Deformation Characteristics Of Structure Research Articles

Methodological approach for reducing computational costs of vehicle frontal crashworthiness analysis by using simplified structural modelling

ABSTRACTA challenge in the design and optimisation of the vehicle front structures is the high computational costs required for crash analysis. A methodological approach to simplifying finite element vehicle models and crash barriers is presented in this paper. The methodology uses global deformation characteristics of structures which are obtained from the global crash model. For the simplification of the vehicle crash model, structural regions which sustain only elastic deformations during the frontal crash are replaced by kinematic numerical representations which describe both stiffness and load paths at the interface of the substituted structures. Verification studies of the simplified vehicle model show a very good agreement of the global and local structural response during the frontal crash. Further simplifications were applied to the offset deformable barrier by replacing its detailed crushing behaviour by kinematic descriptions. Through the combined use of both simplified numerical representations, the computational cost of a Euro new car assessment program (NCAP) offset crash analysis can be reduced by around 92%. With the obtained time reduction, structural optimisation studies of the remaining structure can be conducted efficiently for the identification of weight reduction potentials.

Capturing the cracking characteristics of concrete lining during prototype tests of a special-shaped tunnel using 3D DIC photogrammetry

Capturing the cracking process during prototype loading tests of segmental lining is crucial for the design of tunnel structures. This paper presents an application case history of 3D digital image correlation technique to monitor the cracking behaviour of concrete lining during prototype loading tests of a special-shape tunnel. The principles based on the displacement field to identify cracks, to determine the onset of cracking and to calculate the crack width were defined. The cracking behaviour at the three measurement regions was discussed. In particular, three distinct cracking stages corresponding to different deformation statuses were identified including a primary deformation stage with small deformation, a steady-state cracking stage with a constant cracking rate and an accelerating cracking stage with an increasing cracking rate. The bearing capacity of segment structures corresponding to the crack width prescribed by the Chinese design code was obtained. This study has shed light on the application of non-contacting optical techniques to capture the deformation characteristics of concrete structures in the full-scale experiments as well as civil engineering practice.

A molecular dynamics investigation of hydrostatic compression characteristics of mineral Jennite

This paper focuses on the study of mechanical behavior and deformation of mineral Jennite, under isothermal hydrostatic compression using Molecular Dynamics (MD) modeling. Atomistic structure of mineral Jennite is considered as a choice for representing calcium silicate hydrate (C-S-H), a key constituent in hydrated cement paste. The present work focuses and presents a molecular dynamics simulation approach to ascertain hydrostatic compression characteristics of mineral Jennite. The pressure–specific volume, and specific internal energy–specific volume relationships under isothermal hydrostatic compression conditions were determined. For the pressures ranging from 0.0001GPa to 5GPa, computational modeling results indicated that a linear relationship may be sufficient when describing the pressure–specific volume relationship. The results obtained in this study compared well with experimental and theoretical results recently published by other researchers. Additionally, a quadratic function was found to be appropriate to describe the specific energy–specific volume relationship, for the same pressure range used for studying the pressure–specific volume relationship. The pressure–specific volume, and specific internal energy-specific volume relationships reported in this paper are useful for further estimation of pressure–specific volume constitutive Hugoniot of the nanoscale mineral Jennite. Additionally, MD approach discussed and presented in this paper can be applied to understand hydrostatic compression behavior and deformation characteristics of other atomistic structures representing C-S-H. Further, the computational material modeling approach discussed in this paper provides an alternative methodology that can aid in the understanding of the deformation mechanisms and developing constitutive relationships from atomistic structures of materials.

Structural analysis and deformation characteristics of the Yingba metamorphic core complex, northwestern margin of the North China craton, NE Asia

The presence of the Yingba (Yinggete–Bagemaode) metamorphic core complex (MCC) is confirmed near the Sino-Mongolian border in China. We report its structural evolution and the rheological features of ductile shear zones within this complex. Three deformations (Ds, Dm, and Db) since the Late Jurassic are identified. Ds is characterized by ductile structures that resulted from early NW-oriented, low-angle, extensional ductile shearing. Dm is associated with partial melting and magmatic diapirism, which accelerated the formation of the dome-like geometry of the Yingba MCC. Synchronously with or slightly subsequently to Ds and Dm, the Yingba MCC was subjected to brittle, extensional faulting (Db), which was accompanied by the exhumation of the lower crust and the formation of supracrustal basins. The ductile shearing (Ds) developed under greenschist-to amphibolite-facies metamorphic conditions (400–650 °C), as indicated by microstructures in quartz and feldspar, quartz [c] axis fabrics, and two-feldspar geothermometry. The mean kinematic vorticity estimates of 48–62% show a pure shear-preferred flow during Ds. The Yingba MCC provides an excellent sample that recorded an intermediate to high temperature shearing, which also implies the widely extensional regime in northeastern Asia at that time.

Numerical Simulation of Deformation Characteristics of Diaphragm Wall Supporting Structure of Deep Foundation Pits

It was numerically simulated in the paper of the deformation characteristics of the diaphragm wall in the deep foundation by using MIDAS/GTS numerical simulation software which combined with the engineering practice of deep foundation pit of Hefei New Traffic Building and the actual construction sequence of the project in order to study the deformation characteristics of the diaphragm wall. The deformation regularity of the embossed belly shape of the diaphragm wall is shown in the whole construction period. The maximum displacement value of the wall occurs near the excavation surface and falls within a certain range. The conclusion provides a reference for future similar projects throughout to compare the monitoring data with the rationality, and correctness of the modeling and simulation are verified.

Steady, dynamic and structural deformation (three interval thixotropy test) characteristics of gluten-free Tarhana soup prepared with different concentrations of quinoa flour.

Malnutrition is currently widespread in many areas of the world. Therefore, it must be focused on the cheap, but nutritious plant protein and mineral sources, such as legume and cereals. Several recent studies have showed the successful formulation of pseudocereal containing cereal based products. Tarhana is a traditional fermented food made of mainly a mixture cereal and yoghurt. Tarhana or tarhana-like products have been enriched or replaced with cereal and pseudocereal. In this research, the applicability of QF in traditional tarhana production were investigated. As a result, it is advisable to replace wheat flour with QF in products such as tarhana, couscous, noodle and pasta formulation for nutritional and sensory properties enrichment. The results suggest that QF can be used in gluten-free tarhana formulations to enhance rheological properties.

The impact of effective stress and gas slippage on coal permeability under cyclic loading

The determination of the effective stress coefficient of porous media (such as coal) remains a controversial issue. The purpose of this paper is to determine the effective stress coefficient of coal during gas penetration and to investigate the impact of effective stress and gas slippage on coal permeability under cyclic loading conditions. Analyzing the evolution law of coal anisotropic permeability with effective stress allows the deformation characteristics of the coal's internal structure, such as cleat or bedding, to be studied. The effective stress coefficient of long flame coal is obtained through modified permeability models based on experimental data. Test results show that the slippage effect significantly influences the permeability of coal samples, specifically in the range of low pore gas pressure, and that the effect of gas slippage is larger than that of effective stress. Permeability decreases gradually when effective stress increases, but it increases during unloading, and ascending and descending curves show significant irreversibility of permeability. Moreover, PLR (permeability loss rate) and IPLR (irreversible permeability loss rate) results indicate that the influence of effective stress on permeability perpendicular to bedding is greater than that of permeability parallel to bedding and that the ability of the cleat to resist deformation induced by effective stress is weaker than that of bedding. Under identical pressure conditions, the cleat shows more vulnerability and produces larger plastic deformation.

A peridynamic theory for linear elastic shells

A state-based peridynamic formulation for linear elastic shells is presented. The emphasis is on introducing, possibly for the first time, a general surface based peridynamic model to represent the deformation characteristics of structures that have one geometric dimension much smaller than the other two. A new notion of curved bonds is exploited to cater for force transfer between the peridynamic particles describing the shell. Starting with the three dimensional force and deformation states, appropriate surface based force, moment and several deformation states are arrived at. Upon application on the curved bonds, such states yield the necessary force and deformation vectors governing the motion of the shell. By incorporating a shear correction factor, the formulation also accommodates analysis of shells that have higher thickness. In order to attain this, a consistent second order approximation to the complementary energy density is considered and incorporated in peridynamics via constitutive correspondence. Unlike the uncoupled constitution for thin shells, a consequence of a first order approximation, constitutive relations for thick shells are fully coupled in that surface wryness influences the in-plane stress resultants and surface strain the moments. Our proposal on the peridynamic shell theory is numerically assessed against simulations on static deformation of spherical and cylindrical shells, that of flat plates and quasi-static fracture propagation in a cylindrical shell.

Deformation Characteristics of Track Structures for Level Crossings Subjected to Heavy Forklift Load

Level crossings or paved ballasted tracks laid in freight train container yards are subjected to train loads and forklift loads. Those asphalt pavements in the level crossings or paved ballasted tracks are designed using performance-based design method. Nevertheless, in the conventional design for ballasted tracks itself at the level crossing or paved ballasted tracks in the freight container yards in Japan, truck loads or forklift loads are generally not taken into account, and therefore, heavy duty truck loads or 12ft-container-forklift loads had not induced a typical problem to level crossing structures or paved ballasted tracks. However, because of the recent increase in the transportation of the large marine containers on freight trains, very large forklifts have been increasingly introduced to freight container yard. Maximum wheel loads of those large forklifts reach up to 500kN. Consequently, damages to level crossings and paved ballasted tracks in freight container yard are increasing. Concrete slab tracks are considered to be effective track structure to reduce the deformation of roadbeds or subgrades which are subjected to heavy forklift loads. However, to maintain the concrete slab tracks in the freight container yards in a decent condition, it is necessary to design the roadbeds and subgrades properly to avoid excessive deformation, because once the deformation are induced bebeath concrete slab tracks, it is not easy to correct track irregularity. To deal with above issues, deformation characteristics of subgrades, roadbeds and track structure under the heavy forklift loads were investigated using small scale model tests and full scale model tests in this study. In the scale model tests, moving wheel loads were applied to an asphalt paved ballasted track model and concrete slab model. In the full scale model tests, train loads and heavy forklift loads were applied on the asphalt paved ballasted track and concrete slab track. Through those tests, it was confirmed that the load applied by heavy forklift have predominant effect on the deformation characteristics of asphalt paved ballasted track. Besides, it was confirmed that the concrete slab track effectively reduces the vertical stress applied on the roadbed and subgrade.

Re-determining source faults of the Upper Cretaceous Putaohua oil layer in Sanzhao sag of Songliao Basin, NE China

Abstract From the deformation characteristics of two walls of a fault caused by fault activities, the activation of faults in the critical moment of oil and gas accumulation (structural inversion period) was analyzed to determine the source faults in the Upper Cretaceous Putaohua oil layer of the Sanzhao sag in Songliao Basin. Based on the previous classification and research results of activity patterns of the faults in the Sanzhao sag, the analysis of the structural deformation characteristics during the deposition of the 2nd and 3rd members of the Upper Cretaceous Nenjiang Formation and the inversion reveals that the feature of cutting to T 06 reflection layer (bottom interface of the third member of the Nenjiang Formation) can not be taken as the basis to judge whether the faults were activated during the inversion or not. But during the structural inversion period, the structural deformation caused by faults would lead to fault-propagation inverted folds and fault-bend inverted folds, which would further lead to obvious deformation differences between hanging walls and foot walls of faults, this can be taken as the basis to determine if the faults were activated or not in the inversion period, and then the source faults of the Putaohua oil layer can be determined. Furthermore the source faults can be divided into two kinds, concealed faults and penetrating faults, according to if the source faults cut through layers of inversion period or not. These two kinds of source faults show more obvious control over the planar oil distribution in the Putaohua layer than the previous study results.

Program- and Goal-Oriented Approach to Organization of Monitoring Deformations of Buildings and Structures

A new program-and goal-oriented approach is offered for organization of geodetic monitoring of deformations of buildings and structures, which unlike the deterministic approach requiring strict adherence to the basic provisions of scientifically unjustified, obsolescent regulatory materials, helps synthesize the main parameters of the repeated geodetic observations on a scientifically justifiable basis with representativeness and ample reliability of determining deformation characteristics of buildings and structures.

Dynamic test procedure for crash–testing front structures

In determining the crashworthiness requirements of a new car design it is necessary to divide them into two groups: structure system requirements and interior system requirements. It is then necessary to devise test procedures to verify the specified requirements. The test procedure must be capable of measuring the deformation characteristics of the front structure and the effect of the components packed in the engine compartment. Static and dynamic test procedures were examined. The development of a dynamic test procedure that comes near to the ideal of a complete car test is described, and the value for design analysis of the results it yields is assessed.

Fast Dynamic Analysis of Complicated Beam-Type Structure Based on Reduced Super Beam Model

In this study, a new model-reduction method based on the fine finite-element model of complicated beam-type structure is presented, which can meet the needs of fast rough estimation of structural global dynamic performances in preliminary design. Based on the knowledge of deformation characteristics of beam-type structures, the plane cross-section assumption and displacement interpolation function of the beam is introduced to construct a localized physical reduction base vector. By dividing the structure into several parts, the finite-element method structural nodal degrees of freedom in each part are projected onto the nodal deflection and rotation degree of freedom of two master nodes at its two ends; the part of the structure is reduced into a super beam element. A free–free reduced super beam model with fewer degrees of freedom than the original complicated one is obtained by assembling the super beam elements in series. The accuracy of the reduced super beam model is further improved by modifying the stiffness matrix of super beam element and considering the effect of shear deformation in a rational way. Several examples for fast frequency and transient analysis of the original structure under different boundary conditions and dynamic load are presented, which demonstrate the feasibility and efficiency of the proposed method.

Study on Deformation Characteristics of Composite Lining Structure of Shield Tunnel

A three-dimensional refined model of composite lining is built with the example of shield tunnel of Xijiang water diversion project in Guangzhou by using finite element software. Segment opening and steel pile deformation characteristics are analyzed. Necessity of light material and steel pile is detailed explained. The results show that the maximal segment opening of composite lining is 0.361 millimeter. The bolts are in elastic state and not appear plastic deformation, so segment without leakage. Steel pipe strain curve is approximate circular symmetry in whole circle. It is necessary to add light material and steel pile, because they can effectively reduce the stress of concrete and prevent cracking.

Output Displacement Analysis of Symmetric Four-Bar Mechanism with Right Angle Flexible Hinge

in order to analyze the guide beam output displacement of the right-angle flexure hinge symmetrical four-bar mechanism, a half beam model was established based on the special structural characteristics and deformation characteristics. The formula of guiding displace were derived using approximate beam deflection curve equation. The finite element analysis of the model was carried out by ANSYS, it analyzed the cause of the theoretical value and simulation value for different reasons.

Numerical Analysis on Mechanical and Deformation Characteristics of Pile-Anchor Retaining Structure for Waterway Excavation

Mechanical and deformation characteristics of pile-anchor retaining structure was analyzed by using numerical simulation method. The rationality of numerical model was also verified through comparing measured data in field test and numerical results. On the basis of this numerical model, Mechanical and deformation characteristics of pile-anchor retaining structure under three different construction procedures were analyzed individually. The results show that: the maximum horizontal displacement of pile is controlled effectively by applying anchoring force, and the global horizontal displacement of pile increases as well. Forced state of pile is changed from being bended on one side to being bended on both sides, and maximum moment value decreases heavily. Therefore, anchor cable reinforcement should be arranged at the head of construction procedure of pile-anchor retaining structure. The later anchoring force be applied, the closer inflection point nears the pile top.

Study on the Seismic Performance of Shear Wall Structure with Unidirectional Wall Frames Based on Pushover Analysis

In the paper, the equation of stiff characteristic coefficient of shear wall structure with unidirectional wall frames was derived, the deformation characteristics of structure with different wall frames ratio and height were analyzed. Through pushover analysis, the seismic performance of structures were evaluated by interlayer displacement angle and plastic hinge development process. Under earthquake action, increase of wall frames ratio will make plastic deformation increase and maximum interlayer displacement floor move down.The bottom of structure is the weak region, the short wall limbs of wall frames are the weak structural vertical members. The research results show that the wall frames bring adverse effects on the structural seismic performance, so the different design meathods should be carried out according to the overturning moment proportion of wall frames.

Effect Analysis of Soil Improvement on Mechanical and Deformation Characteristics of Supporting Structure in Soft Area

Mechanical and deformation characteristics of pile-anchor retaining structure was analyzed by using numerical simulation method. The rationality of numerical model was also verified through comparing measured data in field test and numerical results. On the basis of this numerical model, Mechanical and deformation characteristics of supporting structure under the condition of different soil replacement ratio (m) was analyzed. The results show that: mechanical and deformation characteristics of supporting structure was improved by improving soil which behind retaining pile. The higher the soil replacement rate is, the effect to mechanical and deformation characteristics of supporting structure was more obvious.

Design method of pile-slab structure roadbed of ballastless track on soil subgrade

Pile-slab structure roadbed is a new form of ballastless track for high speed railway. Due to lack of corresponding design code, based on the analysis of its structure characteristics and application requirements, it is proposed to carry out load effect combination according to ultimate limit state and serviceability limit state, and the most unfavorable combination of each state is chosen to carry through design calculation for pile-slab structure. Space model of pile-slab structure can be simplified as a plane frame model, by using the orthogonal test method, and the design parameter of pile-slab structure is optimized. Moreover, based on the engineering background of Suining-Chongqing high-speed railway, the dynamic deformation characteristics of pile-slab structure roadbed are further researched by carrying on the indoor dynamic model test. The test results show that the settlement after construction of subgrade satisfies the requirement of settlement control to build ballastless track on soil subgrade for high-speed railway. Slab structure plays the role of arch shell as load is transmitted from slab to pile, and the vertical dynamic stress of subgrade soil is approximately of “K” form distribution with the depth. The distribution of pile stress is closely related to soil characteristics, which has an upset triangle shape where the large dynamic stress is at the top. Pile compared with soil shares most dynamic stress. Pile structure expands the depth of the dynamic response of subgrade and improves the stress of subgrade soil, and the speed of train has limited effect on dynamic response. These results can provide scientific basis for pile-slab structure roadbed used on soil subgrade.

Simulation for the Controlling Factors of Structural Deformation in the Southern Margin of the Junggar Basin

Abstract:According to the differences of structural deformation characteristics, the southern margin of the Junggar basin can be divided into two segments from east to west. Arcuate thrust‐and‐fold belts that protrude to the north are developed in the eastern segment. There are three rows of en echelon thrust‐and‐fold belts in the western segment. Thrust and fold structures of basement‐involved styles are developed in the first row, and décollement fold structures are formed from the second row to the third row. In order to study the factors controlling the deformation of structures, sand‐box experiments have been devised to simulate the evolution of plane and profile deformation. The planar simulation results indicate that the orthogonal compression coming from Bogeda Mountain and the oblique compression with an angle of 75° between the stress and the boundary originating from North Tianshan were responsible for the deformation differences between the eastern part and the western part. The Miquan‐Ürümqi fault in the basement is the pre‐existing condition for generating fragments from east to west. The profile simulation results show that the main factors controlling the deformation in the eastern part are related to the décollement of Jurassic coal beds alone, while those controlling the deformation in the western segment are related to both the Jurassic coal beds and the Eogene clay beds. The total amount of shortening from the Yaomoshan anticline to the Gumudi anticline in the eastern part is ∼19.57 km as estimated from the simulation results, and the shortening rate is about 36.46%; that from the Qingshuihe anticline to the Anjihai anticline in the western part is ∼22.01 km as estimated by the simulation results, with a shortening rate of about 32.48%. These estimated values obtained from the model results are very close to the values calculated by means of the balanced cross section.