scholarly journals Dynamic Properties and Fractal Characteristics of 3D Printed Cement Mortar in SHPB Test

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5554
Author(s):  
Yixin Mo ◽  
Songlin Yue ◽  
Qizhen Zhou ◽  
Bowei Feng ◽  
Xiao Liu
Keyword(s):  
Compressive Strength ◽  
Fractal Dimension ◽  
Energy Dissipation ◽  
3D Printing ◽  
Cement Mortar ◽  
Dynamic Properties ◽  
3D Printed ◽  
Fractal Characteristics ◽  
Dynamic Compressive Strength ◽  
Printing Direction

Comparing with the traditional construction process, 3D printing technology used in construction offers many advantages due to the elimination of formwork. Currently, 3D printing technology used in the construction field is widely studied, however, limited studies are available on the dynamic properties of 3D printed materials. In this study, the effects of sand to binder ratios and printing directions on the fractal characteristics, dynamic compressive strength, and energy dissipation density of 3D printed cement mortar (3DPCM) are explored. The experiment results indicate that the printing direction has a more significant influence on the fractal dimension compared with the sand to binder ratio (S/B). The increasing S/B first causes an increase and then results in a decline in the dynamic compressive strength and energy dissipation of different printing directions. The anisotropic coefficient of 3DPCM first is decreased by 20.67%, then is increased by 10.56% as the S/B increases from 0.8 to 1.4, showing that the anisotropy is first mitigated, then increased. For the same case of S/B, the dynamic compressive strength and energy dissipation are strongly dependent on the printing direction, which are the largest printing in the Y-direction and the smallest printing in the X-direction. Moreover, the fractal dimension has certain relationships with the dynamic compressive strength and energy dissipation density. When the fractal dimension changes from 2.0 to 2.4, it shows a quadratic relationship with the dynamic compressive strength and a logarithmic relationship with the energy dissipation density in different printing directions. Finally, the printing mortar with an S/B = 1.1 is proved to have the best dynamic properties, and is selected for the 3D printing of the designed field barrack model.

scholarly journals Study on the Fractal Characteristics of the Pomegranate Biotite Schist under Impact Loading

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Jianguo Wang ◽  
Ting Zuo ◽  
Xianglong Li ◽  
Zihao Tao ◽  
Jun Ma
Keyword(s):  
Compressive Strength ◽  
Fractal Dimension ◽  
Energy Consumption ◽  
Energy Dissipation ◽  
Strain Rate ◽  
Power Relationship ◽  
Strain Rates ◽  
Biotite Schist ◽  
Fractal Characteristics ◽  
Dynamic Compressive Strength

In order to study the fractal characteristics of the pomegranate biotite schist under the effect of blasting loads, a one-dimensional SHPB impact test was carried out to test the dynamic compressive strength, damage morphology, fracture energy dissipation density, and other parameters of the rocks under different strain rates; besides, sieve tests were conducted to count the mass fractal characteristics of the crushed masses under different strain rates to calculate the fractal dimension of the crushed rock D . Finally, the relationships between fractal dimension and dynamic compressive strength, crushing characteristics, and energy dissipation characteristics were analysed. The results show that under different impact loads, the strain rate effect of the rock is significant and the dynamic compressive strength increases with the increasing strain rate, and they show a multiplicative power relationship. The higher the strain rate of the rock, the deeper the fragmentation and the higher the fractal dimension, and the fractal dimension and rock crushing energy density are multiplied by a power relationship. By performing the comparative analysis of the pomegranate biotite schist, a reasonable strain rate range of 78.75 s-1~82.51 s-1 and a reasonable crushing energy consumption density range of 0.78 J·cm-3~0.92 J·cm-3 were determined. This research provides a great reference for the analysis of dynamic crushing mechanism, crushing block size distribution, and crushing energy consumption of the roadway surrounding rock.

Enhancement of the Compressive Strength of 3D-Printed Polylactic Acid(PLA) by Controlling Internal Pattern

2021 ◽  
Vol 1023 ◽  
pp. 75-81
Author(s):  
Aappo Mustakangas ◽  
Atef Hamada ◽  
Antti Järvenpää
Keyword(s):  
Compressive Strength ◽  
3D Printing ◽  
Polylactic Acid ◽  
Optical Microscope ◽  
Fused Filament Fabrication ◽  
Loading Direction ◽  
Compressive Flow ◽  
3D Printed ◽  
Cost Efficient ◽  
Loading Axis

Cost-efficient 3D-printing can create a lot of new opportunities in engineering as it enables rapid prototyping of models and functional parts. In the present study, Polylactic acid (PLA) cubic specimens with different types of infill patterns (IPs), rectilinear, grid and cuboid, were additively manufactured by Fused Filament Fabrication 3D-printing. The PLA cubes are fabricated with one perimeter and different IPs density (10, 20, and 30%). Subsequently, the compressive strengths of the PLA materials were measured in two loading directions, i.e., the layers building direction is parallel (PD) to the loading axis and perpendicular (ND) to the loading direction. An optical microscope was used to examine the deformed IPs in both loading directions. The compressive flow stress curves of the PLA cubes infilled with rectilinear and grid patterns exhibited strong fluctuations with lower compressive strengths in the loading direction along ND. The PLA with 30% grid IP revealed a superior strength of ~12 kN in the loading direction along PD. On the contrary, the same material exhibited a worst compressive strength 3 kN along ND.

scholarly journals Predicting Compressive Strength of 3D Printed Mortar in Structural Members Using Machine Learning

2021 ◽  
Vol 11 (22) ◽  
pp. 10826
Author(s):  
Hamed Izadgoshasb ◽  
Amirreza Kandiri ◽  
Pshtiwan Shakor ◽  
Vittoria Laghi ◽  
Giada Gasparini
Keyword(s):  
Machine Learning ◽  
Compressive Strength ◽  
Cement Mortar ◽  
Iteration Process ◽  
Machine Learning Method ◽  
Structural Members ◽  
Grasshopper Optimization Algorithm ◽  
3D Printed ◽  
Grasshopper Optimization ◽  
Artificial Neural Network Ann

Machine learning is the discipline of learning commands in the computer machine to predict and expect the results of real application and is currently the most promising simulation in artificial intelligence. This paper aims at using different algorithms to calculate and predict the compressive strength of extrusion 3DP concrete (cement mortar). The investigation is carried out using multi-objective grasshopper optimization algorithm (MOGOA) and artificial neural network (ANN). Given that the accuracy of a machine learning method depends on the number of data records, and for concrete 3D printing, this number is limited to few years of study, this work develops a new method by combining both methodologies into an ANNMOGOA approach to predict the compressive strength of 3D-printed concrete. Some promising results in the iteration process are achieved.

Generation and Investigation of Embedded Micro-Channels Network Using Three Dimensional Printing Technology

2017 ◽  
Author(s):  
Austin Smith ◽  
Hamzeh Bardaweel
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Hydrodynamic Characteristics ◽  
Shear Stresses ◽  
Printing Technology ◽  
Micro Channels ◽  
3D Printed ◽  
Printing Direction

The work presented here is motivated by the recent growing interest in using additive manufacturing to fabricate micro-channels networks. Distorted shapes and rough geometries influence hydrodynamic characteristics of micro-channels by increasing their flow resistance and pressure drop or altering wall shear stresses inside them. Since geometric conformity and shape fidelity of micro-channels networks are greatly influenced by manufacturing process, this work is focused on dimensional characterization of micro-channels fabricated using additive manufacturing. In this work, circular and rectangular cross-section micro-channels are 3D printed. Shapes and dimensions of 3D printed micro-channels are examined using Scanning Electron Microscope (SEM) imaging. In this work, 500 μm diameter and 200 μm square transparent PolyLactic Acid (PLA) micro-channels are 3D printed with average errors 0.25% and 1.65%, respectively. SEM images confirmed geometric conformity and shape fidelity of the 3D printed circular and rectangular cross-section micro-channels. Statistical analysis is performed on multiple prints to verify reproducibility and shape conformity. Results show that factors such as printing direction play essential role in the shape conformity and geometric fidelity of the micro-channels. Although 3D printing is a promising route for attaining micro-channels there are still significant improvements that can be made to the precision of the printer in the XY plane for printing small geometric figures. This improvement will likely come as the printing technology and software both improve to allow the operator more control over the outcome of the print. Additionally, new 3D printing materials may open the gate for new applications in different fields such as thermal management and microfluidics.

scholarly journals Research on the Impact Loading and Energy Dissipation of Concrete after Elevated Temperature under Different Heating Gradients and Cooling Methods

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1651 ◽  
Author(s):  
Yue Zhai ◽  
Yubai Li ◽  
Yan Li ◽  
Wenqi Jiang ◽  
Xuyang Liu
Keyword(s):  
Fractal Dimension ◽  
Energy Dissipation ◽  
Loading Rate ◽  
Heating Temperature ◽  
Fragment Size ◽  
Fragment Size Distribution ◽  
Loading Rates ◽  
Heating Treatment ◽  
Fractal Characteristics ◽  
Cooling Methods

To provide theoretical basis for fire rescue, post-disaster safety evaluation, and reinforcement of concrete structures, C35 concrete materials are treated with high-temperature heating (200 °C, 400 °C, 600 °C, 800 °C) under two different heating gradients. After natural cooling and water cooling to normal temperature, an impact compression test was carried out at different loading rates using a Split Hopkinson Pressure Bar (SHPB) system with a diameter of 100 mm, and finally the crushed specimens were subjected to a sieving test. The effects of elevated temperatures, cooling methods, heating gradients, and loading rates on the fragment size distribution, fractal characteristics, and energy dissipation of impact-compressed concrete specimens were studied. The results show that with the increase of the loading rate and the rise of the heating temperature, the crushing degree of concrete specimens gradually increases, the average fragment size decreases, and the mass distribution of the fragments move from the coarse end to the fine end. The fragment size distribution of the specimen has obvious fractal characteristics. In addition, its fractal dimension increases with the increase of loading rate and heating temperature, the average size of the specimen fragments decreases correspondingly, and the fracture of the specimen becomes more serious. When the different heating gradients were compared, it was found that the fractal dimension of the specimens subjected to rapid heating treatment was larger than that of the slow heating treatment specimens, and the crushing degree of the specimens with different cooling methods was discrete. By analyzing the energy dissipation of the specimen under different conditions, it is shown that both the fractal dimension and the peak stress increase with the increase of the fragmentation energy dissipation density. It shows that there is a close correlation between the change of fractal dimension and its macroscopic dynamic mechanical properties.

scholarly journals The Effect of Heat Treatment on Dynamic Properties of an Additively Manufactured Ti-6Al-4V Alloy

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 111
Author(s):  
Shuangyin Zhang ◽  
Yunfei Wang ◽  
Tao Suo ◽  
Jin Yao ◽  
Xin Lin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Internal Stress ◽  
Dynamic Properties ◽  
Microstructural Analysis ◽  
Rate Sensitivity ◽  
Heat Treated ◽  
Before And After ◽  
Dynamic Compressive Strength ◽  
Size And Morphology

Heat treatment processing is commonly applied for additively manufactured metal materials, since the as-fabricated material frequently exhibits high internal stress and self-cracking. In this work, a heat treatment route was applied to an additively manufactured Ti-6Al-4V alloy, and its effect on the dynamic compressive behavior was investigated. The experimental results showed that the heat treatment process not only increased the dynamic compressive strength of the material, but also induced a change of the dynamic compressive strength from isotropic to anisotropic. In addition, the strain rate sensitivity of the material was reduced by heat treatment, even though both the as-deposited and heat-treated samples demonstrated positive sensitivity to the loading rate. Microstructural analysis suggested that the grain size and morphology were the same before and after heat treatment, while the internal stress increased due to heat treatment.

scholarly journals Influences of Curing Period and Sulfate Concentration on the Dynamic Properties and Energy Absorption Characteristics of Cement Soil

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1291
Author(s):  
Jing-Shuang Zhang ◽  
Xiang-Gang Xia ◽  
Bin Ren
Keyword(s):  
Compressive Strength ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Properties ◽  
Solution Concentration ◽  
Sulfate Concentration ◽  
Hopkinson Pressure Bar ◽  
Absorption Energy ◽  
Curing Period ◽  
Dynamic Compressive Strength ◽  
Cement Soil

To study the influences of curing period and sulfate concentration on the dynamic mechanical properties of cement soil, this study used a split Hopkinson pressure bar device. Impact tests were conducted on cement soil specimens with different curing periods and different sulfate concentrations. The relationships between the dynamic stress–strain, dynamic compressive strength, and absorption energy of these cement soil specimens were analyzed. The test results show that with continuous loading, cement soil specimens mainly experience an elastic stage, plastic stage, and failure stage; with increasing curing period and sulfate concentration, the dynamic compressive strength and absorption energy of cement soil specimens follow a trend of first increasing and then decreasing. The dynamic compressive strength and absorption energy of cement soil specimens reached maximum values at a curing period of 14 d and a Na2SO4 solution concentration of 9.0 g/L. Increasing the dynamic compressive strength and absorption energy can effectively improve the ability of cement soil specimens to resist damage. This paper provides a practical reference for the application of cement soil in dynamic environments.

scholarly journals The Impact of Defects on Tensile Strength and Modulus of 3D Printed Parts Manufactured by Fused deposition Modeling

2021 ◽  
Author(s):  
Mobina Movahedi
Keyword(s):  
Tensile Strength ◽  
3D Printing ◽  
Fused Deposition Modeling ◽  
Research Work ◽  
Layer By Layer ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
3D Printed ◽  
The Impact ◽  
Printing Direction

Additive manufacturing (AM), 3D printing, is defined as a process of depositing materials layer by layer to create three-dimensional printed models, as opposed to subtractive manufacturing methodologies. It has the potential of revolutionizing field of manufacturing, which allows us to create more complex geometries with lower cost and faster speed in comparison to injection molding, compression forming, and forging. Therefore, 3D printing can shorten the design manufacturing cycle, reduce the production cost, and increase the competitiveness. Due to the improvements of processes and advancements of modeling and design, Fused Deposition Modeling (FDM) technologies, a common 3D printing technique, have been involved in wide various applications in the past three decades and numerous studies have been gathered. This research work studies directional properties of FDM 3D printed thermoplastic parts per ASTM D638. Tensile strength and modulus of the coupons along and perpendicular to the printing direction are evaluated. It is observed that FDM 3D printing introduces anisotropic behavior to the manufactured part, e.g. tensile strength of 57.7 and 30.8 MPa for loading along and perpendicular to the printing direction, respectively. FDM 3D printers are not ideal and introduce defects into the manufactured parts, e.g. in the form of missing material, gap. This study investigates the impact of gaps on tensile strength and modulus of 3D printed parts. A maximum reduction of 20% in strength is found for a gap (missing bead) along the loading direction.

scholarly journals The Impact of Defects on Tensile Strength and Modulus of 3D Printed Parts Manufactured by Fused deposition Modeling

2021 ◽  
Author(s):  
Mobina Movahedi
Keyword(s):  
Tensile Strength ◽  
3D Printing ◽  
Fused Deposition Modeling ◽  
Research Work ◽  
Layer By Layer ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
3D Printed ◽  
The Impact ◽  
Printing Direction

Additive manufacturing (AM), 3D printing, is defined as a process of depositing materials layer by layer to create three-dimensional printed models, as opposed to subtractive manufacturing methodologies. It has the potential of revolutionizing field of manufacturing, which allows us to create more complex geometries with lower cost and faster speed in comparison to injection molding, compression forming, and forging. Therefore, 3D printing can shorten the design manufacturing cycle, reduce the production cost, and increase the competitiveness. Due to the improvements of processes and advancements of modeling and design, Fused Deposition Modeling (FDM) technologies, a common 3D printing technique, have been involved in wide various applications in the past three decades and numerous studies have been gathered. This research work studies directional properties of FDM 3D printed thermoplastic parts per ASTM D638. Tensile strength and modulus of the coupons along and perpendicular to the printing direction are evaluated. It is observed that FDM 3D printing introduces anisotropic behavior to the manufactured part, e.g. tensile strength of 57.7 and 30.8 MPa for loading along and perpendicular to the printing direction, respectively. FDM 3D printers are not ideal and introduce defects into the manufactured parts, e.g. in the form of missing material, gap. This study investigates the impact of gaps on tensile strength and modulus of 3D printed parts. A maximum reduction of 20% in strength is found for a gap (missing bead) along the loading direction.

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