Loading–Unloading Cycles of Three-Dimensional-Printed Built Bimaterial Structures With Ceramic and Elastomer

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Yi-Tang Kao ◽  
Ying Zhang ◽  
Jyhwen Wang ◽  
Bruce L. Tai
Keyword(s):  
Three Dimensional ◽  
Large Cell ◽  
Frame Structure ◽  
Maximum Deflection ◽  
Ceramic Phase ◽  
Bending Tests ◽  
Four Point Bending ◽  
Previous Cycle ◽  
Bimaterial Structure ◽  
Nonlinearly Elastic

This paper studies the loading–unloading behaviors of a three-dimensional (3D)-printing built bimaterial structure consisting of an open-cellular plaster frame filled with silicone. The combination of the plaster (ceramic phase) and silicone (elastomer phase) is hypothesized to possess a nonlinearly elastic property and a better ductility. Four-point bending tests with programmed cycles of preceding deformations were conducted. The results show that there exists a linear–nonlinear transition when the bending deflection is around 2 mm in the first cycle bending. As the cycle proceeds, this linear–nonlinear transition is found at the maximum deflection of the previous cycle; meanwhile, the bending stiffness degrades. It is believed that the occurrence of microcracks inside the plaster frame is the mechanism behind the phenomenon. The silicone provides a strong network suppressing the abrupt crack propagation in a brittle material. The effects of the frame structure and plaster–silicone ratio were also compared. A high plaster content and large cell size tend to have a higher stiffness and obvious linear to nonlinear transition while it also has more significant stiffness degradation.

Loading-Unloading Cycles of 3D-Printing Built Bi-Material Structures With Ceramic and Elastomer

2016 ◽  
Author(s):  
Yi-Tang Kao ◽  
Ying Zhang ◽  
Jyhwen Wang ◽  
Bruce L. Tai
Keyword(s):  
3D Printing ◽  
Large Cell ◽  
Frame Structure ◽  
Bending Test ◽  
Material Structure ◽  
Ceramic Phase ◽  
Four Point Bending ◽  
Previous Cycle ◽  
Micro Cracks ◽  
Four Point Bending Test

This paper studies the loading-unloading behaviors of a 3D-printing built bi-material structure consisting of an open-cellular plaster frame filled with silicone. The combination of the plaster (ceramic phase) and silicone (elastomer phase) is hypothesized to possess a non-linearly elastic property and a better ductility. Four-point bending test with programmed cycles of preceding deformations was conducted. The results show that there exists a linear-nonlinear transition when the bending deflection is around 2 mm in the first cycle bending. As the cycle proceeds, this transition is found at the maximum deflection of the previous cycle; meanwhile, the bending stiffness degrades. It is believed that the occurrence of micro-cracks inside the plaster frame is the mechanism behind the phenomenon. The ductile silicone provides a strong network suppressing the abrupt crack propagation in a brittle material. The effects of the frame structure and plaster-silicone ratio were also compared. A high plaster content and large cell size tend to have a higher stiffness and obvious linear to non-linear transition while it also has more significant stiffness degradation.

Failure Behavior of Carbon Steel Pipe Having Local Wall Thinning Near Tee Joint

2006 ◽  
Author(s):  
Kotoji Ando ◽  
Koji Takahashi ◽  
Masakazu Hisatsune ◽  
Kunio Hasegawa
Keyword(s):  
Finite Element Method ◽  
Three Dimensional ◽  
Metal Loss ◽  
Failure Behavior ◽  
Fracture Type ◽  
Bending Tests ◽  
Four Point Bending ◽  
Wall Thinning ◽  
Erosion Corrosion ◽  
Local Wall Thinning

Monotonic four-point bending tests were conducted using tee pipe specimens having local wall thinning. The effects of local wall thinning on the failure behaviors of tee pipes were investigated. Local wall thinning was machined on the inside of pipes in order to simulate erosion/corrosion metal loss. The configurations of the eroded area were l = 100 mm in eroded axial length, d/t = 0.5 and 0.8 in eroded ratio, and 2θ = 90° and 180° in eroded angle. The area undergoing local wall thinning was subjected to tensile stress. It was found that fracture type could be classified into ovalization or crack initiation, depending on eroded ratio. Three-dimensional elasto-plastic analyses were also carried out using finite element method to discuss the effects of position and geometries of wall thinning in both tee pipes and straight pipes.

Fracture and Deformation Behaviors of Tee Pipe With Local Wall Thinning Under Monotonic Bending

2004 ◽  
Author(s):  
Koji Takahashi ◽  
Kotoji Ando ◽  
Masakazu Hisatsune ◽  
Kunio Hasegawa
Keyword(s):  
Three Dimensional ◽  
Local Buckling ◽  
Metal Loss ◽  
The Finite Element Method ◽  
Bending Tests ◽  
Four Point Bending ◽  
Wall Thinning ◽  
Fracture Behaviors ◽  
Deformation Behaviors ◽  
Local Wall Thinning

Monotonic four-point bending tests were conducted using tee pipe specimens having local wall thinning. The effects of local wall thinning on the fracture behaviors of tee pipes were investigated. Local wall thinning was machined on the inside of pipes in order to simulate erosion/corrosion metal loss. The configurations of the eroded area were l = 100 mm in eroded axial length, d/t = 0.5 and 0.8 in eroded ratio, and 2θ = 90° in eroded angle. The area undergoing local wall thinning was subjected to either tensile or compressive stress. Fracture behaviors of the tee pipes were compared with those of straight pipes. It was found that fracture type could be classified into ovalization, local buckling, and crack initiation, depending on pipe shape, eroded ratio, and stress at the eroded area. Three-dimensional elasto-plastic analyses were also carried out using the finite element method, which is able to accurately simulate fracture behaviors.

Delayed Photoactivation of Dual-cure Composites: Effect on Cuspal Flexure, Depth-of-cure, and Mechanical Properties

2019 ◽  
Vol 44 (2) ◽  
pp. E97-E104 ◽  
Author(s):  
KO Hughes ◽  
KJ Powell ◽  
AE Hill ◽  
D Tantbirojn ◽  
A Versluis
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Degree Of Cure ◽  
Bending Tests ◽  
Depth Of Cure ◽  
Four Point Bending ◽  
Tooth Surfaces

SUMMARY Objectives: This study tested whether delayed photoactivation could reduce shrinkage stresses in dual-cure composites and how it affected the depth-of-cure and mechanical properties. Methods and Materials: Two dual-cure composites (ACTIVA and Bulk EZ) were subjected to two polymerization protocols: photoactivation at 45 seconds (immediate) or 165 seconds (2 minutes delayed) after extrusion. Typodont premolars with standardized preparations were restored with the composites, and cuspal flexure caused by polymerization shrinkage was determined with three-dimensional scanning of the external tooth surfaces before restoration (baseline) and at 10 minutes and one hour after photoactivation. Bond integrity (intact interface) was verified with dye penetration. Depth-of-cure was determined by measuring Vickers hardness through the depth at 1-mm increments. Elastic modulus and maximum stress were determined by four-point bending tests (n=10). Results were analyzed with two- or three-way analysis of variance and pairwise comparisons (Bonferroni; α=0.05). Results: Delayed photoactivation significantly reduced cuspal flexure for both composites at 10 minutes and one hour (p≤0.003). Interface was >99% intact in every group. Depth-of-cure, elastic modulus, and flexural strength were not significantly different between the immediate and delayed photoactivation (p>0.05). The hardness of ACTIVA reduced significantly with depth (p<0.001), whereas the hardness of Bulk EZ was constant throughout the depth (p=0.942). Conclusions: Delayed photoactivation of dual-cure restorative composites can reduce shrinkage stresses without negatively affecting the degree-of-cure or mechanical properties (elastic modulus and flexural strength).

scholarly journals Analysis of the robustness of a steel frame structure with composite floors subject to multiple fire scenarios

2021 ◽  
pp. 136943322199249
Author(s):  
Riza Suwondo ◽  
Lee Cunningham ◽  
Martin Gillie ◽  
Colin Bailey
Keyword(s):  
Progressive Collapse ◽  
Three Dimensional ◽  
Steel Structure ◽  
Frame Structure ◽  
Worst Case ◽  
Collapse Resistance ◽  
Fire Scenarios ◽  
Element Approach ◽  
The One ◽  
Steel Frame Structure

This study presents robustness analyses of a three-dimensional multi-storey composite steel structure under the action of multiple fire scenarios. The main objective of the work is to improve current understanding of the collapse resistance of this type of building under different fire situations. A finite element approach was adopted with the model being firstly validated against previous studies available in the literature. The modelling approach was then used to investigate the collapse resistance of the structure for the various fire scenarios examined. Different sizes of fire compartment are considered in this study, starting from one bay, three bays and lastly the whole ground floor as the fire compartment. The investigation allows a fundamental understanding of load redistribution paths and member interactions when local failure occurs. It is concluded that the robustness of the focussed building in a fire is considerably affected by the size of fire compartments as well as fire location. The subject building can resist progressive collapse when the fire occurs only in the one-bay compartment. On the other hand, total collapse occurs when fire is located in the edge three-bay case. This shows that more than one fire scenario needs to be taken into consideration to ensure that a structure of this type can survive from collapse in the worst-case situation.

Comparison of results obtained by static 3- and 4-point bending and flexural vibration tests on solid wood, MDF, and 5-plywood

Holzforschung ◽  
2013 ◽  
Vol 67 (8) ◽  
pp. 941-948 ◽  
Author(s):  
Hiroshi Yoshihara
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Medium Density Fiberboard ◽  
Flexural Vibration ◽  
Solid Wood ◽  
Bending Tests ◽  
Four Point Bending ◽  
Flexural Vibration Test ◽  
The Difference ◽  
Vibration Tests

Abstract The flexural Young’s modulus of western hemlock, medium-density fiberboard, and 5-plywood (made of lauan) has been determined by conducting three- and four-point bending tests with various span lengths and by flexural vibration test. The Young’s modulus was significantly influenced by the deflection measurement method. In particular, the Young’s modulus was not reliable based on the difference between the deflections at two specific points in the specimen, although this test is standardized according to ISO 3349-1975 and JIS Z2101-2009.

The Influence of Static Response of Super Tall Building Mega-Frame Structure Caused by Changes of Frame Rigidities

2012 ◽  
Vol 166-169 ◽  
pp. 277-281
Author(s):  
Xiang Dong Xie ◽  
Xuan Wang ◽  
Li Qin
Keyword(s):  
Differential Equation ◽  
Analytical Approach ◽  
Three Dimensional ◽  
Tall Building ◽  
Frame Structure ◽  
Thin Wall ◽  
Static Response ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Frame Rigidity

The superstructure and its foundation of a super tall building mega-frame structure are simplified equivalently and continuously to a stiffened-thin-wall tube on semi-infinite elastic subgrade. And the influences of static response on super tall building mega-frame structure caused by changes of frame rigidity are computed and analyzed with the three-dimensional model by semi-analytical approach based on ODE(Ordinary Differential Equation) Solver, considering the interactions of subgrade, foundation and superstructure. Then some valuable conclusions are obtained through analyzing the reasonable results of the numerical example.

scholarly journals Experimental Investigations of Interactions between Sand Wave Movements, Flow Structure, and Individual Aquatic Plants in Natural Rivers: A Case Study of Potamogeton Pectinatus L.

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1166 ◽  
Author(s):  
Łukasz Przyborowski ◽  
Anna Łoboda ◽  
Robert Bialik
Keyword(s):  
Flow Velocity ◽  
Three Dimensional ◽  
Potamogeton Pectinatus ◽  
Sand Wave ◽  
Experimental Investigations ◽  
Cross Sectional ◽  
Bending Tests ◽  
Long Duration ◽  
Elevation Changes

Long-duration measurements were performed in two sandy bed rivers, and three-dimensional (3D) flow velocity and bottom elevation changes were measured in a vegetated area and in a clear region of a river. Detailed flow velocity profiles downstream and upstream of a single specimen of Potamogeton pectinatus L. were obtained and the bed morphology was assessed. Potamogeton plants gathered from each river were subjected to tensile and bending tests. The results show that the existence of the plants was influenced by both bottom and flow conditions, as the plants were located where water velocity was lower by 12% to 16% in comparison to clear region. The characteristics of the flow and sand forms depended on the cross-sectional arrangement of the river, e.g., dunes were approximately four times higher in the middle of the river than in vegetated regions near the bank. Furthermore, the studied hydrophytes were too sparse to affect water flow and had no discernible impact on the sand forms’ movements. The turbulent kinetic energy downstream of a single plant was reduced by approximately 25%. Additionally, the plants’ biomechanical characteristics and morphology were found to have adjusted to match the river conditions.

Long-Term Reliability Assessment of Bioceramics for Artificial Joints Using Microdamage Monitoring by AE

2006 ◽  
Vol 309-311 ◽  
pp. 1191-1194
Author(s):  
Shuichi Wakayama ◽  
Teppei Kawakami ◽  
Junji Ikeda
Keyword(s):  
Critical Stress ◽  
Reliability Assessment ◽  
Physiological Saline ◽  
Bending Test ◽  
Unstable Fracture ◽  
Artificial Joints ◽  
Bending Tests ◽  
Four Point Bending

Microfracture process during bending tests of alumina ceramics used for artificial joints was evaluated by acoustic emission (AE) technique. Four-point bending tests were carried out in air, refined water, physiological saline and simulated body fluid. AE behavior during bending test inhibited the rapid increasing point of AE events and energy prior to the final unstable fracture. It was understood that the bending stress at the increasing point corresponds to the critical stress for maincrack formation. The critical stress was affected by water in environments more strongly than fracture strength. Consequently, it was suggested that the characterization of maincrack formation is essential for the long-term reliability assessment of load-bearing bioceramics.

Sign in / Sign up

Export Citation Format

Share Document