Bending characteristics of all-composite hexagon honeycomb sandwich beams: experimental tests and a three-dimensional failure mechanism map

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

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Investigation of Pressure Oscillation and Cavitation Characteristics for Submerged Self-Resonating Waterjet

Applied Sciences ◽

10.3390/app11156972 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6972

Author(s):

Lihua Cui ◽

Fei Ma ◽

Tengfei Cai

Keyword(s):

Sudden Change ◽

Three Dimensional ◽

Pressure Oscillation ◽

Experimental Tests ◽

Low Pressure ◽

The Self ◽

Two Phase ◽

Cavitation Phenomenon ◽

Pressure Zone ◽

Unsteady Characteristics

The cavitation phenomenon of the self-resonating waterjet for the modulation of erosion characteristics is investigated in this paper. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the unsteady characteristics of the self-resonating jet. The numerical model employs the mixture two-phase model, coupling the realizable turbulence model and Schnerr–Sauer cavitation model. Collected data from experimental tests were used to validate the model. Results of numerical simulations and experimental data frequency bands obtained by the Fast Fourier transform (FFT) method were in very good agreement. For better understanding the physical phenomena, the velocity, the pressure distributions, and the cavitation characteristics were investigated. The obtained results show that the sudden change of the flow velocity at the outlet of the nozzle leads to the forms of the low-pressure zone. When the pressure at the low-pressure zone is lower than the vapor pressure, the cavitation occurs. The flow field structure of the waterjet can be directly perceived through simulation, which can provide theoretical support for realizing the modulation of the erosion characteristics, optimizing nozzle structure.

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Numerical and experimental investigation for enhancing the energy absorption capacity of the novel three-dimensional printed sandwich structures

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420721997490 ◽

2021 ◽

pp. 146442072199749

Author(s):

H Geramizadeh ◽

S Dariushi ◽

S Jedari Salami

Keyword(s):

Energy Absorption ◽

Sandwich Structures ◽

Three Dimensional ◽

Absorption Capacity ◽

The Novel ◽

Energy Absorption Capacity ◽

Fused Deposition ◽

Honeycomb Sandwich ◽

Out Of Plane ◽

Vertical Walls

The current study focuses on designing the optimal three-dimensional printed sandwich structures. The main goal is to improve the energy absorption capacity of the out-of-plane honeycomb sandwich beam. The novel Beta VI and Alpha VI were designed in order to achieve this aim. In the Beta VI, the connecting curves (splines) were used instead of the four diagonal walls, while the two vertical walls remained unchanged. The Alpha VI is a step forward on the Beta VI, which was promoted by filleting all angles among the vertical walls, created arcs, and face sheets. The two offered sandwich structures have not hitherto been provided in the literature. All models were designed and simulated by the CATIA and ABAQUS, respectively. The three-dimensional printer fabricated the samples by fused deposition modeling technique. The material properties were determined under tensile, compression, and three-point bending tests. The results are carried out by two methods based on experimental tests and finite element analyses that confirmed each other. The achievements provide novel insights into the determination of the adequate number of unit cells and demonstrate the energy absorption capacity of the Beta VI and Alpha VI are 23.7% and 53.9%, respectively, higher than the out-of-plane honeycomb sandwich structures.

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An Immunoinformatics Approach for SARS-CoV-2 in Latam Populations and Multi-Epitope Vaccine Candidate Directed Towards the World’s Population

Vaccines ◽

10.3390/vaccines9060581 ◽

2021 ◽

Vol 9 (6) ◽

pp. 581

Author(s):

Andrés Felipe Cuspoca ◽

Laura Lorena Díaz ◽

Alvaro Fernando Acosta ◽

Marcela Katherine Peñaloza ◽

Yardany Rafael Méndez ◽

...

Keyword(s):

B Lymphocyte ◽

Three Dimensional ◽

Experimental Tests ◽

Health Crisis ◽

Public Health Crisis ◽

Histocompatibility Complex ◽

Potential Vaccine ◽

Lymphocyte Responses ◽

Socioeconomic Consequences ◽

Epitope Candidate

The coronavirus pandemic is a major public health crisis affecting global health systems with dire socioeconomic consequences, especially in vulnerable regions such as Latin America (LATAM). There is an urgent need for a vaccine to help control contagion, reduce mortality and alleviate social costs. In this study, we propose a rational multi-epitope candidate vaccine against SARS-CoV-2. Using bioinformatics, we constructed a library of potential vaccine peptides, based on the affinity of the most common major human histocompatibility complex (HLA) I and II molecules in the LATAM population to predict immunological complexes among antigenic, non-toxic and non-allergenic peptides extracted from the conserved regions of 92 proteomes. Although HLA-C, had the greatest antigenic peptide capacity from SARS-CoV-2, HLA-B and HLA-A, could be more relevant based on COVID-19 risk of infection in LATAM countries. We also used three-dimensional structures of SARS-CoV-2 proteins to identify potential regions for antibody production. The best HLA-I and II predictions (with increased coverage in common alleles and regions evoking B lymphocyte responses) were grouped into an optimized final multi-epitope construct containing the adjuvants Beta defensin-3, TpD, and PADRE, which are recognized for invoking a safe and specific immune response. Finally, we used Molecular Dynamics to identify the multi-epitope construct which may be a stable target for TLR-4/MD-2. This would prove to be safe and provide the physicochemical requirements for conducting experimental tests around the world.

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On the Post-Processing of 3D-Printed ABS Parts

Polymers ◽

10.3390/polym13101559 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1559

Author(s):

Mohammad Reza Khosravani ◽

Jonas Schüürmann ◽

Filippo Berto ◽

Tamara Reinicke

Keyword(s):

Surface Treatment ◽

Fused Deposition Modeling ◽

Three Dimensional ◽

Acrylonitrile Butadiene Styrene ◽

Experimental Tests ◽

Fracture Load ◽

Post Processing ◽

Fused Deposition ◽

Dog Bone ◽

3D Printed

Application of Additive Manufacturing (AM) has significantly increased in the past few years. AM also known as three-dimensional (3D) printing has been currently used in fabrication of prototypes and end-use products. Considering the new applications of additively manufactured components, it is necessary to study structural details of these parts. In the current study, influence of a post-processing on the mechanical properties of 3D-printed parts has been investigated. To this aim, Acrylonitrile Butadiene Styrene (ABS) material was used to produce test coupons based on the Fused Deposition Modeling (FDM) process. More in deep, a device was designed and fabricated to fix imperfection and provide smooth surfaces on the 3D-printed ABS specimens. Later, original and treated specimens were subjected to a series of tensile loads, three-point bending tests, and water absorption tests. The experimental tests indicated fracture load in untreated dog-bone shaped specimen was 2026.1 N which was decreased to 1951.7 N after surface treatment. Moreover, the performed surface treatment was lead and decrease in tensile strength from 29.37 MPa to 26.25 MPa. Comparison of the results confirmed effects of the surface modification on the fracture toughness of the examined semi-circular bending components. Moreover, a 3D laser microscope was used for visual investigation of the specimens. The documented results are beneficial for next designs and optimization of finishing processes.

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Numerical Analysis of the Perforated Steel Sheets Under Uni-Axial Tensile Force

Metals ◽

10.3390/met9060632 ◽

2019 ◽

Vol 9 (6) ◽

pp. 632 ◽

Cited By ~ 1

Author(s):

Ahmed M. Sayed

Keyword(s):

Load Capacity ◽

Tensile Force ◽

Three Dimensional ◽

Tensile Load ◽

Experimental Tests ◽

Strain Engineering ◽

Uniaxial Tensile ◽

Fe Model ◽

Stress Strain ◽

Steel Sheets

The perforated steel sheets have many uses, so they should be studied under the influence of the uniaxial tensile load. The presence of these holes in the steel sheets certainly affects the mechanical properties. This paper aims at studying the behavior of the stress-strain engineering relationships of the perforated steel sheets. To achieve this, the three-dimensional finite element (FE) model is mainly designed to investigate the effect of this condition. Experimental tests were carried out on solid specimens to be used in the test of model accuracy of the FE simulation. Simulation testing shows that the FE modeling revealed the ability to calculate the stress-strain engineering relationships of perforated steel sheets. It can be concluded that the effect of a perforated rhombus shape is greater than the others, and perforated square shape has no effect on the stress-strain engineering relationships. The efficiency of the perforated staggered or linearly distribution shapes with the actual net area on the applied loads has the opposite effect, as it reduces the load capacity for all types of perforated shapes. Despite the decrease in load capacity, it improves the properties of the steel sheets.

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Bending response of carbon fiber composite sandwich beams with three dimensional honeycomb cores

Composite Structures ◽

10.1016/j.compstruct.2013.09.035 ◽

2014 ◽

Vol 108 ◽

pp. 234-242 ◽

Cited By ~ 54

Author(s):

Jian Xiong ◽

Li Ma ◽

Ariel Stocchi ◽

Jinshui Yang ◽

Linzhi Wu ◽

...

Keyword(s):

Carbon Fiber ◽

Fiber Composite ◽

Three Dimensional ◽

Sandwich Beams ◽

Carbon Fiber Composite ◽

Composite Sandwich ◽

Honeycomb Cores ◽

Bending Response

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An Equivalent-Plane Cross-Coupling Position Control for Contour-Accuracy Improvement in Three-Axis Free-Form Contour Following Tasks

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4042027 ◽

2018 ◽

Vol 141 (4) ◽

Author(s):

Jian-Wei Ma ◽

De-Ning Song ◽

Zhen-Yuan Jia ◽

Wen-Wen Jiang ◽

Fu-Ji Wang ◽

...

Keyword(s):

Error Control ◽

Position Control ◽

Three Dimensional ◽

Cross Coupling ◽

Experimental Tests ◽

Numerical Control ◽

Free Form ◽

Contouring Error ◽

Contour Following ◽

Better Than

To reduce the contouring errors in computer-numerical-control (CNC) contour-following tasks, the cross-coupling controller (CCC) is widely researched and used. However, most existing CCCs are well-designed for two-axis contouring and can hardly be generalized to compensate three-axis curved contour following errors. This paper proposes an equivalent-plane CCC scheme so that most of the two-axis CCCs or flexibly designed algorithms can be utilized for equal control of the three-axis contouring errors. An initial-value regeneration-based Newton method is first proposed to compute the foot point from the actual motion position to the desired contour with a high accuracy, so as to establish the equivalent plane where the estimated three-dimensional contouring-error vector is included. After that, the signed contouring error is computed in the equivalent plane, thus a typical two-axis proportional-integral-differential (PID)-based CCC is utilized for its control. Finally, the two-axis control commands generated by the typical CCC are coupled to three-axis control commands according to the geometry of the established equivalent plane. Experimental tests are conducted to verify the effectiveness of the presented method. The testing results illustrate that the proposed equivalent-plane CCC performs much better than conventional method in both error estimation and error control.

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