Rectangular Wall Research Articles

Optimal Design of Shear Wall Sections Considering Different Stress-Strain Relationships of Steel According to Eurocode 2

The present paper highlights the usefulness of bi-linear stress strain relationship of steel with inclined plastic branch with respect to horizontal plastic branch for slender rectangular shear wall design. The inclined branch refers to strain hardening of steel for which, stresses also increase with strain beyond the yield point. This significantly complicates the solution process for load-based design approach as adopted in flexure design. For design of sections subjected to axial forces with flexure, capacity-based approach of design is adopted instead of load-based design. Hence, the myth that the inclined plastic planch will lead to cumbersome and tedious calculations does not seems to hold good for capacity-based design approach which is adopted for design of columns and shear walls. In the present paper using different strength classes of concrete as permitted by the latest version of Eurocode2 (2023) and strength of steel, fyk= 500 MPa along with different ductility classes have been used for the development of P-M interaction charts for rectangular shear walls with uniformly distributed vertical reinforcements. An average of 12.26% and 3.42% increment in moment capacity values have been obtained in under reinforced and over reinforced failure conditions respectively between charts prepared by inclined and horizontal plastic branch.

Construction Brick Production Industry in Southern Thailand: a Case Study of Kiln

Purpose: To study the kiln that affect the construction brick production industry and to provide guidelines for solving problems. Method: This is qualitative research collecting data from 17 Kiln brick production industry Owners with in-depth interview. Data is analyzed by content and thematic analysis. Results and Conclusion: (1) Physical characteristics of the furnace square brick kiln model. The structure of this kiln is made of cooked bricks into a rectangular permanent wall. There is a firewood compartment and a brick entry door on the side. Production capacity is 50,000-100,000 bricks/stove. Specific energy was 1.6-3.8 MJ/kg of brick, some stoves use 7.8 MJ/kg brick. (2) Burning temperature. Brick firing in Thailand usually ends at 900 degrees Celsius, with brick heating, brick drying, brick kilning, and temperature reduction. which uses a fairly high temperature for burning. (3) The burning time is approximately 7 days, which corresponds to the temperature of the firing side by heating the bricks, baking the bricks, burning the bricks, and reducing the temperature. By using firewood as a leaven. Therefore, there is a lack of technology development in brick production and efficient brick firing with a long firing period. (4) Heat energy loss. Brick firing in Thailand usually ends at a temperature of 900 degrees Celsius and is then turned off for a few days. To reduce cracking due to sudden temperature changes, then turn on the kiln to let the bricks cool naturally allowing the bricks to cool naturally. The heat energy stored is left and that is a loss of heat energy. Research Implications: Brick burning uses a lot of energy, firewood as fuel, and the efficiency of the kilns used is quite low. It is likely that the efficiency of brick kilns will be improved or brick kilns with high thermal efficiency to be used as a replacement to achieve high efficiency. This allows the brick production industry to continue to exist. Originality/Value: The improvement of fuel using for Kiln in brick burning can be improved for more effectiveness and clean environment.

A Cell Pre-Wrapping Seeding Technique for Hydrogel-Based Tubular Organ-On-A-Chip.

Organ-on-a-chip (OOC) models based on microfluidic technology are increasingly used to obtain mechanistic insight into (patho)physiological processes in humans, and they hold great promise for application in drug development and regenerative medicine. Despite significant progress in OOC development, several limitations of conventional microfluidic devices pose challenges. First, most microfluidic systems have rectangular cross sections and flat walls, and therefore tubular/ curved structures, like blood vessels and nephrons, are not well represented. Second, polymers used as base materials for microfluidic devices are much stiffer than in vivo extracellular matrix (ECM). Finally, in current cell seeding methods, challenges exist regarding precise control over cell seeding location, unreachable spaces due to flow resistances, and restricted dimensions/geometries. To address these limitations, an alternative cell seeding technique and a corresponding workflow is introduced to create circular cross-sectioned tubular OOC models by pre-wrapping cells around sacrificial fiber templates. As a proof of concept, a perfusable renal proximal tubule-on-a-chip is demonstrated with a diameter as small as 50µm, cellular tubular structures with branches and curvature, and a preliminary vascular-renal tubule interaction model. The cell pre-wrapping seeding technique promises to enable the construction of diverse physiological/pathological models, providing tubular OOC systems for mechanistic investigations and drug development.

Effect of flexible membrane in triaxial test on the mechanical behaviour of rockfill material using Discrete Element Method

The investigation of rockfill materials poses challenges due to their large particle size, associated high cost, and long laboratory testing duration. As a result, empirical correlations based on historical experimental studies are commonly used to design and analyse rockfill structures. However, the extensive use of rockfill in a wide range of applications and limited understanding of its mechanical behaviour emphasize the need for further research. These make it necessary to develop a robust technique capable of capturing key parameters such as particle shape and breakage, allowing for the simulation and study of large-scale assemblies with realistic boundary conditions. Given that the behaviour of rockfill is highly scale-dependent, primarily due to particle breakage, the simplified laboratory tests on the scaled-down assemblies can be misleading. Particle breakage is a fundamental phenomenon in the mechanical behaviour of rockfill and significantly affects shear strength, deformability, and porosity under different stress levels. The particle breakage is influenced by factors such as the rockfill’s maximum particle size, mineralogy, particle shape, gradation, and confining stresses. This study adopts a computationally efficient breakage method called the Modified Particle Replacement Method (MPRM) based on the Discrete Element Method. A Tile-Based Flexible Membrane (TBFM) for triaxial test modelling has been developed by employing segmental rectangular walls to create a deformable membrane. The effects of critical parameters, including particle shape, confining stress, membrane resolution, degree of flexibility, and the characteristic strength of the particles, are examined. The findings of the combined MPRM-TBFM approach demonstrate the significant influence of membrane flexibility on volumetric-related behaviour.Graphical

Seismic Damage and Behavior Assessment of Drift-Hardening Concrete Walls Reinforced by LBUHS Bars.

This paper experimentally and analytically investigated the damage and seismic behavior of concrete walls reinforced by low-bond ultra-high-strength (LBUHS) bars. To this end, four half-scale rectangular concrete walls were fabricated and tested under reversed cyclic loading and constant axial compression. The test variables were the shear span ratio and the axial load ratio. Based on the test results, the propagation of cracks on the wall surface, the maximum strain capacity of concrete, the hysteresis loops and envelope curves, the residual drifts, and the strain distributions of LBUHS rebars were presented and discussed. The experimental results showed that all the test walls could exhibit drift-hardening capability until at least a 2.0% drift ratio if LBUHS rebars were anchored by nuts at their ends. The test results also indicated that the maximum strain capacity of concrete was above 0.86%, much larger than the currently recommended 0.4%. After unloading from the transient drift ratios of 2.0% and 2.5% for the walls with shear span ratios of 1.5 and 2.0, respectively, the measured residual drift ratios were controlled below 0.4%, which is less than the critical drift ratio (0.5%) having 98% repairable probability recommended in the FEMA document (P-58) for general concrete structures. Furthermore, a numerical method was presented to evaluate the cyclic response of the test walls, and a comparison between the experimental and the calculated results verified the reliability and accuracy of the proposed numerical method.

Design and hydrodynamic study of a new pile-based breakwater-OWC device combined system

In order to enhance the conversion efficiency and optimize the hydrodynamic performance of the OWC device, a novel combined system composed of a pile-based OWC chamber and a perforated wave-eliminator is proposed. The schemes with rectangular front wall M1, elliptical front wall M2, M3 are designed. Physical tests and numerical simulations were conducted for the hydrodynamic process under the action of wave of the system with H/d = 0.16, 0.20, 0.24 and L/B = 3.3, 3.8, 4.3, 4.7, 5.2, 5.5, 6.4. The obtained-results show that the system has better energy converting and wave eliminating performance than the other existing systems. Its maximum conversion efficiency ξ is up to 70%, while its transmission coefficient Ct is less than 0.45. Compared to M1 and M2, M3 can improve the efficiency ξ of the system (up to approximately 35%) and reduce the maximum force exerted on the system (up to 10%). When studying the forces on the combined system, the horizontal force (in the direction of wave propagation) can be primarily calculated by considering the force exerted on the chamber. However, when investigating the vertical forces (opposite to gravity) acting on the system, both the OWC chamber and the wave-eliminator need to be considered. The research results can provide valuable references for further design optimization of OWC devices.

Acoustic performance evaluation of railway boundary walls using a computational fluid dynamics-based simulation approach.

Railway noise has become a significant concern for trackside residents due to increased volume of high-speed passenger and freight train traffic. To address this, active measures, such as reducing noise at the source, and passive measures, such as installing noise barriers along the transmission path, are widely being used. In urban areas, railway boundary walls are constructed to prevent encroachments of railway lands and to avoid pedestrian trespassing of railway tracks. This study aims to evaluate the effectiveness of such a boundary wall for reducing noise and proposes an improved alternative through computational fluid dynamics (CFD) simulations. Various noise barriers with different geometry, shape, and surface materials were simulated and validated with the field conditions based on a rectangular wall of height 2.75 m. Noise attenuation was evaluated by measuring railway noise spectra at different positions, including 0.5 m in front and behind the barrier and at the facade of the residential area. The insertion loss based on field measurements for a rectangular barrier of height 2.75 m was observed to be 5.2 dBA. The simulation results indicated a positive correlation between barrier height and insertion loss, with a maximum attenuation of 17 dBA achieved with a barrier of height 6 m. The most effective noise barrier for reducing railway noise was a T-shaped barrier with a height of 6 m and a projection length of 2 m, with an insertion loss of 22 dBA. This study recommends constructing the barrier with soft materials on its surface to reflect and absorb sound waves effectively. These findings have potential implications for urban planners and policymakers in designing effective noise barriers in residential areas near railway lines.

Sectional response of non-rectangular concrete walls with minimum vertical reinforcement

Past research that investigated the behaviour of rectangular lightly reinforced concrete walls resulted in revisions to minimum vertical reinforcement provisions in concrete design standards in both New Zealand (NZS 3101:2006) and the United States (ACI 318-19). However, the minimum vertical reinforcement provisions developed for rectangular wall sections may not be suitable for non-rectangular walls due to the influence of flanges on the nominal flexural and cracking section capacities. A parametric study confirmed that non-rectangular wall sections with minimum vertical reinforcement in accordance with current NZS 3101 design provisions exhibit a lower margin between cracking and nominal flexural strength than comparable rectangular wall sections. The ratio of the sectional nominal flexural strength to cracking strength (Mn/Mcr ) was less than 1.0 for non-rectangular sections with long flange lengths and low axial loads. The model results indicated that current vertical reinforcement requirements are insufficient to prevent a sudden and potentially unstable strength drop when cracking occurs in non-rectangular walls. A theoretical equation to calculate the required minimum vertical reinforcement was proposed for the typical I-shaped wall sections, including the impact of concrete strength and flange to web ratio. The proposed equation highlighted the need for an increase in the minimum vertical reinforcement limits for non-rectangular wall sections compared to the existing minimum vertical reinforcement requirement applicable to rectangular wall sections.

Dynamic behaviors of a bubble near a rectangular wall with a bulge

In this paper, the cavitation bubble dynamics near a rectangular wall with a bulge are theoretically investigated. High-speed photography is employed to provide experimental verification of the theoretical results. Through a series of conformal transformations and the image method, the analytical description of how this complex wall configuration affects the bubble is shown to be equivalent to the superposition of eight virtual bubbles. The physical meaning of the eight virtual bubbles can be divided into four groups, corresponding to the influence of the left wall, the bottom wall, the angle formed by the two flat walls, and the bulge. The influence of the bulge on the liquid velocity distribution, as well as the intensity and direction of the Kelvin impulse exerted on the bubble, is explored for cases in which the bubble is located at symmetric and asymmetric positions. The main findings are given as follows: During the bubble collapse, a high-velocity area of the liquid exists to the side of the bubble farthest from the bulge, and three stagnation points with three low-velocity areas appear on the bulge surface. The bulge mainly influences the impulse intensity when the bubble is located near the symmetric position. The existence of the bulge causes the impulse angle to attain a minimum as the distance between the bubble and the bulge increases. For a larger bulge radius, the changes in the impulse angle become more complicated as the bubble position angle increases.

Investigation on geometric and surface finish quality of 3D concrete printed walls with hollow section

3D concrete printed walls with hollow sections are now widely adopted in 3D concrete printing applications across the construction industry. One of the significant challenges in the printing process is achieving superior surface finishes. Previous research has predominantly focused on the overall geometry of these walls, often neglecting surface finish quality at the intersections of formwork and supporting filaments. This study is dedicated to optimizing the geometric arrangement of supporting filaments and enhancing print quality at these critical intersections. Firstly, two arrangement strategies, the standard approach and the average approach, are introduced to establish high-quality geometric section configurations, with practical demonstrations on both rectangular and arc-shaped walls. Subsequently, the width of concrete filaments is considered to enhance surface finish quality at the intersections. Two print quality control methods, namely the e- Δ control rule and the r- Δ control rule, are then developed. To assess the effectiveness of these arrangement strategies and control methods, configurations of walls with specific dimensions are compared, and printing experiments are conducted. Finally, recommendations for practical application are provided, aimed at improving both the geometric and surface finish quality of 3D concrete printed walls with hollow sections.

Unsteady magneto-hydrodynamic behavior of TiO2-kerosene nanofluid flow in wavy octagonal cavity

The aim of this study is to mathematically model the behavior of magneto-hydrodynamics (MHD) in a two-dimensional unsteady flow, specifically focusing on natural convection (NC) and heat transfer (HT) within a wavy octagonal cavity. The study investigates how heat is transferred and fluid flows within this cavity under specific conditions. In particular, it examines the impact of various parameters, such as the Hartmann number (Ha), Rayleigh number (Ra), and the volume fraction of nanoparticles (ϕ) on the flow and HT patterns. This cavity includes a rectangular vertical wall (RVW) at the center of its bottom wall, filled with kerosene-TiO2 nanofluid of spherical shape. Within this setup, the RVW is maintained at a high temperature (T = Th), while the wavy wall is kept at a lower temperature (T = Tc, where Tc <Th). All other boundaries of the domain are assumed to be adiabatic. The finite element method (FEM) is employed as the solver for the relevant partial differential equations in numerical simulations. The results show excellent agreement with previously published research papers. The numerical solution transitions from an unsteady state to a steady state in approximately 0.68 dimensionless time units during the HT process. Throughout the study, various parameters are explored, including Ha, ranging from 0 to 100, Ra, ranging from 103 to 106, and ϕ, ranging from 0 to 0.05. The findings reveal distinct patterns in streamlines and isotherms. Specifically, a reduction in the rate of HT is observed as the Lorentz force increases, while the rate of HT is enhanced with increasing buoyancy force. Additionally, an expansion in ϕ led to an increase in the rate of HT. The study's findings could contribute to our understanding of fluid dynamics, heat transfer, and the behavior of nanofluids in complex geometries, potentially leading to improvements in various engineering and industrial applications.

Stochastic analysis and reliability assessment of critical RC structural components considering material properties uncertainty

The unavoidable heterogeneity in the mechanical characteristics of concrete is widely acknowledged. Although it is widely considered as either perfectly correlated or entirely independent random variables in engineering practice; however, such treatment is illogical, and the outcomes may be deceptive. In high-rise buildings comprised of multiple structural components, it is crucial to consider the material properties’ spatial variability (MPSV) to obtain a reliable structural response and avoid damage to these structures. To this end, three main components, including column, rectangular shear wall, and U-shaped shear wall, are considered herein to investigate their stochastic response. The MPSV is represented by a covariance matrix decomposition-based random field generator combined with a GF-discrepancy-based point selection strategy to generate samples efficiently. A simplified strategy is developed to represent the random field for the U-shaped wall. Moreover, the probability density evolution method combined with the extreme value event is employed to obtain the failure probability of the studied components, where failure probabilities of 18%, 23%, and 32% are recorded for the studied RC column, rectangular shear wall, and U-shaped shear wall, respectively. Furthermore, different failure modes were identified and could not be determined through the deterministic analysis, highlighting the importance of accounting for material uncertainty. The proposed framework proved that the stochastic response and non-linear behavior of the considered components could be well captured and provide full perspective about the uncertainty quantification and reliability assessment and can be further implemented to capture the stochastic response and safety assessment of high-rise buildings.

Sectional strength design of a double-skin truss-reinforced composite shear wall

The double-skin truss-reinforced composite shear wall is an innovative element which comprises two steel plates, core concrete, concrete-filled steel tubes (CFSTs), which act as boundary members, and steel truss connectors. Truss connectors decrease the out-of-plane deformation that affects the steel plates, and due to the resultant connection and constraint effects, the truss connectors enhance the bearing capacity of the wall. This paper briefly introduces the quasi-static test of five full-scale rectangular double-skin truss-reinforced composite shear wall specimens. The specimen exhibited shear compression failure with an aspect ratio of 2.0, and flexure shear failure occurred when the aspect ratio exceeded 2.0. Based on the analysis of actual stress state of the steel web and actual working performance of the infilled concrete, the shear strength and flexure strength design formulas of double-skin truss-reinforced composite shear wall were established. Comparison results with 26 specimens demonstrate that the design formulas exhibit remarkable accuracy, as most errors are within 20 % and 25 %, respectively. Which provide a preliminary sectional strength design proposal for the double-skin truss-reinforced composite shear wall.

Mechanical properties of periodic rectangular tube sandwich structure subjected to out-of-plane impact compression loading

Owing to its unique deformation form, negative Poisson’s ratio sandwich structure has attracted significantly widespread interest, especially in the impact protection field. However, inferior mechanical properties severely limit their practical applications. To enhance its mechanical properties, a new type of periodic sandwich structure of rectangular tube was designed and fabricated, and the structure presents negative Poisson’s ratio characteristic under out-of-plane impact compression load. To evaluate its mechanical properties, the deformation form and equivalent yield strength of the periodic rectangular tube sandwich structure were obtained through the split Hopkinson pressure bar (SHPB) experiment. A numerical model of the different wall thicknesses of periodic rectangular tube sandwich structure (PRTSS) was established, and the accuracy of the model was verified by comparing it with the deformation form and equivalent yield strength obtained from experimental results. The results show that with the increase of rectangular tube wall thickness in PRTSS, the equivalent yield strength increases, and the equivalent yield platform strain decreases. Moreover, through the simulation results under four different strain rates, it is obtained that the equivalent yield stress of PRTSS increases with the increase of strain rate, and the straining length of the equivalent yield platform decreases with the increase of strain rate. The effect of wall thickness and strain rate on PRTSS was analyzed, which provided certain guiding significance for the application of the structure in the field of impact protection.

Experimental study of thermal performance in a rectangular finned-tube latent heat storage device with composite polyethylene wax/expanded graphite

Phase change materials and geometric structure of latent heat storage (LHS) devices constitute crucial factors affecting the performance of phase change thermal energy storage systems. In this study, focusing on the LHS system with a heat source temperature of 150 °C, a rectangular finned-tube latent heat storage device was designed and fabricated. Polyethylene wax (PEW) with a 10% mass fraction of expanded graphite was adopted to prepare the composite phase change material. A series of experiments was conducted to evaluate the thermodynamic performance of the device with varying inlet temperatures and mass flow rates. The experimental results showed that the process of heat storage and release was predominantly governed by thermal conduction due to the high viscosity of PEW. Although the temperature variations in various directions within the LHS device remain nearly consistent, the heat transfer in the non-fin regions on the rectangular LHS device walls and corners was comparatively inferior due to the absence of natural convective heat transfer. In comparison to the mass flow rate, the inlet temperature exerts a more significant impact on accelerating the heat storage/release processes. While an increase in the mass flow rate enhanced the heat transfer capacity, its slightly accelerates the heat transfer duration. Moreover, the heat release ratio of the device exhibits an initial increase followed by a decrease with an increasing mass flow rate. In practical applications, prioritizing an increase in inlet temperature difference proves to be more effective than adjusting mass flow rate to enhance the heat storage performance.

Numerical Analysis and Experimental Investigation of High Cycle Fatigue Behavior in Additively Manufactured Ti–6Al–4V Alloy

Additive Manufacturing (AM) of the Ti–6Al–4V alloy has gained significant importance across various industries, including biomedical, aerospace, cellular, and land vehicle applications, due to its numerous benefits. The certification of performance and reliability of AM materials, particularly for critical applications, heavily relies on evaluating fatigue strength. In this study, a numerical analysis based on the finite element method is presented to predict the High Cycle Fatigue (HCF) behavior of AM Ti–6Al–4V alloy. The investigation focuses on exploring the sensitivity of material fatigue life to surface roughness and Ultimate Tensile Strength (UTS). Uniaxial tensile and High Cycle Fatigue (HCF) tests were conducted on Ti–6Al–4V alloy samples extracted from rectangular walls manufactured using the Laser Metal Deposition (LMD) process. The walls were surface machined prior to sample extraction. Porosity and surface roughness measurements were performed on the samples. Numerical simulations of the HCF tests were carried out, considering various surface roughness ranges and UTS values. The numerical results were then compared to experimental data. The findings consistently demonstrated that higher surface roughness led to a shorter fatigue life, while higher UTS values resulted in a longer fatigue life. The numerical solutions aligned with the experimental results, indicating the efficacy of the finite element method in predicting the fatigue behavior of AM Ti–6Al–4V alloy. These insights contribute to a better understanding of the relationship between surface roughness, UTS, and fatigue life of Ti–6Al–4V alloys manufactured by AM.

Melting numerical simulation of hydrated salt phase change material in thermal management of cylindrical battery cells using enthalpy-porosity model

Battery thermal management using different cooling techniques is rapidly growing. Understanding the proper cooling and melting process when phase change materials (PCM) are used is of prime importance in this area. Hence, a transient thermal-fluid and melting process of hydrated salt PCM enclosed in a battery module with six cylindrical cells is numerically investigated to understand the melting process of the PCM. Four structural models S1, S2, S3, and S4 are constructed for the present numerical simulation. The battery cell wall is kept at a constant temperature of 35℃, while the rectangular enclosure walls are assumed to be insulated. A finite volume scheme-based CFD (computational fluid dynamics) software is used to simulate the melting process of hydrated salt PCM. In order to capture the phase change phenomenon from solid to liquid, an enthalpy-porosity equation is solved. The temporal temperature distribution, liquid fraction, velocity and enthalpy are analyzed. The results obtained by the numerical computation suggest that the battery cell arrangement used in S1 and S2 model at the initial time step gives better space for temperature distribution and liquid fraction up to the time step of 420 s, while S3 and S4 model after a time interval of 420 s provide better scope for temperature distribution and complete melting of hydrated PCM.

Mechanical behaviour of reconstructed defected skull with custom PEEK implant and Titanium fixture plates under dynamic loading conditions using FEM

Skull reconstruction using cranial implants is often required for repairing skull defects caused due to trauma, diseases, or malignancy to protect intracranial structures. For relieving Intracranial Pressure (ICP) surgeons restore cranial defects either using natural bones or fabricated custom cranial implants. With the increase in Traumatic Brain Injuries (TBI) and challenges faced by TBI patients to regain normalcy, it is imperative to analyse the mechanical behaviour of skull-implant assemblies under some Head Injury Criteria (HIC). Medical grade materials including Titanium Alloys (Ti-6Al-4V) and Polyether-ether-ketone (PEEK) are used by fabricating Patient-Specific Implants (PSI) manufactured using 3D imaging, modelling and printing techniques. 3D technologies are preferred over conventional manufacturing methods, as they enable fabrication of custom shapes, sizes and properties for these PSI.For an effective attachment of PSI with a defective skull, a stable joint and plate arrangement as fixture plates is necessary at their interface. These fixtures can have variable numbers, design shapes, materials and location arrangements.This paper presents the Finite Element Method/Analysis (FEM/FEA) study of PSI attached to a defected skull for reconstruction, with linear shaped fixture configuration, when subjected to an external dynamic loading at 5 m/s, strain rate of 10s−1 to 243s−1 and ICP of 15mm Hg from three sides of the skull faces. Three different materials as Neoprene (soft), Concrete (medium rigid) and E-Glass (highly rigid) have been used, in the form of a rectangular thin cuboidal wall structure, at an angle of 45° with the skull face. Four linear shaped fixture plates which were simplest to design, were used to attach the PSI-skull assembly, to ensure that weight of the PSI-fixation assembly on the patient remains minimal, overall assembly has symmetrical fixations and efforts required by a surgeon for fitment of these plates remain minimal. Placement of these fixture plates has been optimized to encompass the complete PSI-skull interface section, due to which the stresses within all the assembly components (PSI, fixture plate and skull) reduced by nearly 2.5 times than the initial design and remained within yielding limits, thereby, averting any failure under heavy external dynamic loading.

Distortion Analysis Method for Wire Arc Additive Manufacturing Component Using Thermomechanical Computation with Enhanced Separation and Deposition Algorithm.

This research is devoted to numerical and experimental analysis on deformation of completely removed component induced by wire arc additive manufacturing (WAAM). The component has the form of a hollow and rectangular thin wall made of deposition layer of stainless steel SS316L on top of substrate plate of mild steel S235. In this research, thermomechanical finite element analysis was applied with Goldak's double ellipsoid as heat-source model and isotropic hardening rule based on von-Mises yield criterion. A specialized numerical simulation software Simufact.Welding 2021 (SW) was utilized in developing the numerical model and the simulation of process enhanced with separation and deposition algorithm to predict the component deformation after removal of substrate. On determining the best possible mesh size, a sensitivity analysis was conducted before the advanced stage of model development. An advanced material modeling, the data of which were obtained based on the chemical composition of the evolved SS316L sample, was developed using an advanced material modeling software JMATPRO. For verification purpose, a series of WAAM experiments using robotic GMAW with synergic power source were conducted followed by the removal of substrate from component using machining process. Furthermore, component distortion was measured using industrial noncontact 3D scanner with structured blue light to fully capture the upper section deformation and compared with result of numerical computation. It can be concluded that this novel distortion analysis method using thermomechanical numerical computation with evolved material property and modified algorithms for substrate removal exhibits a surface deviation in vertical direction between 0.05 and 2.16 mm with acceptable pointwise and average error percentage of up to 3%.

Transobturator Tension-Free Vaginal Flap Operation versus Synthetic Transobturator Tape for Treatment of Female Stress Urinary Incontinence: A Prospective Randomized Study

Introduction: Synthetic mid-urethral slings (MUSs) are the gold standard treatment for female stress urinary incontinence (SUI). Recently, there have been reports of serious adverse events with synthetic tapes such as urethral erosion, vaginal erosion, and mesh infection. Tension-free vaginal flap (TVF) operation has been proven to be successful as a natural alternative to synthetic slings. We propose our novel technique, the transobturator tension-free vaginal flap (TO-TVF), utilizing native vaginal tissue and being suspended via transobturator route. Methods: This prospective study was conducted on 72 female patients with SUI, presenting at Alexandria University Hospital. Patients were randomized into 2 groups, group 1: 37 patients subjected to TO-TVF and group 2: 35 patients to conventional transobturator tape (TOT). In TO-TVF, a rectangular vaginal wall flap is created. A polypropylene monofilament mesh is sutured to each edge of the vaginal flap. This is inserted like conventional outside-in TOT. Patients were subjected to PGI and UDI-6 questionnaires and urodynamic study before and 6 months postoperatively. Results: Both groups showed comparable and significant improvements in questionnaires. Mean operative time for TO-TVF and conventional TOT was 26.31 ± 5.2 min and 21.8 ± 3.1 min, respectively. Cure rate was 89% in group 1 and 91.4% in group 2, which was not statistically significant. No significant intraoperative complications were encountered. We had no cases of vaginal or urethral erosion in both groups. Conclusions: TO-TVF is a cost-effective, feasible, safe, and effective surgical alternative to synthetic MUS. Synthetic mesh tissue anchoring properties are maintained for better adjustment of tension. However, long-term follow-up on a large cohort of patients is still needed.