Deformation Analysis Of Structures Research Articles

Dynamic serviceability and safety reliability analysis of aging PC girder bridges with non-prestressed reinforcement considering concrete shrinkage, creep and stochastic vehicle load flows

Prestressed concrete (PC) bridges’ service performance displays time-dependency due to several factors including concrete shrinkage, creep, resistance degradation, and stochastic vehicle load flows. These non-stationary vehicle load flows, combined with concrete shrinkage, creep, and resistance degradation, result in sequential alterations of internal forces and deformations in simply supported PC girder bridges, ultimately influencing their dynamic reliability. This study proposes a robust methodology that considers the impact of traffic loading, shrinkage, and creep to analyze the dynamic reliability of simply supported PC girder bridges through the development of a load probability model. A stochastic model for truck loads is generated using motion measurement data, which can be used to calculate bridge internal forces and subsequent quantitative analysis of structural deformation due to shrinkage and creep. Subsequently, the formula for the first exceedance probability under resistance degradation is presented and validated through Monte Carlo simulation. Reliability analysis is conducted for both serviceability and load carrying capacity limit states to assess the impact of shrinkage, creep, and increased mean vehicle load on structural reliability. The proposed method offers the theoretical foundation and practical guidance for assessing the structural health status of in-service bridges, thereby providing valuable insights into their long-term performance and maintenance requirements.

Deep learning enhanced fluid-structure interaction analysis for composite tidal turbine blades

A precise and cost-effective prediction tool for fluid-structure interaction (FSI) analysis is crucial for optimizing the structural design of tidal turbine blades. However, the high computational costs associated with fluid dynamic analysis pose a significant challenge, as the current lack of efficient FSI prediction methods hinders the advancement of cutting-edge tidal turbine designs. To address this issue, this paper proposes a novel consolidated framework that integrates deep learning convolutional neural networks (CNN) with blade element momentum (BEM) theory and finite element method (FEM) to perform deformation analysis of turbine blade structures. The proposed CNN-BEM-FEM integrated framework efficiently identifies the geometric features and predicts the hydrodynamic parameters of turbine blades and thus, achieving accurate assessments of the structural behavior of tidal turbines. The study applies two-step verification procedures to validate the prediction accuracy of the CNN-BEM-FEM framework and the result demonstrates excellent agreement with experimental tests for hydrodynamic performance and blade deformation. When compared with the static one-way FSI calculated by Ansys Workbench software, the computational efficiency of CNN-BEM-FEM framework increases by more than 18 times, with discrepancies in blade deformation and equivalent stress calculations generally less than 5 %. By applying the proposed method to predict the FSI performance of tidal turbine blades with various shear web structures, the practical applicability for composite turbine blade design is successfully demonstrated. The results underscore the potential of the CNN-BEM-FEM framework as an efficient and accurate prediction tool for optimizing the structural design of tidal turbine blades.

Taguchi–gray relational analysis of eccentricity and tilt of multilens module mount fabricated by injection compression molding

AbstractThis study utilizes the mold flow analysis technique of the injection compression molding (ICM) process, combined with the Taguchi–gray relational analysis (GRA), for process optimization analysis on the roundness of the lens holes and the flatness of the lens mount in a 4 × 4 planar multilens array mount. After manufacturing simulation analysis, the eccentricity and tilt information of the lens mount was further evaluated optically through spot diagram analysis upon inserting the same glass lenses. The results showed a positive correlation trend between roundness and flatness in structural deformation analysis, indicating that improving the overall flatness of the lens mount can enhance the roundness of the lens holes. In optical analysis, better improvements in the lens tilt angle were achieved through GRA. In conclusion, aiming to simultaneously improve the roundness of the lens holes and the overall flatness of the lens mount, the Taguchi–GRA method can achieve the optimization objectives. In terms of optical performance, by optimizing for roundness, it is possible not only to reduce the diameter of the light spot but also to simultaneously reduce the offset displacement of the light spot center on the screen. The method proposed in this paper can serve as an analytical model for the design and fabrication of plastic multilens mount.

A hierarchic isogeometric hyperelastic solid-shell

AbstractThe present study aims to develop an original solid-like shell element for large deformation analysis of hyperelastic shell structures in the context of isogeometric analysis (IGA). The presented model includes a new variable to describe the thickness change of the shell and allows for the application of unmodified three-dimensional constitutive laws defined in curvilinear coordinate systems and the analysis of variable thickness shells. In this way, the thickness locking affecting standard solid-shell-like models is cured by enhancing the thickness strain by exploiting a hierarchical approach, allowing linear transversal strains. Furthermore, a patch-wise reduced integration scheme is adopted for computational efficiency reasons and to annihilate shear and membrane locking. In addition, the Mixed-Integration Point (MIP) format is extended to hyperelastic materials to improve the convergence behaviour, hence the efficiency, in Newton iterations. Using benchmark problems, it is shown that the proposed model is reliable and resolves locking issues that were present in the previously published isogeometric solid-shell formulations.

Corotational isogeometric shear deformable geometrically exact spatial form beam element for general large deformation analysis of flexible thin-walled beam structures

In this paper, a new 3D generic order corotational geometrically exact beam element undergoing arbitrarily large deformations is presented. The novelty of the formulation lies in the use of the standard corotational framework, that is the decomposition into rigid body motion and pure deformation, to derive not only the objective, path-independent and singularity-free spatial exact strain measure but also the internal force and the consistent tangent stiffness matrix. The new formulation is derived by firstly conducting the consistent linearization of the weak formulation for the equilibrium equations of Reissner–Simo theory in the spatial form. By constructing a co-rotated frame that continuously rotates and translates with the element, the nodal strain-producing deformations can be extracted with the rigid-body translations and rotations removed from the element total motion. Subsequently, the corotational deformation variables are exploited to establish the distribution of deformation field within the beam element through B-spline basis functions, and derive the invariant and path independent exact strain measure in the spatial form by Lie derivative formalism. Through performing the variational operations of the compact transformation between corotational and global variables, the consistent tangent stiffness matrix are derived in closed form of the discrete variables for deformation field of any order. The proposed formulation is applicable to not only low-order two-node geometrically exact elements but also high-order multi-node straight or curved ones. The accuracy and robustness of the new formulation are demonstrated through the solutions of various benchmark problems.

Structural geology and deformation analysis in the Búzios-Itapu area, Santos Basin — offshore Brazil

Despite their proximity, the Búzios and Itapu oil fields in the Santos Basin have different structural configurations. The study of the deformation pattern of the area and the relationship of the observed structures with the tectonic evolution of the basement is important to understand the geologic setting and evolution of the studied oil fields. In this work, a 3D PSDM seismic volume calibrated with well data was used to characterize the different types of structures, the distinct structural domains that occur in the Pre-Salt of the Búzios and Itapu fields, and the relationship between the basement trends and the structures in the sedimentary section. The Búzios field is formed by a series of half-grabens and horsts elongated in the NE-SW and NW-SE trends. Over the structural highs, a wide carbonate platform was developed. The Itapu field is a structural high related to a single elongated half-graben with a N-S main trend. The main structural pattern in the area is defined by normal faults that indicate an extensional process, typical of rift evolution. However, there are several structures that show indication of oblique-like deformation with strike-slip displacements, throughout the studied area. A very important issue is the discussion of the hierarchy of the observed structures, both rift extensional structures, and the oblique-like ones.

A high‐order shell finite element for the large deformation analysis of soft material structures

SummaryThis work proposes a higher‐order unified shell finite element for the analysis of cylinders made of compressible and nearly incompressible hyperelastic materials. The nonlinear governing equations are derived employing the Carrera unified formulation (CUF), thanks to which it is possible to build shell elements with the capability to capture three‐dimensional (3D) transverse and out‐of‐plane effects. The material and geometric nonlinearities are expressed in an orthogonal curvilinear reference system and the coupled formulation of hyperelastic constitutive law is considered. The principle of virtual work and a total Lagrangian approach is used to derive the nonlinear governing equations, which are solved by a Newton–Raphson scheme. The numerical investigations deal with a curved arch and both thick and thin cylinders subjected to line and point loadings. The obtained results are validated by comparing them with those from the literature. They demonstrate the reliability of the proposed method to analyze compressible and incompressible hyperelastic shell structures.

An elastoplastic damage model for concrete considering the influence of mesostructure on transverse deformation

The deformation of mesostructures such as micropore collapse or microcrack expansion within concrete can hugely influence its macro transverse deformation. This deformation characteristic is not effectively characterized in existing elastoplastic damage constitutive models based on micromechanics. This discrepancy can result in substantial disparities between the calculated results and the actual situation when carrying out the stress and deformation analysis of concrete structures. Through an in-depth examination of how micropore collapse and microcrack shear expansion affect transverse measurable strain, a new calculating method for concrete transverse deformation is established according to its actual evolution characteristics. The reliability of the proposed method is verified based on the triaxial compression test results. Research results indicate that the transverse deformation of concrete increases slightly before the peak deviatoric stress, and significantly in the post-peak stage. If deformation is restricted, changes in transverse deformation can profoundly affect the stress state of concrete. Micropore collapse reduces the macroscopic transverse deformation of concrete, while microcrack expansion has the opposite effect. The strain caused by micropore collapse and microcrack expansion can be deemed as derivative strain of plastic strain, and an influence coefficient can be used to characterize the impact of these two factors on macroscopic transverse deformation. It is proposed that the total transverse strain consists of elastic strain and the product of plastic strain and plastic strain influence coefficients. The development characteristics of concrete transverse deformation can be effectively captured when describing the plastic strain influence coefficient using an arctangent function.

Structural Enhancement and Thermal Deformation Analysis of Antenna Arrays in Vehicle-Mounted Phased Array Radar: A Heat Dissipation Perspective

Structural Enhancement and Thermal Deformation Analysis of Antenna Arrays in Vehicle-Mounted Phased Array Radar: A Heat Dissipation Perspective

A Numerical Method-Based Analysis of the Structural Deformation Behaviour of a Turkish String Instrument (Cura Baglama) under Varying String Tensions

This study focuses on the structural design analysis of a cura baglama, a traditional Turkish string instrument that does not have in place a regulated set of manufacturing standards to follow. The aim therefore is to introduce a structural deformation analysis for a sample cura baglama in three different string tensions via a numerical method-based engineering analysis technique. The three-dimensional solid model of a sample cura baglama was created using a 3D scanner and parametric 3D solid modelling software. Based on experimental frequency analysis, structural deformation analyses of the instrument were conducted using finite element method-based engineering simulation techniques. The simulation results revealed useful visual and numerical outputs related to the deformation behaviour of the instrument under pre-defined boundary conditions. A maximum deformation of 0.223 mm on the soundboard (at the D3 tune) and a maximum equivalent stress of 18.325 MPa on the bridge (at the D3 tune) were calculated. The outputs of this research contribute to further research into the usage of numerical method-based deformation simulation studies related to the standardisation, development, and preservation of such traditional string instruments.

Chickies Rock, a striking promontory on the Susquehanna River: the early Cambrian type locality of the trace fossilSkolithosand a model site for structural analysis

AbstractChickies Rock rises abruptly from the east bank of the Susquehanna River at Columbia, Pennsylvania, where it breaks through a ridge held up by massively bedded quartzite. Here in the 1830s, Samuel Haldeman recognized long straight tubes that he later described asSkolithos linearis, penetrating the quartzite. Uncertain about the nature of these cylindrical ‘vermiform or linear’, unbranched ‘stems’, Haldeman first treated them as a subgenus ofFucoides, to which root-like traces were then often assigned. By the time James Hall first illustrated the species in 1847, Haldeman was sure they were burrows of a worm-like animal, as the name he had chosen implied. Since 1960, Donald Wise has developed a detailed analysis of structural deformation of the Chickies Anticline, using theSkolithosburrows as ‘plumb-bobs’ against which Taconic rotation of the rock fabric can be measured. Wise showed that later Alleghanian deformation produced prominent folds with external rotation up to twice as great as that of the rock fabric itself. Now conserved as a county park, Chickies Rock attracts many visitors. Its cliff-top is a superb viewpoint from which to contemplate progressive westward migration of the Appalachian drainage divide, ongoing since the late Jurassic opening of the Atlantic Ocean.

THE DYNAMIC-STATIC METHOD (DSM) FOR STRUCTURAL DISPLACEMENT ANALYSIS USING THE EXAMPLE OF A WOODEN CHURCH IN DOMACHOWO (POLAND)

Abstract. Medieval architecture in Poland is not widely represented in the tangible cultural heritage. A preserved structure with traces of medieval architecture is the parish church in Domachowo in southern Greater Poland (Wielkopolska). Due to numerous alterations and modernisations, it is now a complex structure showing clear signs of a damaged original geometry.For this reason, a project was initiated to measure the stability of the structure, especially under the influence of extreme external factors: mainly gusts of wind and uneven sun illumination. The implementation of the project required using two methods of measurement: static, at fixed time intervals, and dynamic, recorded on an ongoing basis during the operation of variable loads. The outcomes consisting of a combination of both methods and the unconventional use of precise inclinometers for measuring wooden structures, opens up new possibilities for real-time analysis of structural deformations and ongoing monitoring of technical conditions.The subject of this paper is to present the methodology of the conducted static-dynamic measurements (DSM) and the interpretation of their results, mainly in the context of assessing accuracy, stability of long-term readings with inertial sensors, and basic structural assessment.

Hydrodynamics and solid mechanics structural analysis of mold deformation in nanoimprint lithography

A hybrid model has been developed to study the dynamic filling process of the resist and to investigate the subsequent capillary force induced structural deformation of the imprint mold during nanoimprint lithography (NIL). The dynamic behavior of resist filling with varied physical parameters was investigated by a hydrodynamic model. The capillary force induced deformation of mold structures was modeled using beam bending mechanics for various mold structures. Theoretically calculated results were cross-validated with finite-element simulations using fluid–structure interaction and two-phase flow methods. Based on the theoretical analysis, a general parameter of critical aspect ratio is proposed as the guideline for the design of NIL mold, especially for the NIL mold with a high aspect ratio and ultra-high resolution. The theoretical investigation helps to deepen the understanding of the dynamic mechanism of resist filling and structural deformation, and enables the optimization for high-fidelity NIL.

PyTorch-FEA: Autograd-enabled finite element analysis methods with applications for biomechanical analysis of human aorta

Background and objectivesFinite-element analysis (FEA) is widely used as a standard tool for stress and deformation analysis of solid structures, including human tissues and organs. For instance, FEA can be applied at a patient-specific level to assist in medical diagnosis and treatment planning, such as risk assessment of thoracic aortic aneurysm rupture/dissection. These FEA-based biomechanical assessments often involve both forward and inverse mechanics problems. Current commercial FEA software packages (e.g., Abaqus) and inverse methods exhibit performance issues in either accuracy or speed. MethodsIn this study, we propose and develop a new library of FEA code and methods, named PyTorch-FEA, by taking advantage of autograd, an automatic differentiation mechanism in PyTorch. We develop a class of PyTorch-FEA functionalities to solve forward and inverse problems with improved loss functions, and we demonstrate the capability of PyTorch-FEA in a series of applications related to human aorta biomechanics. In one of the inverse methods, we combine PyTorch-FEA with deep neural networks (DNNs) to further improve performance. ResultsWe applied PyTorch-FEA in four fundamental applications for biomechanical analysis of human aorta. In the forward analysis, PyTorch-FEA achieved a significant reduction in computational time without compromising accuracy compared with Abaqus, a commercial FEA package. Compared to other inverse methods, inverse analysis with PyTorch-FEA achieves better performance in either accuracy or speed, or both if combined with DNNs. ConclusionsWe have presented PyTorch-FEA, a new library of FEA code and methods, representing a new approach to develop FEA methods to forward and inverse problems in solid mechanics. PyTorch-FEA eases the development of new inverse methods and enables a natural integration of FEA and DNNs, which will have numerous potential applications.

Finite deformation analysis of electro-active shells

In this contribution, a novel nonlinear formulation for the finite deformation analysis of shell-like structures made of dielectric polymers and subject to electrical loading is developed. The kinematics of mechanical deformation is described via a seven-parameter shell model. Moreover, a second-order Taylor expansion, containing three parameters, is proposed to approximate the electrical potential through the thickness of the shell. The combined mechanical and electrical parameters constitute a ten-parameter electro-shell model. After developing the variational formulation of the problem, a nonlinear finite element formulation for the numerical solution of the coupled electromechanical problem is also developed. The formulation is further enriched by the enhanced assumed strain method to alleviate locking in thin shells. Finally, the applicability of the proposed formulation in several benchmark examples is demonstrated. In particular, it is shown that the formulation can capture the results available in the literature with high accuracy.

Structural deformation analysis by landslide in Reina del Cisne sector - Paccha using LiDAR scans and CloudCompare software

Structural deformation analysis by landslide in Reina del Cisne sector - Paccha using LiDAR scans and CloudCompare software

Investigation and Analysis of Stress and Deformation Monitoring of Long-Span Steel Roof Trusses

Structural stress and deformation monitoring and analysis were carried out for the 54 m long-span steel roof truss. To ensure the safety of the construction process, the stress and deformation of the steel roof trusses were monitored throughout the construction process. The numerical modeling of the structures with six different working conditions was carried out, and the points with the most critical values of stress and deformation were found. This work provides a theoretical basis for field monitoring during and after construction. The results show that the maximum vertical displacement of a steel roof truss during all modeled working conditions and the maximum measured displacement are within the Chinese building code’s requirements. The maximum value of stress found during analysis of the structure during the construction process and the maximum measured stress are much less than the yield stress. The structural stress remains in the elastic range. The reasons for the differences between the calculated and measured results were analyzed.

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.