Finite Element Analysis Program Research Articles

Simulation of Changes in Tensile Strain by Airbag Impact on Eyes After Trabeculectomy by Using Finite Element Analysis.

We studied the kinetic phenomenon of an airbag impact on eyes after trabeculectomy using finite element analysis (FEA), a computerized method for predicting how an object reacts to real-world physical effects and showing whether an object will break, to sequentially determine the responses at various airbag deployment velocities. A human eye model was used in the simulations using the FEA program PAM-GENERISTM (Nihon ESI, Tokyo, Japan). A half-thickness incised scleral flap was created on the limbus and the strength of its adhesion to the outer sclera was set at 30%, 50%, and 100%. The airbag was set to hit the surface of the post-trabeculectomy eye at various velocities in two directions: perpendicular to the corneal center or perpendicular to the scleral flap (30° gaze-down position), at initial velocities of 20, 30, 40, 50, and 60 m/s. When the airbag impacted at 20 m/s or 30 m/s, the strain on the cornea and sclera did not reach the mechanical threshold and globe rupture was not observed. Scleral flap lacerations were observed at 40 m/s or more in any eye position, and scleral rupture extending posteriorly from the scleral flap edge and rupture of the scleral flap resulting from extension of the corneal laceration through limbal damage were observed. Even in the case of 100% scleral flap adhesion strength, scleral flap rupture occurred at 50 m/s impact velocity in the 30° gaze-down position, whereas in eyes with 30% or 50% scleral flap adhesion strength, scleral rupture was observed at an impact velocity of 40 m/s or more in both eye positions. An airbag impact of ≥40 m/s might induce scleral flap rupture, indicating that current airbags may induce globe rupture in the eyes after trabeculectomy. The considerable damage caused by an airbag on the eyes of short-stature patients with glaucoma who have undergone trabeculectomy might indicate the necessity of ocular protection to avoid permanent eye damage.

Finite Elements Analysis and Topology Optimization of Parking Brake Lever and Ratchet

Topology optimization is known as one of the basic categories of structural optimization. Topology optimization is received increasing attention in many engineering disciplines. Topology optimization contributes to minimizing emissions and environmental effects by increasing material utilization efficiency and manufacturing sustainability. The mechanical parking brake is still used in many vehicles. This study aims to contribute to the reduction in vehicle weight by applying topology optimization. In addition, it also purposes to promote sustainability in manufacturing by reducing material usage and energy consumption. A CAD model was created by considering the existing mechanism element dimensions. The parking brake lever mechanism component was evaluated using topology optimization and finite element analysis methods. Static analyses were performed using a finite element analysis program. The results of this analysis were used as input data for topology optimization. In the topology optimization, the response constraint mass was increased by 5 increments from 50% to 95%. As a result, the maximum equivalent (von Mises) stress for the parking brake lever is 230,29 MPa, and for the ratchet is 11,559 MPa. The maximum total deformation value for the brake lever is 0,95853 mm and for the ratchet is 0,0079482 mm. The parking brake lever mass decreased by 18,48% from 0.27751 kg to 0.22622 kg. The ratchet mass decreased from 0.095042 kg to 0.061911 kg by 34.85%.

Numerical simulation of the 2010 4-story reinforced concrete structure tested on the E-defense shake table

Due to advancements in computational tools, performing a full nonlinear response history analysis of structures at the system level using detailed numerical simulations of components has become less demanding, even on standard personal computers. However, the modelling approaches need to be calibrated and verified against experimental measurements to ensure the accuracy of the system-level predictions. In this study, an advanced numerical simulation method is used to predict the 3D nonlinear dynamic response of a four-story reinforced concrete building tested at E-Defense shake table. The structure is modelled in the finite element analysis programme DIANA, using a previously developed and validated approach to predict the failure modes of doubly reinforced walls with confined boundary regions. Curved shell elements are used to model the walls and slabs, and the reinforcement is modelled using embedded bar elements. The frame elements are modelled using beam elements with the effect of confinement on the concrete behaviour represented in the material constitutive model. The numerical versus experimental response comparison is conducted at both local and global levels. For local levels, the base shear versus top displacement curves, strain gradients as well as the crack pattern predicted by the numerical model are compared with the test measurements. The inter-story drift response history is considered as the metric for the global level assessment. The effects of different modelling parameters on the accuracy of predictions are also investigated.

EXPERIMENTAL AND ANALYTICAL INVESTIGATION OF THE EFFECT OF LAYER NUMBER AND THICKNESS ON THE BENDING PROPERTIES OF GLULAM BEAMS

Wooden material is used in structural elements due to its many positive properties. Recent years have witnessed a surge in research directed toward enhancing the mechanical properties of wooden beams through the utilization of materials like steel plates and fiber reinforced polymers (FRP). Layered laminated timber, a composite material crafted from wood, serves as a testament to this endeavor. These laminated timbers constitute intricate engineering elements, fashioned from layers of wood characterized by distinct levels of strength and hardness, systematically arranged as per established guidelines. The present study is geared toward a comprehensive examination of the bending characteristics exhibited by glued beams, fashioned from spruce trees, encompassing six distinct sizes and varying layer counts. The manufacturing process yields beams with diverse cross-sectional profiles, including 3-layer and 7-layer variants. By performing 4-point bending tests of the beams, maximum load carrying capacity, bending strength, and elasticity modulus values were obtained experimentally. In addition to the experimental analyses, numerical models of the produced beams were created using the finite element analysis program, and static analyses were performed. In the experimental results, it was observed that the bending properties of the beams increased as the number and size of layers increased. It was determined that the maximum load carrying capacity, bending strength, and elasticity modulus values obtained as a result of experimental and numerical analysis were very close to each other. Numerical analysis results showed that beams produced with various number of layers and thicknesses can be simulated. It has been determined that the results obtained by creating numerical models instead of experimental analyses for this type of wooden beam may be sufficient.

Design and manufacturing process of pneumatic soft gripper for additive manufacturing

The soft gripper, constructed from elastic materials, serves as a crucial automated device component, aiming to minimize object damage. The central focus of utilizing soft grippers lies in their shape design, enabling effective handling of objects with low rigidity and diverse forms. This study delves into shape design research, employing a pneumatic pressure-responsive, tube-like soft gripper fabricated through injection molding. During the design phase, a comprehensive survey of soft gripper research trends was conducted, leading to two distinct configurations: Type1, drawing from established shapes, and Type2, a novel design ensuring bending angle stability. The primary dimensions of Soft Gripper Type 1 and Type 2 are as follows: lengths of 78.11 mm and 74.96 mm, heights of 18.69 mm and 20.0 mm, respectively, with a uniform thickness of 0.6 mm. The prediction of bending angles was accomplished through employment of the Abaqus finite element analysis program. In both simulation and experimentation, pneumatic pressures of 100, 200, and 300 kPa were applied to compare the bending angles of two types of soft grippers. While conventional injection molding remains a prevalent manufacturing technique, it confronts challenges like demolding and undercuts. Thus, for intricate shapes and monolithic soft grippers, layer-by-layer additive manufacturing emerges as a superior choice over injection molding. The implementation of this approach holds the potential for streamlined soft gripper design processes, potentially yielding reductions in both time and cost. The significance of these findings lies in advancing the capabilities of soft grippers, propelling them toward efficient and cost-effective applications in various fields.

Finite Element Analysis of Changes in Deformation of Intraocular Segments by Airbag Impact in Eyes of Various Axial Lengths.

We studied the kinetic phenomenon of an airbag impact on eyes with different axial lengths using finite element analysis (FEA) to sequentially determine the physical and mechanical responses of intraocular segments at various airbag deployment velocities. The human eye model we created was used in simulations with the FEA program PAM-GENERISTM. The airbag was set to impact eyes with axial lengths of 21.85 mm (hyperopia), 23.85 mm (emmetropia) and 25.85 mm (myopia), at initial velocities of 20, 30, 40, 50 and 60 m/s. The deformation rate was calculated as the ratio of the length of three segments, anterior chamber, lens and vitreous, to that at the baseline from 0.2 ms to 2.0 ms after the airbag impact. Deformation rate of the anterior chamber was greater than that of other segments, especially in the early phase, 0.2-0.4 ms after the impact (P < 0.001), and it reached its peak, 80%, at 0.8 ms. A higher deformation rate in the anterior chamber was found in hyperopia compared with other axial length eyes in the first half period, 0.2-0.8 ms, followed by the rate in emmetropia (P < 0.001). The lens deformation rate was low, its peak ranging from 40% to 75%, and exceeded that of the anterior chamber at 1.4 ms and 1.6 ms after the impact (P < 0.01). The vitreous deformation rate was lower throughout the simulation period than that of the other segments and ranged from a negative value (elongation) in the later phase. Airbag impact on the eyeball causes evident deformation, especially in the anterior chamber. The results obtained in this study, such as the time lag of the peak deformation between the anterior chamber and lens, suggest a clue to the pathophysiological mechanism of airbag ocular injury.

Three-dimensional creep calculation model for reliability analysis of concrete-filled steel tubular (CFST) structure

For long-span concrete-filled steel tube (CFST) structure, it is essential to implement efficient and realistic prediction models for the long-term processes of core concrete creep. In order to systematically study the main influential factors in CFST structure creep effects, a probabilistic analysis can be performed. The objective of this paper is to analyse the long-term response of CFST structure by using time-dependent reliability method. To address the problem of creep calculation, a novel and comprehensive presentation was developed. By converting the integral-type creep law to a differential-type form with internal variables, based on the Kelvin chain model, an elastic structural analysis with generally orthotropic elastic moduli and eigenstrains was established. We have compiled a three-dimensional (3-D) finite-element analysis programme that considers the creep Poisson effect of core concrete to analyse the long-term performance of the CFST structure. This is achieved by developing a commercial finite element code, such as Usermat in ANSYS. As calculation examples, several time-dependent analyses of a CFST stub column and long-span CFST arch bridge were performed. The calculated results of long-term behaviour agree well with experimental and measured data. Considering the randomness of various input parameters, such as physical dimensions and materials of the CFST structure, we have analysed the uncertainty using the Latin-hypercube-sampling (LHS) stochastic finite-element method. The results of creep sensitivity analysis revealed that coefficient of creep model uncertainty, steel and concrete elastic modulus were the three most influential parameters for CFST stub columns’ creep, and load, coefficient of creep model uncertainty, relative humidity, steel and concrete elastic modulus were the five for CFST arch bridges’ long-term deflection. In addition, the use of Monte Carlo (MC) and response surface (RS) methods for structural stochastic reliability analysis demonstrates the ability of these approaches to assess the reliability index of long-span CFST arch bridges. This provides a valuable reference for the design and performance evaluation of CFST structures.

Enhancing thermal efficiency of aluminum heat sink by reduced graphene oxide-layer coating approach

Light emitting diode (LED) technology plays a significant role in the market of lighting technologies due to its high efficiency compared to conventional lighting solutions. Cooling of high-power LEDs, on the other hand, is a critical aspect in maximizing LED performance. Furthermore, due to the powder, rain, and muds, LED armatures including a finned heat sink may not be efficient according to its design and utilization areas especially for outdoor illumination. Eliminating these factors, un-finned heat sink LED armatures are also preferred, yet the temperature dissipation of the un-finned type is not homogeneous relatively according to finned type. In this study, a graphene coated un-finned heat sink was developed to obtain relatively homogeneous temperature distribution and increase heat transfer of aluminum plate. An un-finned heat sink comprising thin graphene film was designed by a computer-aided-design (CAD) program and the thermal analysis was conducted by a finite element analysis (FEA) program. The experimental measurements offered that the maximum and minimum junction temperatures for the bare, and reduced graphene oxide (rGO)-layers coated aluminum heat sinks were obtained as 90 − 70◦C, and 59–54◦C, respectively. The outstanding in-plane thermal conductivity of rGO-layers facilitated the homogenous heat distribution throughout the aluminum heat sink. Moreover, the design and thermal analysis of developed heat sinks were validated with experimental results with the 2.4% error with respect to maximum junction temperature. It can be concluded that rGO-layers coated aluminum heat sink enabled to facilitated the heat transfer more than bare aluminum due to its higher thermal conductivity. In brief, this work opens a new gate for designing the graphene based materials-integrated cooling solution for LED applications.

The Effect Of Pre-Forming On The Forged Part In the Hot Forging Process

Analysis programs based on finite elements have great importance in verifying the design and production processes. In the automotive industry, many parts are produced by hot forging process. The die designs of the parts to be produced by hot forging process are verified by finite element analysis programs. In this study, the importance of pre-forming in hot forging process is investigated by using finite element method and the necessity of pre-forming is indicated by the analysis. In the analysis phase of the study, hot forging finite element analysis was performed for 4 different cases of the torque rod housing that one of the suspension parts of heavy commercial vehicles part using FORGE NxT program. In addition, experimental studies were carried out for these cases and the results obtained were compared with the analysis results. The results obtained as a result of the analysis and experimental study were found to be consistent with each other. It has been observed that pre-forming is very important and necessary in the hot forging process in order to increase die life and to reduce die runaway, crease and non-filling problems.

INVESTIGATION OF THE AUXETIC BEHAVIOR OF AN ORIGINAL LATTICE STRUCTURE DESIGN

Auxetic structures are special structures with negative Poisson's ratio due to their geometric shapes in their internal structure. When tensile force is applied to these structures, transverse and longitudinal expansions are observed, while transverse and longitudinal contractions are observed when compressive force is applied. There are many different unit cell designs such as chiral, arrowhead, re-entrant in auxetic structures. In this study, a unique cell design was studied and the behavior of an auxetic lattice structure was investigated. The lattice structure designed with different geometric thicknesses and different matrices was analyzed with the finite element analysis program and found to have a negative Poisson's ratio. In the designed lattice structure, the structure with 4×4 matrix and 3 mm geometric thickness was found to have the best negative Poisson's ratio.

A modal-based method for blast-induced damage assessment of reinforced concrete columns: Numerical and experimental validation

Reinforced concrete (RC) columns play a crucial role in the overall performance of modern RC frame buildings under blast loading. The RC columns under blast loads might experience various irreversible consequences such as concrete cracks, crushing and spalling, changing the status of both modal properties and load-carrying capacity. In this paper, the blast-induced damage assessment of the RC columns involving the measurement of modal parameters was introduced and validated. Firstly, a modal-based method for blast-induced damage assessment of RC columns was proposed, in which the damage is characterized as the reduction of axial bearing capacity and further expressed as the explicit function of the vibration frequencies and the mass-normalized displacement mode shapes. Then, the finite-element analysis program LS-DYNA was employed to establish the numerical model of RC columns under axial compression loads and lateral blast loads. The residual load-bearing capacities and modal properties of the RC columns were illustrated. By using the numerical results collected in the present study, the validity of the proposed damage assessment method was discussed and proved numerically. Further, field explosion tests and experimental modal tests were conducted, and the results showed that the modal-based damage assessment method exhibited remarkable agreement with the blast damage determined by residual bearing capacities. Based on the numerical and experimental results, the proposed modal-based damage assessment method is applicable for the non-destructive evaluation of blast-induced damage of RC columns.

Themomechanical Response of an Additively Manufactured Hybrid Alloy by Means of Powder Bed Fusion

The laser powder bed fusion (L-PBF) technique was utilized to manufacture a hybrid M789-N709 alloy by depositing M789 steel on wrought N709 steel. The tensile strength of the M789-N709 interface generated during the process has been established to be higher than that of the base materials. In the previous work of the current authors, extensive characterization of the M789-N709 interface (before and after heat treatment) was performed by means of electron backscatter diffraction, electron probe microanalysis, transmission electron microscopy with energy dispersive spectroscopy, and atom probe tomography analyses, to understand the mechanisms associated with its superior strength. In the present work, since the application of the hybrid alloy is targeted towards an elevated temperature environment, the individual high-temperature mechanical properties of M789 and N709 steels were acquired at various temperatures and strain rates using a Gleeble 563 thermomechanical system. Then, based on the flow curves, phenomenological-, and physical-based constitutive material models were established. These constitutive models can be utilized to accurately assess the high-temperature response of the hybrid alloy system using finite element analysis programs. This work demonstrates the application of thermomechanical processing and constitutive modeling in the field of metal additive manufacturing.

Optimization of Free Vibration for Sandwich Foam Core

The structural dynamic features of a sandwich foam core structure with core and surface thicknesses are examined to increase the structure's resistance to vibration. The thickness of the core and surface of the sandwich foam core structure are defined as design variables in the optimization function of natural frequency parameters. The finite element analysis program FEA software was used for the analyses. The multi-objective optimization problem using RMS. The derived natural frequencies are compared with the outcomes of the experiments to validate the numerical model. The calculated natural frequencies are compared with the outcomes of the experiments to validate the numerical model. The structural optimization is then completed, using a sandwich foam core structure. The results show that the Aluminium Layer and foam core Thicknesses (m) are 0.0086 and 0,0357 m respectively

Understanding the Effect of Seasonal Climate Variability on the Salinity in Unsaturated Agricultural Soil

Salinization/desalinization processes in the soil vadose zone are important to define agricultural irrigation and drainage schedules, especially in reclaimed crop areas. Numerical modeling of soil–climate interaction is a very helpful tool to understand soil salinity distribution and solute transport and therefore define efficient desalination solutions. A finite element analysis program Code_Bright was used to perform a coupled thermo-chemo-hydraulic analysis aiming at investigating the effect of climate actions on the distribution of soil salinity in depth, by modeling solute transport in the vadose zone under fresh/saline groundwater supply. The analysis separated first the effect of rain infiltration and evaporation, and then a real climate was considered as the boundary condition. A downward flow pattern induced by rainfall in the unsaturated zone resulted in a nonlinear salt leaching process. Significant differences in salt concentration between the surface and lower layer caused by rainfall resulted in a decrement in the leaching efficiency. Evaporation causes water to move upward and salt transport to the surface, thus enhancing the soil salinity above the evaporation front. The salinity above the groundwater table and below the evaporation front were less affected regardless of the salinity of the supplied groundwater. The model simulated the salt leaching process during the wet seasons and salt accumulation processes during the dry ones. The soil salinity and saturation at the soil surface have significantly responded to seasonal climate variability. A typical seasonal climate variability would result in a low salt leaching efficiency through years in the coastal reclamation area. These results would be helpful for the design of soil salinization management strategies, such as reducing salt accumulation by reducing evaporation or leaching the surface salt in the dry season, and increasing the drainage to promote leaching in the wet season.

Numerical Investigation of the Evolving Inelastic Deformation Path of a Solder Ball Joint under Various Loading Conditions

Solder joints of ball grid arrays (BGA) have been widely used to connect electronic components to printed circuit boards (PCBs) and are often subjected to mechanical stress. Several studies have been conducted on the mechanical reliability of solder joints. While these studies have been useful in the industry, detailed studies on how the inelastic deformation path of the solder ball joints evolves under specific loading conditions have not been sufficiently reported. This study aims to understand how the inelastic deformation path evolves when a solder joint is subjected to a constant external force by utilizing the theory of mechanics. It has also been found that the mechanical failure is strongly influenced by the evolution history of the deformation modes in materials. For this study, an elastoplastic constitutive model and a ductile fracture criterion were implemented into the vectorized user-defined material (VUMAT) subroutine of the ABAQUS program for finite element (FE) analysis. With the model, the evolution of the inelastic deformation path of a single solder ball under different loading conditions was numerically analyzed. Three loadings (shear, compression, and bending) were chosen as the basic loading conditions. In addition, combinations of the basic loadings resulted in three dual loadings and one complex loading. The simulation results showed that the shear and bending caused the fracture for both single and dual loadings, but when combined with compression, the fracture was suppressed. The results indicate that fracture is not solely determined by the magnitude of equivalent plastic strain but also by the evolution of inelastic deformation mode. This research offers an improved understanding of the significance of the inelastic deformation path and fracture.

Stress Distribution Prediction of Circular Hollow Section Tube in Flexible High-Neck Flange Joints Based on the Hybrid Machine Learning Model.

The flexible high-neck flange is connected to the circular hollow section (CHS) tube through welding, and the placement of the weld seam and corresponding stress concentration factor (SCF) are crucial determinants of the joint's fatigue performance. In this study, three hybrid models combining ant colony optimization (ACO), a genetic algorithm (GA), and grey wolf optimization (GWO) with a random forest (RF) model were developed to predict the stress distribution on the inner and outer walls of the CHS tube under different flange parameter combinations. To achieve this, an automated finite element (FE) analysis program for flexible high-neck flange joints was initially developed based on ABAQUS 2020 software. Parameter combinations were randomly selected within a reasonable range to simulate the nonlinear mechanical behavior of the joint under uniform tension, generating a dataset comprising 5417 sets of data. The accuracy of the FE model was validated through experimental data from the literature. Based on this, feature importance analysis was conducted to reveal the influence of different variable parameters on the stress distribution in the tube of the joint. The flange parameters and tube stress distribution are considered as inputs and outputs, respectively. Three hybrid RF models, specifically ant colony optimization-based random forest (ACO-RF), genetic algorithm-based random forest (GA-RF), and grey wolf optimization-based random forest (GWO-RF), are trained for regression prediction. The results demonstrate that the three hybrid models outperform the original machine learning model in predictive accuracy. The ACO-RF model achieved the highest accuracy with average coefficients of determination (Rmean2) of 0.9983 and 0.9865 on the testing and training sets, respectively. Building upon this foundation, the study developed a corresponding open-source graphical user interface (GUI) as a tool for facilitating computations and visualizing results. Finally, a case study on fatigue damage assessment of a flexible high-neck flange joint in a wind-turbine tower is presented to demonstrate the application of the proposed model in this study.

A new approach for analysing motion and deformation of left ventricle: Post‐processing 3D echocardiography data with finite element method

AbstractIn the medical community, it is common practice to examine segmental (regional) values. For instance, echocardiography data are analysed by dividing the left ventricle (LV) endocardial surface into 16 or 17 areas (segments), which actually consist of several nodes (vortices) and the nodal values are averaged over the segments. Although, the averaged segment values provide useful information and are widely used, looking at pointwise values might enable a more extensive LV assessment, which has not been attempted so far. For instance, averaging might be ruling out some unusual localized deformations, which can be only detected through a pointwise distribution. Therefore, in this contribution, we introduce a new methodology to analyse 3D echocardiography data from computational modelling perspective which eventually enables a pointwise distribution of deformation related quantities over the LV endocardial surface. To this end, we export the tracked LV endocardial surface from a dedicated software 4D LV‐analysis Tomtec, which enables to export the current coordinates of the nodes on the surface. The coordinates are then integrated into a finite element analysis program and, eventually, one can compute any deformation related quantity and obtain a pointwise distribution over the endocardial surface. To our best knowledge, such an approach has not been introduced before. In order to demonstrate the usability, we compare the pointwise value distribution to traditional averaged segmental values. Additionally, we calculate the stress distribution and the sphericity index in a pointwise manner, which are not provided by commercial LV analysis softwares.

Flexural behavior of steel fiber reinforced concrete beams comprising coarse and fine rubber and strengthened by CFRP sheets

Despite having many advantages, using rubber to produce reinforced concrete members like beams is still restricted. When there is more waste tire rubber in concrete structures, rubber concrete's flexural and compressive strengths gradually decrease. However, this study used steel fibers to improve compressive strength and externally bonded carbon fiber-reinforced polymer (CFRP) sheets to increase flexural strength. Four groups of three reinforced concrete beams each were established for the study's use. The first and third groups of concrete beams used a volumetric replacement of fine and coarse aggregates with 5% and 10% waste tire rubber. However, steel fibers were added to the second and third groups at a rate of 1.25% of the concrete volume. Waste tire rubber and steel fibers were not replaced or added to the fourth group, the main reference group. The dimensions of each beam were 2.1×0.2×0.3 m. A concrete beam's first member is always free of external reinforcement, followed by its second member, which has one layer, and its third member, which has two layers of CFRP sheet. ABAQUS, a finite element analysis program, was used numerically to represent the third strengthening layer. The results showed that strengthening the reinforced rubberized concrete beams with a single layer of CFRP sheets increased the load at first crack and failure by 8.57% and 17.64%, respectively, compared to the unreinforced reference beam, compensating for the loss caused by the production of rubberized concrete and adding additional flexural strength. These loads increased by 31.43% and 26.45%, respectively, due to the steel fibers added to the beams containing these waste tire rubber. Strengthening with two layers of CFRP sheets increased the load at first crack and failure by 17.14 and 34.27, respectively. The steel fibers added to the beams that contained these amounts of waste tire rubber, on the other hand, caused these loads to increase by 42.86 and 49.23%, respectively. Strengthening with three layers numerically results in an exponential increase in load at the first crack and the failure by 8.03 and 52.88%, respectively. On the other hand, the loads on the beams that contained these quantities of waste tire rubber increased by 50.49% and 104.47%, respectively, when steel fibers were added to them.

A STUDY OF SUBSURFACE OUTFLOW OF PERMEABLE FRICTION COURSE PAVEMENT BASED ON FINITE ELEMENT ANALYSIS

Permeable friction course pavement is designed with high porosity so that water can infiltrate into its pores and drain out laterally through the side. This study observes the subsurface outflow of a permeable friction course pavement via the finite element analysis program SV Flux 2D. A series of analyses were conducted for the permeable friction course pavement with different slope and rainfall intensity values. The results showed that different slope values provided different results for the subsurface outflow. As the slope increased, the subsurface outflow of the permeable friction course pavement increased. It is noticed that the effect of slope on the subsurface outflow decreased when the slope increased from 6% to 8%. In addition, this study also found that as the time of rain events increased, the subsurface outflow pavement was reduced. The investigation of the effect of rainfall intensity on the subsurface outflow of the permeable friction course pavement showed that as the rainfall intensity increased, the subsurface outflow steadily increased. However, it is noted that at the higher rainfall intensity, the pavement became saturated faster and the overflow happened earlier. In the future, further studies focused on the drainage of permeable friction course pavement including subsurface and surface outflow should be carried out.

Efficient numerical simulation of steel-UHPC composite structures based on a fiber beam-column model

To satisfy the demands of different engineering scenarios, ultra-high performance concrete (UHPC) is usually combined with steel to form various steel-UHPC composite structures. This study proposes an efficient numerical method for simulating steel-UHPC composite structures. A finite element analysis program, SU-COMPONA, is developed, which combines the fiber beam-column model and the concept of smeared cracks. Rational material constitutive laws are proposed and integrated into the program to describe the uniaxial behavior of UHPC and steel fibers. The proposed numerical method is validated against sufficient experimental data for various steel-UHPC composite structures, including reinforced UHPC beams and slabs, steel-UHPC composite beams and slabs and steel-UHPC-steel sandwich beams. In addition, the simulation performance is evaluated quantitatively. The results show that the proposed method can predict the ultimate capacity, the load-deflection curve and the development of crack widths with satisfactory accuracy and stability. Compared with the elaborate three-dimensional finite element method, the proposed method based on the fiber beam-column model is a competitive numerical approach that can achieve higher efficiency with slightly less accuracy.