• Smart Structures and Systems
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• v.24 no.4
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• pp.427-434
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• 2019

This study investigates the structural integrity of the amphibious tour bus under the rollover condition. The multi-purpose bus called Dual Mode Tour Bus (DMTB) which explores on land and water has been designed on top of a truck platform. Prior to the fabrication of new upper body and sailing equipment of DMTB, computational analysis investigates the rollover protection of the proposed structure including superstructure, wheels, and axles. The Computer-Aided Design (CAD) of the whole vehicle model is meshed and preprocessed under high performance using the Altair HyperMesh to attain the best mesh model suited for finite element analysis (FEA) on the proposed system. Meanwhile, the numerical model is analyzed by employing LS-DYNA to evaluate the superstructure strength. The numerical model includes detail information about the microstructure and considers wheels and axles as rigid bodies but excludes window glasses, seats, and interior parts. Based on the simulation analysis and proper modifications especially on the rear portion of the bus, the local stiffness significantly increased. The vehicle is rotated to the contact point on the ground based on the mathematical method presented in this study to save computational cost. The results show that the proposed method of rollover analysis is highly significant not only in bus rollover tests but in crashworthiness studies for other application. The critical impartments in our suggested dual-purpose bus accepted and passed "Economic Commission for Europe (ECE) R66".

• Journal of the Korean Society of Safety
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• v.34 no.5
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• pp.1-6
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• 2019

The mobile elevated work platforms(MEWPs) consist of work platform, extending structure, and car, and it is a facility to move persons to working positions. MEWPs are useful but composed complex pieces of equipments, and accidents are caused by equipment defects. Among them, accidents caused by fracture of the bolts fixing the extension structure and the turntable are increasing. In this study, fatigue failure and fatigue life of a turntable fixing bolt subjected to irregular fatigue load were analyzed by FEA. For this purpose, finite element modeling is proposed and structural analysis and fatigue analysis are performed simultaneously for fixing bolts. As a result of the structural analysis, it was confirmed that there is no risk of permanent deformation because the maximum stress acting on the fixing bolt is lower than the yield strength, and fatigue analysis was confirmed that the fatigue life is less than the design standard. The fatigue analysis results of this study can be effectively used for the design and the documentary assessment of the safety certification of the MEWPs by examining the fatigue life of the turntable fixing bolt.

• Smart Structures and Systems
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• v.7 no.5
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• pp.417-432
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• 2011

The present paper is devoted to vibration canceling and shape control of piezoelastic slender beams. Taking into account the presence of electric networks, an extended electromechanically coupled Bernoulli-Euler beam theory for passive piezoelectric composite structures is shortly introduced in the first part of our contribution. The second part of the paper deals with the concept of passive shape control of beams using shaped piezoelectric layers and tuned inductive networks. It is shown that an impedance matching and a shaping condition must be fulfilled in order to perfectly cancel vibrations due to an arbitrary harmonic load for a specific frequency. As a main result of the present paper, the correctness of the theory of passive shape control is demonstrated for a harmonically excited piezoelelastic cantilever by a finite element calculation based on one-dimensional Bernoulli-Euler beam elements, as well as by the commercial finite element code of ANSYS using three-dimensional solid elements. Finally, an outlook for the practical importance of the passive shape control concept is given: It is shown that harmonic vibrations of a beam with properly shaped layers according to the presented passive shape control theory, which are attached to an resistor-inductive circuit (RL-circuit), can be significantly reduced over a large frequency range compared to a beam with uniformly distributed piezoelectric layers.

• Computers and Concrete
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• v.7 no.2
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• pp.159-167
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• 2010

This paper demonstrates numerical techniques for complex large-scale modeling with microplane constitutive theories for reinforced high strength concrete, which for these applications, is defined to be around the 7000 psi (48 MPa) strength as frequently found in protective structural design. Applications involve highly impulsive loads, such as an explosive detonation or impact-penetration event. These capabilities were implemented into the authors' finite element code, ParaAble and the PRONTO 3D code from Sandia National Laboratories. All materials are explicitly modeled with eight-noded hexahedral elements. The concrete is modeled with a microplane constitutive theory, the reinforcing steel is modeled with the Johnson-Cook model, and the high explosive material is modeled with a JWL equation of state and a programmed burn model. Damage evolution, which can be used for erosion of elements and/or for post-analysis examination of damage, is extracted from the microplane predictions and computed by a modified Holmquist-Johnson-Cook approach that relates damage to levels of inelastic strain increment and pressure. Computation is performed with MPI on parallel processors. Several practical analyses demonstrate that large-scale analyses of this type can be reasonably run on large parallel computing systems.

• Structural Engineering and Mechanics
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• v.47 no.1
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• pp.1-25
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• 2013

A combined thermal and mechanical action in roller compacted concrete (RCC) dam analysis is carried out using a three-dimensional finite element method. In this work a numerical procedure for the simulation of construction process and service life of RCC dams is presented. It takes into account the more relevant features of the behavior of concrete such as hydration, ageing and creep. A viscoelastic model, including ageing effects and thermal dependent properties is adopted for the concrete. The different isothermal temperature influence on creep and elastic modulus is taken into account by the maturity concept, and the influence of the change of temperature on creep is considered by introducing a transient thermal creep term. Crack index is used to assess the risk of occurrence of crack either at short or long term. This study demonstrates that, the increase of the elastic modulus has been accelerated due to the high temperature of hydration at the initial stage, and consequently stresses are increased.

• Steel and Composite Structures
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• v.39 no.2
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• pp.171-188
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• 2021

Plastic deformation of link beams in eccentrically braced frames is the primary dissipating source of seismic energy. Despite the excellent compatibility with the architectural designs, previous researches indicate the deficiency of flexural yielding links compared to the shear yielding ones because of their localized plastic deformation. Previous investigations have shown that implementing web openings in beams could be an efficient method to improve the seismic performance of moment-resisting connections. Accordingly, this research investigates the use of flexural links with stiffened and un-stiffened web openings to eliminate localized plasticity at the ends of the link. For this purpose, the numerical models are generated in finite element software "Abaqus" and verified against experimental data gathered from other studies. Models are subjected to cyclic displacement history to evaluate their behavior. Failure of the numerical models under cyclic loading is simulated using a micromechanical based damage model known as Cyclic Void Growth Model (CVGM). The elastic stiffness and the strength-based and CVGM-based inelastic rotation capacity of the links are compared to evaluate the studied models' seismic response. The results of this investigation indicate that some of the flexural links with edge stiffened web openings show increased inelastic rotation capacity compared to an un-perforated link.

• Steel and Composite Structures
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• v.30 no.3
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• pp.231-251
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• 2019

In the present study, a numerical and experimental investigation has been carried out on the seismic behavior of RC columns of a bridge which damaged under corrosive environments and retrofitted by various techniques including combined application of CFRP sheets and steel profiles. A novel hybrid retrofitting procedure, including the application of inner steel profiles and outer peripheral CFRP sheets, has been proposed for strengthening purpose. Seven large-scale RC columns of a Girder Bridge have been tested in the laboratory under the influence of simultaneous application of constant axial load and the lateral cyclic displacements. Having verified the finite element modeling, using ABAQUS software, the effects of important parameters such as the corrosion percentage of steel rebars and the number of CFRP layers have been evaluated. Based on the results, retrofitting of RC columns of the bridge with the proposed technique was effective in improving some measures of structural performance such as lateral strength degradation and higher energy absorption capability. However, the displacement ductility was not considerably improved whereas the elastic stiffness of the specimens has been increased.

• Wind and Structures
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• v.29 no.3
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• pp.177-194
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• 2019

While establishing adequate load paths in the light-frame wood structures is critical to maintain the overall structural integrity and avoid significant damage under extreme wind events, the understanding of the load paths is limited by the high redundant nature of this building type. The objective of the current study is to evaluate the system effects and investigate the load paths in the wood structures especially the older buildings for a better performance assessment of the existing building stock under high winds, which will provide guidance for building constructions in the future. This is done by developing building models with configurations that are suspicious to induce failure per post damage reconnaissance. The effect of each configuration to the structural integrity is evaluated by the first failure wind speed, amajor indicator beyond the linear to the nonlinear range. A 3D finite-element (FE) building model is adopted as a control case that is modeled using a validated methodology in a highly-detailed fashion where the nonlinearity of connections is explicitly simulated. This model is then altered systematically to analyze the effects of configuration variations in the model such as the gable end sheathing continuity and the gable end truss stiffness, etc. The resolution of the wind loads from scaled wind tunnel tests is also discussed by comparing the effects to wind loads derived from large-scale wind tests.

• Journal of IKEEE
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• v.23 no.3
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• pp.793-799
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• 2019

In this study, the diffusion process and the thermal energy distribution gradient of the sensor were confirmed by using the finite element analysis program (COMSOL) of the mesh method to analyze the thermal diffusion in the wearable fabric (Nylon) + MWCNT gas sensor. To analyze the diffusion process of thermal energy, the structure of the gas sensor was modeled in a two dimension plane. The proposed modeling was presented with the characteristic value for the component of the sensor, and the gas sensor designed using the mesh finite element method (FEM) was proposed and analyzed by suggesting the one-way partial differential equation in the governing equation to know the degree of thermal energy diffusion and the thermal energy gradient. In addition, the temperature gradient 10[K/mm] of the anode-cathode electrode layer and the gas detection unit was investigated by suggesting the heat velocity transfer equation.

• The Journal of the Convergence on Culture Technology
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• v.5 no.2
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• pp.355-360
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• 2019

In this study, the structural stability of the railway level crossing system using rubber panel for high speed lines was investigated by applying the specification for wind load conditions (Train gust) of high speed train (300km/h and 360km/h). A finite element analysis using three-dimensional modeling was carried out by applying the field conditions that was installed with the complicated configuration of the rubber plate panel system. As a result of this study, the structural stability of the rubber plate panel system for high speed train gust was analytically verified.