended and shortening resumed before present, revealing toggling between extensional and contractional kinematic regimes. The kinematic evolution of the Antofalla depression contrasts with the rest of the southern Puna plateau, which underwent shortening until latest Miocene to Quaternary time, followed by extension and strike‐slip deformation. Taken together, the spatial and temporal variations in late Cenozoic deformation of the southern Puna plateau are inconsistent with mechanisms that would affect the entire orogen, such as slowing convergence, but are compatible with lithospheric foundering.

Light-Induced Topological Patterning toward 3D Shape-Reconfigurable Origami.

Shape-reconfigurable materials are crucial in many engineering applications. However, because of their isotropic deformability, they often require complex molding equipment for shaping. A polymeric origami structure that follows predetermined deformed and non-deformed patterns at specific temperatures without molding is demonstrated. It is constructed with a heterogeneous (dynamic and static) network topology via light-induced programming. The corresponding spatio-selective thermal plasticity creates varied deformability within a single polymer. The kinematics of site-specific deformation allows guided origami deployment in response to external forces. Moreover, the self-locking origami can fix its geometry in specific states without pressurization. These features enable the development of shape-reconfigurable structures that undergo on-demand geometry changes without requiring bulky or heavy equipment. The concept enriches polymer origamis, and could be applied with other polymers having similar chemistries. Overall, it is a versatile material for artificial muscles, origami robotics, and non-volatile mechanical memory devices.

Effect of microstructure on the dynamic behavior of Ultra-High-Molecular-Weight Polyethylene (UHMWPE) composites

We study the effects of composite microstructure on the dynamic response of Ultra-High Molecular Weight Polyethylene (UHMWPE) fiber-reinforced composites when loaded in out-of-plane compression. Using a Kolsky bar, we dynamically load the composites (of differing microstructures) in out-of-plane compression while simultaneously capturing the deformation history with high speed video with μs temporal resolution and approximately 10μm spatial resolution. Image analysis is performed on the resulting high speed video to obtain the finite deformation kinematics of the specimen, including the dynamic lateral deformations, and obtain the complete deformation gradient history during the tests. Using a finite deformation formulation, we measure the evolution of the volumetric deformations and relate this to porosity evolution within the specimen. Specimens are also tested at quasistatic strain rates and their response is compared in the range of strain-rates from 10−3s−1 to 3000s−1. These materials are quite compressible, and their volume can change very rapidly during out-of-plane compression. The volume change is accommodated by a reduction in porosity at low to moderate strains. In the uniaxial stress samples, high strains lead to volume change by ejection of material, and the evolution of material ejection is rate dependent. In both microstructures, deformation at the higher strain rate led to material ejection being initiated at higher stress, ejection evolving more slowly as a function of applied stress, and developing a plateau at a lower stress (than in the quasistatic case). At quasistatic strain-rates, there was little difference between the response of the two microstructures; however at high strain rates of 103s−1, the microstructure with lower porosity displayed a higher strength. The rate sensitivity of the strength was shown to depend on the microstructure, suggesting the defect distribution plays a significant role in the dynamic strength of these materials.

Nonlinear static and dynamic performance of CNT reinforced and nanoclay modified laminated nanocomposite plate

Under static and dynamic loading circumstances, the mechanically and thermo-initiated nonlinear static and dynamic assessment of the bending response of single-walled carbon nanotubes’ (CNTs’) fibers with a nanoclay particle reinforced polymer hybrid laminated composite plate is investigated. To evaluate the effective elastic characteristics of the CNTs’ fibers on the nanoclay particle modified polymer hybrid laminated plate, a modified Halpin–Tsai method is applied in an orthotropic way. The theory of higher-order shear deformation and complete kinematics (nonlinear) are used to develop the fundamental nonlinear dynamic formulation. A user-interactive finite element method-based MATLAB program solves the governing equations for nonlinear dynamic systems utilizing Newmark’s period integration and the Newton–Raphson method. The effects of variation in the quantity of CNTs’ fibers and particles of nanoclay, presence of interphases around CNTs’ fibers and nanoclay particles, variation in phases of the CNTs’ fibers on the nanoclay particle modified polymer hybrid laminated plate, and variation in plies of the laminated hybrid plate under clamped and simply supported conditions on the transverse central deflection response are explored in depth.

The concept of Representative Crack Elements (RCE) for phase-field fracture: transient thermo-mechanics

The phase-field formulation for fracture based on the framework of representative crack elements is extended to transient thermo-mechanics. The finite element formulation is derived starting from the variational principle of total virtual power. The intention of this manuscript is to demonstrate the potential of the framework for multi-physical fracture models and complex processes inside the crack. The present model at hand allows to predict realistic deformation kinematics and heat fluxes at cracks. At the application of fully coupled, transient thermo-elasticity to a pre-cracked plate, the opened crack yields thermal isolation between both parts of the plate. Inhomogeneous thermal strains result in a curved crack surface, inhomogeneous recontact and finally heat flow through the crack regions in contact. The novel phase-field framework further allows to study processes inside the crack, which is demonstrated by heat radiation between opened crack surfaces. Finally, numerically calculated crack paths at a disc subjected to thermal shock load are compared to experimental results from literature and a curved crack in a three-dimensional application are presented.

Simultaneous Wide-Field Planar Strain-Fiber Orientation Distribution Measurement Using Polarized Spatial Domain Imaging.

In the present study, we demonstrate that soft tissue fiber architectural maps captured using polarized spatial frequency domain imaging (pSFDI) can be utilized as an effective texture source for DIC-based planar surface strain analyses. Experimental planar biaxial mechanical studies were conducted using pericardium as the exemplar tissue, with simultaneous pSFDI measurements taken. From these measurements, the collagen fiber preferred direction [Formula: see text] was determined at the pixel level over the entire strain range using established methods ( https://doi.org/10.1007/s10439-019-02233-0 ). We then utilized these pixel-level [Formula: see text] maps as a texture source to quantify the deformation gradient tensor [Formula: see text] as a function of spatial position [Formula: see text] within the specimen at time t. Results indicted that that the pSFDI approach produced accurate deformation maps, as validated using both physical markers and conventional particle based method derived from the DIC analysis of the same specimens. We then extended the pSFDI technique to extract the fiber orientation distribution [Formula: see text] as a function of [Formula: see text] from the pSFDI intensity signal. This was accomplished by developing a calibration procedure to account for the optical behavior of the constituent fibers for the soft tissue being studied. We then demonstrated that the extracted [Formula: see text] was accurately computed in both the referential (i.e. unloaded) and deformed states. Moreover, we noted that the measured [Formula: see text] agreed well with affine kinematic deformation predictions. We also demonstrated this calibration approach could also be effectively used on electrospun biomaterials, underscoring the general utility of the approach. In a final step, using the ability to simultaneously quantify [Formula: see text] and [Formula: see text], we examined the effect of deformation and collagen structural measurements on the measurement region size. For pericardial tissues, we determined a critical length of [Formula: see text] 8 mm wherein the regional variations sufficiently dissipated. This result has immediate potential in the identification of optimal length scales for meso-scale strain measurement in soft tissues and fibrous biomaterials.

Smart control of functionally graded sandwich plates by incorporating Murakami zig-zag function

This study is aimed at incorporating the zig-zag effect by Murakami zig-zag function in the development of a finite element model for active constraining layer damping treatment of functionally graded sandwich plates. The present sandwich construction consists of functionally graded facings distanced by a ceramic core. The substrate functionally graded plate is subjected to active constraining layer damping treatment, which in itself is a two-layered material system comprised of a viscoelastic layer and a 1–3 piezoelectric composite layer. The deformation kinematics of the functionally graded sandwich plate active constraining layer damping system is shaped using Murakami zig-zag function, and the finite element model is obtained by the virtual work principle. A standard feedback control system has been implemented, and a MATLAB subroutine has been developed to present the open- and closed-loop responses. Substrate plates with functionally graded configurations 1-1-1, 1-2-1, and 2-1-2 are considered to evaluate the effect of active constraining layer damping on damping the frequency responses of these plates. Investigation on damping performance has been carried out, bearing in mind the change in power-law index with top and bottom ceramic-/metal-rich surfaces. Also, the effect of variation in fiber orientation angle (obliquely reinforced) of the piezoelectric composite material on the active constraining layer damping performance has been examined thoroughly.

Spatial-Temporal Kinematics of Material Deformation with In-Situ Dic Method During Orthogonal Cutting Ti6al4v

Spatial-Temporal Kinematics of Material Deformation with In-Situ Dic Method During Orthogonal Cutting Ti6al4v

Dynamic fracture with continuum-kinematics-based peridynamics

<abstract><p>This contribution presents a concept to dynamic fracture with continuum-kinematics-based peridynamics. Continuum-kinematics-based peridynamics is a geometrically exact formulation of peridynamics, which adds surface- or volume-based interactions to the classical peridynamic bonds, thus capturing the finite deformation kinematics correctly. The surfaces and volumes considered for these non-local interactions are constructed using the point families derived from the material points' horizon. For fracture, the classical bond-stretch damage approach is not sufficient in continuum-kinematics-based peridynamics. Therefore it is here extended to the surface- and volume-based interactions by additional failure variables considering the loss of strength in the material points' internal force densities. By numerical examples, it is shown that the presented approach can correctly handle crack growth, impact damage, and spontaneous crack initiation under dynamic loading conditions with large deformations.</p></abstract>

FORMATION OF QUALITATIVE INDICATORS OF PRODUCTS BY ROLLING STAMPING PROCESSES

The influence of rolling stamping on the service characteristics of products is investigated in the work. Based on the analysis of deformation kinematics, stress-strain state, microstructure and evaluation of deformability of workpiece material, ways to increase geometric accuracy, vacuum tightness, electrolytic stability and mechanical characteristics of product material, as well as ways to improve the material of workpieces for their subsequent processing. The influence of active friction forces on the nature of the material flow during SHO was established, which contributed to the development of new processes that allow to bring the shape and dimensions of the workpiece as close as possible to the finished part. Thus accuracy of the sizes of details corresponds to 7-11th qualities of accuracy, and roughness of the processed surfaces makes Ra = 2,5… 0,63 microns. The process of reshaping the square billets into round ones by the method of SHO is effective, which increases the utilization factor of the metal and reduces the anisotropy of its mechanical properties. The characteristic of flat anisotropy λr, adopted in sheet metal stamping as a characteristic of the ability of the material to form scallops, decreases as a result of reshaping by 70-80%. The relative difference in yield strength in the plane of the sheet decreases from 0.10-0.15 to 0.03-0.05. The ultimate tensile strain increases by 8-10%, and the uniform uniform strain - by 5-8%. This improvement in the characteristics of the material reshaped by rolling blanks leads to the fact that when drawing cylindrical products, the value of scallops decreases by 2-2.5 times, and the value of the maximum degree of drawing increases by 10-15%. This reduces the relative difference in wall thickness along the perimeter of the elongated workpiece, and the change in wall thickness along its height becomes linear. Thus, the use of SHO processes significantly improves the quality characteristics of products.