Deformation Analysis Of Structures Research Articles

Continuous structural deformation of graphene oxide liquid crystal colloids under shear for hydrogel films

In the processing of two-dimensional (2D) liquid crystal (LC), the microstructure of 2D LC colloids is continuously deformed by shearing, which ultimately determines their physical properties. However, it is experimentally difficult to investigate and visualize how the microstructure continuously changes during processing involving shear stress. Thus, controlling the microstructure of 2D LCs using shear forces remains a more difficult problem.Herein, we report the in-situ analysis of structural deformation for 2D colloids liquid crystals focused on the reorientation of the liquid crystal (LC) under oscillatory shear. Graphene oxide (GO) was employed as a model system for 2D LC colloids, and polymers were added to control the 2D colloidal interactions. We found that the GO structure deforms in two steps: The first step is the transition to multi-domains of GO LC and the second transition brings the macroscopic alignment of GO. We additionally found that the added polymer causes the earlier disappearance of multiple GO LC domains and provides a better macroscopic alignment at the same shear condition. The study will be of great interest in the 2D colloidal process accompanying yielding behavior, providing an effective strategy to control the domain orientation and the resulting properties.

Large deformation analysis of shell-type structures using the VDQ-transformed scheme: A two-point formulation based on 3D elasticity

Shell-type structures are frequently used in aerospace, marine and civil engineering. In this paper, a numerical approach called as VDQ-transformed is introduced to analyze the large deformations of hyperelastic shell-type structures based on the Saint Venant–Kirchhoff constitutive model in the context of three-dimensional (3D) nonlinear elasticity. According to the Euler–Lagrange description, the kinetic first Piola-Kirchhoff tensor and kinematic deformation gradient tensor are considered for the stress and strain measures in the formulation. By replacing the tensor form of formulations with matricized ones, the governing equations are written in a novel vector-matrix format which can be readily exploited for programming in numerical approaches. Moreover, discretizing is carried out by the variational differential quadrature (VDQ) method as a point-wise numerical method. To apply the VDQ technique, a transformation is used to map the irregular domain into the regular one. Some well-known benchmark problems for the large deformations of shells are solved to assess the approach. Compact matricized formulation, simple implementation, being locking-free, computational efficiency and fast convergence rate can be mentioned as the main features of the introduced numerical approach.

TLS and FEM combined methods for deformation analysis of tunnel structures

With the increasing of tunnel mileage, one of the most vital problems of broad-scale structures is the intelligent identification and location of structural defects, which require massive data storage capacity and high data processing efficiency. The full-field point cloud data collected by terrestrial laser scanning (TLS) can be extracted to construct three-dimensional measured models more accurately, therefore, the fusion of TLS and the finite element method (FEM) is particularly beneficial to the deformation analysis of tunnel structures. This paper combines numerical simulation and full-field measurement to interactively verify the reliability of deformation analysis based on FEM simulation and point cloud processing. The innovation of this paper is that a three-dimensional FEM is validated through the measured point cloud data of the tunnel structure. The result of this study indicated that FEM simulation and the structural health monitoring analysis are consistent.

On finite deformation of hyperelastic shell-type structures: Cartesian formulation-based VDQ approach

In this article, a numerical approach is presented for the large deformation analysis of shell-type structures made of Neo-Hookean and Kirchhoff–St Venant materials within the framework of the seven-parameter shell theory. Work conjugate pair of the second Piola–Kirchhoff stress and Green–Lagrange strain tensors are taken for the macroscopic stress and strain measures in this total Lagrangian formulation. By defining displacement vector, deformation gradient and stress tensor in the Cartesian coordinate system, and using the chain rule for taking derivative of tensors, the complications of using the curvilinear coordinate system are bypassed. The variational differential quadrature (VDQ) technique as an effective numerical solution method is applied to obtain the weak form of governing equations. Being locking-free, simple implementation, computational efficiency and fast convergence rate are the main features of the proposed numerical approach. A number of well-known benchmark problems are solved in order to reveal the accuracy and efficiency of the method. It is shown that this approach is able to predict the large deformations of hyperelastic shell-type structures in an efficient way.

A novel framework for modeling floating offshore wind turbines based on the vector form intrinsic finite element (VFIFE) method

Currently, there is a rapid demand for the development of floating offshore wind turbines (FOWTs) for deployment in sites with deep water depths. FOWTs are highly complex structures that are subjected to combined loading from wind, hydrodynamic, hydrostatic, and mooring loads, and these loads have a significant influence on their dynamic behavior. The complexity of such a multi-body system makes the dynamic analysis considerably challenging and demands an efficient model to capture the physical characteristics of the system accurately. This paper proposes a novel framework for modeling floating offshore wind turbines (FOWTs) based on the vector form intrinsic finite element (VFIFE) method. In this framework, the multi-body dynamics (MBD) is used to handle the rigid body motion, and the analysis of structural deformation and the solution of governing equation of motions (EOMs) is implemented based on the VFIFE method. The methodology considers the FOWT as two rigid bodies: (a) the tower, which is a structural assembly of platform and nacelle; and (b) the rotor that can mechanically rotate relative to the nacelle. Further, a dynamic and flexible model of the mooring system is included, and their axial extension, inertia, and hydrodynamic loads are considered. The EOMs of the FOWT and mooring system are derived by the Newton-Euler (NE) and Newton's second law, respectively and the central difference scheme is implemented to solve the EOMs. Finally, the developed model is subjected to different load cases under the combined action of wind and waves, and the responses of platform motion and the axial tension of the mooring system are calculated and verified against the FAST. After thorough verification of the VFIFE model which showed excellent agreement with FAST results, the proposed model is used (a) to highlight the variations caused by neglecting the dynamic of the mooring system where the results are compared with the quasi-static mooring model developed using the MAP++ module in FAST, and (b) reveal the coupled mechanism of the platform pitch and yaw motion when the rotor is spinning.

Seismic and failure behavior simulation for RC shear walls under cyclic loading based on vector form intrinsic finite element

Seismic performance and failure mode simulations for reinforced concrete (RC) structures are impeded by large deformations and material nonlinearity particularly when subjected to the combined action of compression, bending and shear. Structural deformation and failure analysis based on traditional finite element (FE) often fails for the small–deformation assumption and global equilibrium. Moreover, it remains difficult to obtain convergence results for the existing FE methods by applying general concrete constitutive models for the complicity of anisotropic materials. To simulate the hysteretic performance and the damage development process of the RC shear wall under cyclic loading, the vector form intrinsic finite element (VFIFE) method with independent particles was adopted and combined with the two-directional concrete constitutive model considering the loading and unloading rules to perform large deformation and damage estimations. Concrete planar triangular element and fiber element for steel bar equipped with the hysteretic constitutive models were used to model six RC shear walls with different design parameters. Owing to the merits of avoiding repeated accumulation of the global stiffness matrix for vector mechanics, the planar structural behaviors involving biaxial stress–strain and loading–unloading behavior were numerically demonstrated. The simulated results were in close agreement with the experimental tests, including the hysteretic loop, skeleton curve, bending–shear deformation, and damage mode. This research also provides successive evidence for damage process simulation by VFIFE for RC structures under seismic loading considering a comprehensive constitutive relation.

Prediction of In-plane Stiffness for the Cold-formed Steel Frame of the Wall Panel Structure

The purpose of this research was to study the lateral deformation behavior of cold-formed steel wall panel structures using experimental tests, finite element analysis and analytical methods to study the lateral stiffness of these structures. The wall panel structures were tested by full-scale experiments the experimental results of which were verified by a 3D-finite element model. The verification results showed a good correlation between the experimental tests and a finite element model. The single-column spring model was proposed for an elastic lateral stiffness analysis of the cold-formed steel wall panel structures that were formed by combinations of a guide cantilever beam and springs connection. The spring constants were defined by using the stiffness of the stub-chord connection and the bending stiffness of the chord. The experiments tests and finite element analysis were used to verify this single-column spring model. The comparison results showed good agreement between the analytical prediction, finite element analysis and experimental data in the case of the primary type of cold-formed wall structure. The proposed procedure was an efficient method for elastic lateral deformation analysis of cold-formed wall panel structures which can be used for such configurations.

Research on Structural Deformation Monitoring and Analysis of Ancient Castle Buildings Using Three-Dimensional Laser Scanning Technology

Deformation monitoring refers to the measurement that monitors the change of monitored object using measuring instrument, and determines the deformation status of the target body by recording the changes of the representative discrete points on the target body. Its main purpose is to obtain the deformation characteristics of the spatial position and shape with time and vibration, and to analyze and judge the reasons for the deformation according to the obtained data. The three-dimensional laser scanning technology is also known as the real-scene replication technology. Compared with the traditional measurement technology, the three-dimensional laser scanning technology is high-speed, non-destructive, penetrating and accurate. Taking three-dimensional laser scanning as the technical medium and Deshengmen Gate (Watchtower) as an example, this paper provides technical analysis methods and case studies for the structural deformation monitoring of ancient castle buildings.

Coupled peridynamic model for geometrically nonlinear deformation and fracture analysis of slender beam structures

AbstractSlender beam structures can experience large displacements, large rotations and fractures, even if the structures are only subjected to small loads. A coupling model of peridynamics (PD) and classical continuum mechanics (CCM) for beam fracture analysis in geometrically nonlinear deformations is developed in this study. Firstly, the formulations of virtually nonlinear strain energy density of each incremental step are obtained by using the updated Lagrangian (UL) formulation and von Karman beam theory, then the nonlinear PD beam parameters are established on the geometrically nonlinear micro‐beam bonds via the principle of virtual work and homogenization. Secondly, the coupling model of PD and CCM for geometrically nonlinear beams is proposed, for which the morphing method is applied to create a balance between the stiffness of geometrically nonlinear CCM beam model and the weighted coefficients of geometrically nonlinear PD beam model. Thirdly, a new fracture criterion for PD beam models considering the effect of geometrical nonlinearity is adopted. Finally, the large deformation and fracture analysis of straight beam, spiral slender beam and complex frame subjected to different loading conditions illustrate the validity and accuracy of the proposed PD‐CCM coupling model.

Deformation Analysis of Binary Tree Structures by Transfer Matrix Method

Deformation Analysis of Binary Tree Structures by Transfer Matrix Method

Approaches to the study of deformations in permafrost soils

The object of the study is the processes of metamorphism of frozen rocks, including structural restructuring, as well as plastic and brittle deformations of underground ice. In geocryology, many experts note the importance of considering the processes of deformation of frozen rocks. At the same time, the deformed rocks themselves do not stand out in a separate category, which makes it difficult to study the development of cryogenic geosystems after their formation. The main method used in this article is the analysis of the results of previous studies by various authors on the topic under consideration. The theoretical basis of the proposed approach is the provisions developed within the framework of the mechanics of frozen soils and structural ice science. The synthesis of the analyzed materials was carried out on the basis of a geosystem approach. In the proposed work, for the first time, a comparative analysis of structural deformations of various kinds of cryogenic formations was carried out. The relevance of the topic under consideration is due to the need to study the patterns of deformation of frozen rocks in natural conditions. Theoretically, this is important for a deeper understanding of the processes occurring in the cryolithozone. For practical purposes, work in this direction will allow us to more accurately assess the possibility of the development of dangerous engineering-geological processes with man-made impacts on frozen rocks. Changes in the structure of frozen rocks continue after the formation of the primary structure. Deformations, that is, violations of the primary addition, are an integral part of the structure of frozen rocks. Data on deformations of the primary cryogenic structure provide information about the history of the development of cryogenic geosystems that have already been formed. It is necessary to develop a classification of textural and structural deformations of the cryogenic structure of frozen rocks, in which a special type should be distinguished - metamorphosed ice formations. It is necessary to develop methods of structural and deformation analysis that allow establishing links between the observed deformations of the cryogenic structure and the processes occurring in frozen rocks.

Analysis and management of structural deformations through parametric models and HBIM workflow in architectural heritage

Maintaining the structure and ornaments of historical buildings is essential to preserve cultural heritage in any society. Thus, dating the state and the evolution of the elements requires a special treatment, including the application of both advanced numerical analysis and non-invasive data acquisition techniques. In the latter, making digital copies of geometries through 3D reconstruction models is of great interest to compare and analyse structural evolutionary data accurately. For this purpose, appropriate software with containers of information correlated to the parametric elements in a BIM environment should be used. However, it is imperative to advance from static to dynamic models to collect the structural transformations caused by both the pass of time and other factors. The methodology followed in this paper is based on the experimentation by creating digital twins. The portico of a courtyard in a historical building from the 18th century was used as test bed. Based on the bibliographical recommendations, the terrestrial laser scanner is applied as a technique to acquire accurate data. The point cloud is used as a referential auxiliary to survey the model in the BIM platform with the Revit software. To assess the quality of the model built and to analyse the structural deviations between the parametric model and the actual geometry, the Dynamo script is used. To validate the experimentation, structural deviations are measured using both the parametric model and the point cloud with CloudCompare, a software for data treatment. The results were very positive because the deviation between the data obtained by Dynamo© and CloudCompare in the most unfavourable construction unit was between 0.5 and 1.17 cm, so these techniques are highly appropriate to review visual records and to analyse structural deviations. This new approach presents a new gap in the 3D reconstruction to date and control architectural structures, particularly in historical buildings.

Stiffness prediction and deformation analysis of Cobalt-Chromium lattice structures: From periodic to functionally graded structures produced by additive manufacturing

Lattice structures are candidates for innovative design of orthopedic implants and other highly functional products. In particular, functionally graded structures can be employed to achieve the required strength and stiffness for optimal stress-strain distribution. Prediction of the real behavior of these structures is essential for effective design. In the present work, stiffness prediction and deformation analysis of Cobalt-Chromium lattice structures manufactured using laser-based Powder Bed Fusion additive manufacturing were carried out. The study was developed in two steps: compressive tests and Digital Image Correlation were performed on periodic structures, with the results used to predict the stiffness of two types of functionally graded structures. The proposed method was validated experimentally, with the predicted stiffness of structures designed with the proposed elementary units within 6.1% for all tested cases. An array of stiffness data was then defined to allow free design of graded structures foreseeing specific compressive properties. The mechanical properties and deformation behavior of the structures were also investigated, with the local strain distribution mapped and compared to global deformation values.

Deformation analysis of surface and bronchial structures in intraoperative pneumothorax using deformable mesh registration

The positions of nodules can change because of intraoperative lung deflation, and the modeling of pneumothorax-associated deformation remains a challenging issue for intraoperative tumor localization. In this study, we introduce spatial and geometric analysis methods for inflated/deflated lungs and discuss heterogeneity in pneumothorax-associated lung deformation. Contrast-enhanced CT images simulating intraoperative conditions were acquired from live Beagle dogs. The images contain the overall shape of the lungs, including all lobes and internal bronchial structures, and were analyzed to provide a statistical deformation model that could be used as prior knowledge to predict pneumothorax. To address the difficulties of mapping pneumothorax CT images with topological changes and CT intensity shifts, we designed deformable mesh registration techniques for mixed data structures including the lobe surfaces and the bronchial centerlines. Three global-to-local registration steps were performed under the constraint that the deformation was spatially continuous and smooth, while matching visible bronchial tree structures as much as possible. The developed framework achieved stable registration with a Hausdorff distance of less than 1 mm and a target registration error of less than 5 mm, and visualized deformation fields that demonstrate per-lobe contractions and rotations with high variability between subjects. The deformation analysis results show that the strain of lung parenchyma was 35% higher than that of bronchi, and that deformation in the deflated lung is heterogeneous.

Growth of forearc highs and basins in the oblique Sumatra subduction system

Based on structural deformation analysis in the oblique Sumatra subduction system, we review uplift mechanisms of the forearc high and formation of the forearc basin. The development of the forearc high has been attributed to the flexural uplift, basin inversion, uplift of older accretion wedge, and backthrust in the landward margin of the accretion wedge. Observation of recently acquired seismic reflection data shows that the interplay between trenchward-vergent thrusts and arcward-vergent backthrusts has played a major role in the uplift of forearc high. The uplifted sediments on the forearc high were previously formed in a forearc basin environment. The present-day morphology of the forearc high and forearc basin is related to the uplift of the accretionary wedge and the overlying forearc basin sediments during Pliocene. Regardless of obliquity in the subduction system, the Sumatran forearc region is dominated by compression that plays an important role in forming Neogene basin depocenters that elongated parallel to the trench.

Calculated Model of Endurance Limit Estimation Based on Structural-Strain Analysis of the Critical Condition of Ferrite-Perlite Steels with Macrocracks in Ship Structures

In this study, a structural-deformation analysis of the process of crack development is performed, on the basis of which an engineering methodology is developed for assessing the endurance limit and resource of large-sized structures. A simple analytical dependence (correlation аналитическая зависимость) was obtained, which allows one to determine the critical size of macrocracks for ferritic-pearlitic steels without using the well-known Griffith formula. The results of calculating the cracks critical lengths of various steels depending on their yield strength are presented. The analytical dependence of the calculation of the fatigue limit for the most dangerous symmetric loading cycle according to the standard set of mechanical characteristics of ferrite-pearlite steel is presented. The obtained results make it possible to calculate the endurance limit of structural elements of marine equipment and other structures subject to cyclic loads

Analysis of structural and age deformations of population - regional aspect

Structural-age-related changes of the population of Ukraine on the example of the graphic of deformation of a pyramid 2001 year аre considered. It is established that considerable scales of structural deformations: negative deviations in age pyramids, are connected by considerable losses of the population and the corresponding demographic waves. The technique of the quantitative analysis of gender and age pyramids is developed and approved. The reasons of negative and positive deformations both in Ukraine as a whole and in its regions are analyzed. Regions on intensity and amplitude structurally-age deformations are systematized. Three main groups are allocated and as an example one region from each group are characterized. The analysis of structural deformations of the population of Ukraine and its regions is carried out.

Subduction characteristics of the ordovician erlangping back-arc basin in the east qinling mountains, china: implications for the tectonic evolution of the northern margin of the proto-tethys ocean

ABSTRACT A relatively complete trench–arc–basin system developed on the northern margin of the Proto-Tethys Ocean, and its subduction mode is key in reconstructing the tectonic evolution of the northern Proto-Tethyan margin. The Erlangping Group in the East Qinling Mountains is thought to be the product of subduction in the back-arc basin. Analysis of the metamorphism and deformation recorded by the group may elucidate the subduction mode of the back-arc basin. In this study, the tectonites in the southern and northern parts of Erlangping Group are taken as the research object, and their dynamic parameters such as geometry, kinematics and vorticity are determined by field observation and indoor tectonic deformation analysis. Deformed rocks in the northern part of the Erlangping Group are mainly feldspathic schists, primary mylonite, and mylonite, and the deformed rocks in the southern part of the Erlangping Group are mainly schists. The geometric characteristics of Erlangping group show that the foliation (30°–60°∠ 42°–70°) and dip lineation (5°–62°∠ 33°–51°) in the north of Erlangping group incline to NE, while the foliation (174°–234°∠ 50°–80°) and dip lineation (195°–230°∠ 45°–65°) in the South incline to SW; the kinematic characteristics show that both sides of Erlangping Group move under Qinling Group and Kuanping Group, respectively. Kinematic vorticity calculation shows that the vorticity values of the northern and southern parts of Erlangping Group are 0.79 and 0.78, respectively, both of which are more than 0.75, indicating that the shear type is dominated by simple shear and supplemented by pure shear. The average values of kinematic vorticity on the northern and southern parts of Erlangping Group are 0.78 and 0.79, respectively, both more than 0.75, indicating that subduction was dominated by simple shear, with minor pure shear deformation. The subduction deformation temperature range of Erlangping Group is estimated to be 380 ~ 500°C by the degree of quartz dynamic recrystallization. There is a positive correlation between the differential stress value σ (southern parts of Erlangping Group: 17.84–46.50; northern parts of Erlangping Group: 17.87–71.66) and strain rate ε (southern parts of Erlangping Group: 2.09 × 10–14 – 2.51 × 10–13; northern parts of Erlangping Group: 2.08 × 10–14 – 8.23 × 10–13) during subduction, while the grain size of dynamically recrystallized quartz is negatively correlated with strain rate. The specific performance is that in the northern part of Erlangping Group, from the Waxuezi–Qiaoduan shear zone to the Damiao–Dongjie shear zone, with the increase of the particle size of dynamically recrystallized quartz particles, the values of differential stress and strain rate gradually decrease, and have the same performance in the southern part of Erlangping Group. Through the above structural deformation analysis, combined with the previous research results on the material composition, sedimentary formation, magmatism, metamorphism and deformation of the Erlangping back-arc basin, it is considered that the Erlangping back-arc basin has the characteristics of bidirectional subduction during the late Palaeozoic subduction.*

Analysis of mechanical stress and structural deformation on a solar photovoltaic panel through various wind loads

Analysis of mechanical stress and structural deformation on a solar photovoltaic panel through various wind loads

The simplified analysis method of nonlinear buckling and displacement of latticed structure

In order to simplify the modeling process of building complex lattice structures by finite element analysis software, a simplified method for nonlinear buckling and deformation analysis of lattice structures based on equivalent inertia moment method is proposed. By comparison with the displacements, the latticed structure is equivalent to a solid structure, and the expression of the equivalent inertia moment of a typical latticed structure is given. The finite element analysis software ANSYS is used to analyze the buckling problem and the deformation of latticed structure and the equivalent solid structure, furthermore, the load-displacement curves of the actual structure and equivalent model are obtained. The results show that the simplified analysis method of nonlinear buckling and deformation of latticed structure is feasible and can satisfy the needs of engineering design.