Infill Layer Research Articles

Experimental and numerical studies on corrugated steel retrofitted damaged reinforced concrete arches

The corrugated steel (CS) reinforcement method has been adopted for strengthening dilapidated bridges and culverts owing to its advantages of convenient construction, good corrosion resistance, and high deformability. However, the current design method for corrugated steel retrofitted damaged reinforced concrete (CSRDRC) arches is excessively conservative as it only considers the bearing capacity of the CS, neglecting the contributions of the original reinforced concrete (RC) structure and the infill layer. This paper studied the behaviour of CSRDRC arches under three-point loading experimentally and numerically. The experimental results demonstrate that the bearing capacity and initial stiffness of the arches are significantly enhanced after CS reinforcement. The increase in damage degree of the original structure has a slight effect on the bearing capacity and initial stiffness, but an obvious adverse effect on the ductility of the CSRDRC arches. A finite element model (FEM) was developed and verified against test results and then utilized to conduct parametric analysis. Finally, a simplified formula was proposed for predicting the axial compressive bearing capacity of CSRDRC arches.

Optimization of Topology and Mechanical Properties of 3D Printed Hollow and Thin-Walled Structures via Integration of Taguchi Method and Grey Relational Analysis

Fused deposition modelling (FDM) as one of 3D printing technique allow for the layer-by-layer construction of objects from a CAD file using a variety of different materials. The process has become quicker and more versatile as a result of technological innovation. In this study, the Taguchi method and Grey Relational Analysis (GRA) were integrated to examine the mechanical performance and topology optimisation of polylactic acid (PLA) 3D printed hollow and thin-walled structures by FDM. The results showed that the optimized factors for the 3D printed part were identified as topology design (hexagonal), wall thickness (2 mm), layer height (0.2 mm), infill density (20%), infill layer thickness (0.6 mm), infill flow (80%), infill pattern (Triangle), print speed (100 mm/s), printing temperature (210°C), bed temperature (65°C), and orientation direction (flat along the Y-axis). The compression properties of the 3D printed part particularly for maximum force, maximum stress and compression modulus were improved by 15.42%, 66.62% and 68.61% respectively after the optimization.

Investigation of Polylactic Acid 3D Printed Hollow and Thin-Walled Structures through Topology and Mechanical Properties Optimization Using Integration of Taguchi Method and Principal Component Analysis

Fused deposition modelling (FDM) is a spectrum of techniques that enables the fabrication of objects from diverse materials, layer-by-layer, and directly from a CAD file. With the advancement of technology, the procedure has grown more adaptable and swifter. In this study, the mechanical performance and topology optimization of the polylactic acid (PLA) 3D printed hollow and thin-walled structures produced by FDM was investigated via integration of Taguchi method and Principal Component Analysis (PCA). Eleven factors namely topology design (square), wall thickness (1 mm), layer height (0.3 mm), infill density (20%), infill layer thickness (0.6 mm), infill flow (80%), infill pattern (Octet), print speed (80 mm/s), printing temperature (210°C), bed temperature (65°C), and orientation direction (flat along the y-axis) were identified as the optimal factors for the 3D printed part. The integration approach concurrently solves the problem in particular for numerous quality criteria, especially in 3D printing. Integrating the Taguchi method with PCA can help to improve the quality of the final product or process, and enhance the understanding of the underlying relationships between variables.

Pengaruh Parameter Proses 3D Printing Terhadap Kuat Bentur Menggunakan Fiamen Polycarbonate

The existence of this 3D printing technology in manufacturing has brought big companies to the world of industry. One of the rapid prototyping technologies that are often found in the market today is the FDM type of technology. Fused Deposition Modeling (FDM) technology is a printing technique used to print products using fibrous materials, printed products have ideal geometric characteristics. Impact test is a method used to determine the strength, hardness and ductility of a material. In this impact test, rapid loading is used. The method used is Taguchi and this study aims to obtain optimal process parameters in the impact test. Printing was carried out with a 3D printing machine Creality Ender 3 which printed 81 specimens. Then the impact test was carried out so that the highest average value of the impact test results was in experiment number 27 with a value of 0.00392 joules and for the lowest impact test value was in experiment number 1 with a value of 0.00291 Joules. The method used in this process parameter optimization research is the Taguchi L9 OA method. for the factors used, namely printing speed, infill layer thickness, wall thickness, print temperature. . the results of the research that has been carried out show the optimum parameter values ​​and parameters that influence the impact test successively, namely printing speed (40mm/s), infill layer thickness (0.2mm), wall thickness (2.0mm), print temperature (250 ℃), bed temperature(250℃), infill overlap(30mm), raft extra margin(7.5mm), wall printing speed(22.5mm/s). It was found that the highest average value of the impact test results was in experiment number 2 with a value of 0.031 joules and the lowest impact test value was in experiment number 7 with a value of 0.026 Joules.

Assessment of Number of Layers on Tensile and Bend Strength of HB 500 and ST 42 Dissimilar Weldments

The joining of several materials with different characteristics has been widely carriedout for industrial progress, especially to obtain material characteristics that are superior to theprevious one. One of the most common joining techniques is welding. This research wasconducted to determine the weldability of different steels with the number of layers varyingbetween 3 and 4 layers. The object of this research is the welded connection of HB 500 wear-resistant steel plate with ST 42 construction steel plate where the thickness of each material is 10mm. Welding with the Gas Metal Arc Welding (GMAW) method employes ER 70 S filler metal ineach layer and currents from 90 A to 180 A at each connection. Tensile and bending tests werecarried out as a characterization of the weld area to determine its mechanical properties. Theresults show a significant effect of the number of layers on the quality of the connection. Theoptimum value is formed in the number of infill layers as much as 4 layers with tensile strengthof 448.37 - 473.292 MPa, yield stress of 305.767 - 317.493 MPa, elongation of 33.8 - 34.56%, andable to bend under load 874,498 - 919,544 MPa with angle formed are 85.414° on the root and86.14° on the face.

Influence of Thermal Processing for 3D Printed Components

In the medical field the additive manufacturing process by fused deposition modeling has gained a great importance given the ability to create complex, organic geometries, in a short time period and the possibility of high customization. By fused deposition process the part is created layer by layer and the resulting part is characterized by high anisotropy, dictated mostly by printing parameters. To alleviate the anisotropy and to study the mechanical behavior of the 3D printed parts thermal processing is used. The materials used as filament is a poly (lactic acid) with copper particles embedded for antibacterial purposes. Samples were 3D printed using a commercial printer, thermally processed and tested in compression. On the failed specimens fracture investigations were performed to understand mechanical behavior during compression. The mechanical characteristics showed improvement and the anisotropy decreased as the processing temperature increased, but the samples became brittle. The mechanical behavior changed drastically on the thermally processed samples because of structural changes: a discontinuity between exterior layers and infill layers was created post layer fusion, the first region being the one stressed and failed first during tests.

Assessment of hygrothermal performance of hemp concrete compared to conventional building materials at overall building scale

The aim of this paper is to analyse the impact of hemp concrete on the overall hygrothermal behaviour of the building when it used as an infill layer in the envelope of wood-frame structures. Three wall configurations were considered in different climates. Then, a hygrothermal co-simulation approach was used to integrate the model of coupled heat and moisture transfer through multilayered walls in a dynamic thermal simulation tool for the building. The material properties which constitute the input parameters for the model were determined experimentally, according to the hygrothermal state of the material. The results showed that hemp concrete significantly reduces the energy consumption of the building and has better insulation properties than the two conventional building materials: brick and aerated concrete. This is justified by the good hygrothermal properties of this bio-based material, especially its high thermal resistance of 3.08 K.m2/W compared to 0.88 K.m2/W of brick and 2.28 K.m2/W of aerated concrete. In addition, for the three climates considered, the thermal comfort of the hemp concrete envelope is significantly improved. This material also allows stabilisation of relative humidity levels in the ambient air by naturally regulating the hygrometry, to ensure better ambience. The study shows that hemp concrete has interesting hygrothermal properties. Thus, this material can be used massively in the construction field in order to meet the requirements of the current standards which aim to reduce the energy and environmental impacts of dwelling and office building.

Multi-Leaf Stone Masonry Walls in Egypt: A Legend

Multi-leaf stone masonry walls are a typical construction technique in architectural heritage in Egypt. The assessment, modeling, and strengthening of historic masonry walls of multi-leaf systems essentially require suitable knowledge of their construction technology, typology, geometrical characteristics, and the properties of their components. Within the current research project, a comprehensive structural survey of multiple-leaf walls of medieval historic buildings in Cairo was performed. The observation and statistical analyses allowed characterization of the transversal section of the surveyed walls, as well as examination and identification of the construction materials and techniques. The slenderness ratios of this type of wall, its blocks’ dimensions, the utilized connectivity between the inner and outer leaves, and leaves ratio were also investigated. Three construction hypotheses of multiple-leaf stone masonry walls are presented considering weak, thick, and monolithic core infill layers. The study’s objectives were to enlarge the knowledge of typology, morphology, and construction materials used in three-leaf masonry walls and provide a proper characterization as a prerequisite for determining the most suitable materials and techniques for further strengthening interventions.

Rock magnetic study of grave infill as a key to understanding magnetic anomalies on burial ground

AbstractMagnetic prospecting of burial grounds is still a great challenge in the field of archaeological geophysics. Some graves appear as positive anomalies, whereas others do not generate any traces or even show up by negative anomalies. This study involves ground magnetic survey, rock magnetic and magnetic mineralogy examinations of soils to determine factors responsible for the formation of magnetic anomalies on Late Roman time burial grounds of Chernyakhiv–Sântana de Mureş archaeological culture located in the forest‐steppe of Ukraine. We surveyed these sites by a total magnetic field caesium magnetometer in order to target the archaeological excavations. We sampled infill from graves excavated under positive anomalies and profiles of background soils to analyse the enhancement of induced and remanent magnetization. In the laboratory, we examined magnetic mineralogy and measured various magnetic parameters and ratios characterizing concentration and granulometry of ferrimagnetic phase of soils. For further explanations of the magnetic anomalies, we created 3D synthetic magnetic models of the studied objects and compared the calculated total field anomalies with field measurements by their intensity and size. Here, we show how positive magnetic anomalies of destroyed burials are generated when a destruction pit remains open and later topsoil material gradually refilled it with aid of precipitation water. In this case, the infill layers acquire detrital remanence of the same intensity as the topsoil. Such burials are the best targets for magnetic survey. However, archaeological excavations revealed both intact and destroyed inhumations that caused no magnetic disturbance. Obviously, they were refilled immediately after digging/destruction, so that natural remanence of the infill remains mechanically destroyed. The study of this specific category of archaeological monuments brought us closer in the understanding the formation of magnetic anomalies in soil‐filled features and showed the potential and limitations of magnetic prospection.

The Influence Of Process Parameters On The Surface Roughness Of The 3d Printed Part In FDM Process

3D printing is a promising digital manufacturing technique that produces parts with layer by layer. The influence of process parameters is investigated for ABS material in fused deposition modelling (FDM). This work aimed to determine the surface roughness of 3d printed parts of the ABS material with varied parameters of infill height and infill density. The results of the test show that the, surface roughness is higher (11.6mm) at 20% infill density with 0.26mm infill layer height. Also, ABS material surface shows good finish (lower surface roughness) at 100% infill density with 0.06mm infill layer height. The infill layer height clearly visible under microscope at higher infill layer height with all the infill densities.

Traction forces generated during studded boot‐surface interactions on third‐generation artificial turf: A novel mechanistic perspective

The traction forces generated during studded boot‐surface interactions affect player performance and injury risk. Over 20 years of empirical research into traction on third‐generation (3G) artificial turf has met with only limited success in supporting the development of safer surfaces and boots. Thus, the purpose of this perspective article is to present a conceptual framework for generating scientific understanding on 3G turf traction through a novel mechanistic approach. A three‐stage framework is proposed. Firstly, the hypothesized traction mechanisms and related analytical equations are identified, namely, friction between the boot outsole and surface; shear resistance of the performance infill layer to the outsole; and compressive resistance of the performance infill layer to horizontal stud displacement. Secondly, a Concept Map is generated to visually represent the contribution of the 39 variables identified as directly affecting the traction response. Finally, a Research Roadmap is constructed to guide the direction of future traction studies toward the development of safer surfaces and boots as well as improved mechanical tests to assess surface safety. The proposed framework represents the first attempt to deconstruct boot‐surface interactions and hypothesize the science behind the mobilization of traction forces.

Hydrogeochemical Evolution and Heavy Metal Contamination in Groundwater of a Reclaimed Land on Zhoushan Island

The need for valuable land has encouraged reclamation in coastal areas worldwide in the past decades. Land reclamation can alter the groundwater quality in coastal aquifers. The purpose of this study is to identify the effect of land reclamation on groundwater chemistry, especially the major ions, and heavy metals on Zhoushan Island, China. The subsurface media on the island is composed of two layers, i.e., an upper infill layer and an underlain clay layer. The upper layer is previously ocean and filled with various materials. The clay layer is the original marine sediment. The dominated Na and Cl ions in groundwater illustrate high salinity sources of groundwater in the subsurface of the reclaimed land. A mixing trend between seawater and river water of the groundwater in infill layer is also detected based on the ratios of Cl and Br. Though the heavy metal concentrations (Cd, Cr, Zn and Hg) are high in marine sediments, no significant releasing trends in the groundwater are detected in a short-term after reclamation (based on standard GB18668). Meanwhile, Fe-III concentrations in the aquifer have a strong correlation with precipitation events. Column desorption experiments and simulations indicate the Cd and Cr release from the sediment would pose a health risk when the groundwater in the infill layer being gradually flushed by fresh water. These results provide a foundation for the prediction of groundwater quality and are helpful for the future water management in a newly reclaimed land.

Morphological Expressions of Crater Infill Collapse: Model Simulations of Chaotic Terrains on Mars

AbstractMartian chaotic terrains are characterized by deeply depressed intensively fractured areas that contain a large number of low‐strain tilted blocks. Stronger deformation (e.g., higher number of fractures) is generally observed in the rims when compared to the middle regions of the terrains. The distribution and number of fractures and tilted blocks are correlated with the size of the chaotic terrains. Smaller chaotic terrains are characterized by few fractures between undeformed blocks. Larger terrains show an elevated number of fractures uniformly distributed with single blocks. We investigate whether this surface morphology may be a consequence of the collapse of the infill of a crater. We perform numerical simulations with the Discrete Element Method and we evaluate the distribution of fractures within the crater and the influence of the crater size, infill thickness, and collapsing depth on the final morphology. The comparison between model predictions and the morphology of the Martian chaotic terrains shows strong statistical similarities in terms of both number of fractures and correlation between fractures and crater diameters. No or very weak correlation is observed between fractures and the infill thickness or collapsing depth. The strong correspondence between model results and observations suggests that the collapse of an infill layer within a crater is a viable mechanism for the peculiar morphology of the Martian chaotic terrains.

A multi-layer parallel crack extension model for deformational response of post-installed anchor

A simultaneous crack extension pull-out model for post-installed anchor bar is presented. The anchor bar is such that used in various strengthening techniques to strengthen reinforced concrete structures. The properties of the infill material used for post-installed anchor bar are characterized by a nonlinear interface between the surrounding concrete and the anchor bar. This is a new type of anchor-infill assembly in which the infill material is divided into two layers for the purpose of providing a larger failure path length resulting in increase of the energy absorption and pull-out load capacity. The mechanical properties of the infill layer are different from the surrounding concrete. Therefore the existing pull-out model of deformed bars cannot be applied directly in this case. The interfacial de-bonding is examined by the strength criterion expressed in terms of interfacial shear stress. Pre-existing cracks representing artificial notches are assumed at the top of infill layers for identifying crack location and stabilizing its propagation direction. All the possibilities associated with two-cracks in the close vicinity have been investigated in detail. The objective of the analysis is to predict a set of material properties which result in simultaneous crack extension at the two interfaces and also to identify a simultaneous crack extension length which results in increasing the pull-out load capacity, increase in energy absorption and increased failure path length but achieved at lowest increase in pull-out deformation thereby proving the effectiveness of two-layer model. Limiting the pull-out deformation is desirable from the point of view of limiting damage.

TWO-LAYER SIMULTANEOUS CRACK EXTENSION MODEL FOR PULL-OUT BEHAVIOR OF POST-INSTALLED ANCHOR

A simultaneous crack extension pull-out model for post-installed anchor is presented. The anchor is such that used in various strengthening techniques for reinforced concrete structures. The properties of the infill material used for post-installed anchor are characterized by a nonlinear interface between the surrounding concrete and the anchor. This is a new type of anchor-infill assembly in which the infill material is divided into two layers for the purpose of providing a larger failure path length resulting in increase of energy absorption and pull-out load capacity. The mechanical properties of the infill layer are different from the surrounding concrete. Therefore, the existing pull-out model of deformed bars cannot be applied directly in this case. The interfacial de-bonding is examined by the strength criterion expressed in terms of interfacial shear stress. Pre-existing cracks representing artificial notches are assumed at the top of infill layers for identifying crack location and stabilizing its propagation direction. All the possibilities associated with two-cracks in the close vicinity have been investigated in detail. The objective of the analysis is to predict a set of material properties which result in simultaneous crack extension at the two interfaces and also to identify a simultaneous crack extension length which results in increasing the pull-out load capacity, energy absorption and failure path length, achieved at lowest increase in pull-out deformation. Limiting the pull-out deformation is desirable from the point of view of limiting damage. From the analysis, using proposed material properties and dimension parameters, simultaneous crack extension length, Ld equal to 0.3 is identified as the ideal length which results in increasing the pull-out load capacity by 31%, increasing the failure path length by 30% and increase the energy absorption capacity by 47% achieved at an limited increase in pull-out displacements of 20%.

TWO-LAYER MODEL FOR PULL-OUT BEHAVIOR OF POST-INSTALLED ANCHOR

A new two-layer anchor-infill assembly structure for the post-installed anchor is introduced with the analytical model to simulate its pull-out deformational response. The post-installed anchor is such that used in strengthening techniques for reinforced concrete structures. The properties of the infill material used for post-installed anchor are characterized by nonlinear interfaces. Because of the mechanical properties of the infill layer the existing pull-out model of deformed bars is not applicable in this case. Interfacial de-bonding is examined using energy criterion and strength criterion. The effect of the interface properties such as stiffness and strength on the pull-out behavior of a post-installed anchor is investigated. Using sensitivity analysis, the effect of these parameters on load-displacement curve, shear stress distribution, de-bonded length and damage to the surrounding concrete is clarified. Then, the optimum combination of these parameters is presented. It is confirmed that the elastic modulus of infill should be large to reduce the pull-out displacement and the increase of the shear strength of infill makes the pull-out load larger.

The effects of various infills, fibre structures, and shoe designs on generating rotational traction on an artificial surface

The purpose of this study was to investigate the role of infill material and fibre structure on the rotational traction associated with American football shoes on infill-based artificial surfaces. A mobile testing apparatus with a compliant ankle was used to apply rotations and measure the torque produced at the football shoe—surface interface. The mechanical surrogate was used to compare three infill materials in combination with three fibre structures, creating a total of nine unique surfaces. Infill material, fibre structure, and shoe design were all found to significantly affect rotational traction. The cryogenically processed styrene—butadiene rubber (SBR) infill yielded significantly higher peak torques than the ambient ground SBR and extruded thermoplastic elastomer (TPE) infills. An artificial surface with a nylon root zone yielded significantly lower peak torques than similar fibre surfaces without a nylon root zone. The size of infill particles and the presence of a nylon root zone may influence the compactness of the infill layer. These features may act to alter the amount of cleat contact with the infill, thereby influencing rotational traction. The amount of cleat contact with the surface may also be determined by the shoe design.