scholarly journals Analysis of Concrete Failure on the Descending Branch of the Load-Displacement Curve

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 921
Author(s):  
Gennadiy Kolesnikov
Keyword(s):  
Uniaxial Compression ◽  
Modulus Of Elasticity ◽  
Stress And Strain ◽  
Displacement Curve ◽  
Compression Tests ◽  
Three Point Bending ◽  
Effective Stresses ◽  
Concrete Failure ◽  
Load Displacement ◽  
Displacement Diagram

In this paper, load-displacement and stress-strain diagrams are considered for the uniaxial compression of concrete and under three-point bending. It is known that the destruction of such materials occurs on the descending branch of the load-displacement diagram. The attention of the presented research is focused on the explanation of this phenomenon. Fracture mechanics approaches are used as a research tool. The method for determining effective stresses and modulus of elasticity of concrete based on the results of uniaxial compression tests has been substantiated. The ratios necessary for the calculation were obtained without any assumptions about the reinforcement of concrete and the mechanical properties of its components. However, the effect of these properties is considered indirectly, using the stress and strain peaks determined by standard concrete compression tests. It was found that the effective stresses increase both on the ascending branch and on the descending branch of the load-displacement diagram. This explains the destruction of concrete on the descending branch of the load-displacement diagram. The results of determining the stresses and modulus of elasticity under uniaxial compression are comparable with the results obtained in experiments known in the literature.

scholarly journals Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2312
Author(s):  
Xin Liang ◽  
Fang Yan ◽  
Yuliang Chen ◽  
Huiqin Wu ◽  
Peihuan Ye ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Force ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Displacement Curve ◽  
Direct Shear ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Concrete Failure ◽  
Load Displacement

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

scholarly journals Investigation on the behavior of rigid polyvinylchloride pipes subjected to uniaxial compression loads

2017 ◽  
Vol 23 (3) ◽  
pp. 145
Author(s):  
Abdullah Ali Nasser Alhamati ◽  
Abdul Halim Ghazali ◽  
Jamalodin Norzaie
Keyword(s):  
Uniaxial Compression ◽  
Small Diameter ◽  
Experimental Tests ◽  
Displacement Curve ◽  
Axial Loads ◽  
Pipe System ◽  
Euler Buckling ◽  
Specimen Height ◽  
Brick Element ◽  
Load Displacement

The objective of this research was to investigate the capability of rigid Polyvinylchloride (PVC-U) pipes to sustain axial loads. The behavior of PVC-U pipes specimens subjected to short-term uniaxial compression loads were experimentally investigated. Results of the load-displacement tests on pipes of different wall thickness, diameter, and specimen heights were recorded. The experimental test results show that the PVC-U pipes are capable of supporting loads greater than the required design load (3.4 kN). Increasing the pipe specimen height decreases the pipe strength for supporting the axial loads.  Euler buckling was observed in the pipe specimens with small diameter and long axial height. Furthermore, an attempt has been made to utilize the ANSYS finite element commercial package to model the pipe system using eight noded brick element and the results were compared with those obtained from the experimental tests. Good agreement was found between the two sets of results, within the elastic range of the load-displacement curve.

scholarly journals Evaluation of remodeling and geometry on the biomechanical properties of nacreous bivalve shells

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Estefano Muñoz-Moya ◽  
Claudio M. García-Herrera ◽  
Nelson A. Lagos ◽  
Aldo F. Abarca-Ortega ◽  
Antonio G. Checa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Uniaxial Compression ◽  
Shell Length ◽  
Biomechanical Properties ◽  
Material Behavior ◽  
Stress And Strain ◽  
Wave Forces ◽  
Compression Tests ◽  
Shell Size

AbstractMollusks have developed a broad diversity of shelled structures to protect against challenges imposed by biological interactions(e.g., predation) and constraints (e.g., $$pCO_2$$ p C O 2 -induced ocean acidification and wave-forces). Although the study of shell biomechanical properties with nacreous microstructure has provided understanding about the role of shell integrity and functionality on mollusk performance and survival, there are no studies, to our knowledge, that delve into the variability of these properties during the mollusk ontogeny, between both shells of bivalves or across the shell length. In this study, using as a model the intertidal mussel Perumytilus purpuratus to obtain, for the first time, the mechanical properties of its shells with nacreous microstructure; we perform uniaxial compression tests oriented in three orthogonal axes corresponding to the orthotropic directions of the shell material behavior (thickness, longitudinal, and transversal). Thus, we evaluated whether the shell material’s stress and strain strength and elastic modulus showed differences in mechanical behavior in mussels of different sizes, between valves, and across the shell length. Our results showed that the biomechanical properties of the material building the P. purpuratus shells are symmetrical in both valves and homogeneous across the shell length. However, uniaxial compression tests performed across the shell thickness showed that biomechanical performance depends on the shell size (aging); and that mechanical properties such as the elastic modulus, maximum stress, and strain become degraded during ontogeny. SEM observations evidenced that compression induced a tortuous fracture with a delamination effect on the aragonite mineralogical structure of the shell. Findings suggest that P. purpuratus may become vulnerable to durophagous predators and wave forces in older stages, with implications in mussel beds ecology and biodiversity of intertidal habitats.

Predicting Fracture Toughness of Three-Point Bending Specimen from Tensile Test Based on Micro-Plastic Damage Model

2011 ◽  
Vol 228-229 ◽  
pp. 345-350 ◽  
Author(s):  
Bin Wang ◽  
Chao Ma ◽  
Peng Wang
Keyword(s):  
Fracture Toughness ◽  
Damage Model ◽  
Tension Test ◽  
Bending Test ◽  
Test Material ◽  
Displacement Curve ◽  
Resistance Curve ◽  
Three Point Bending ◽  
Plastic Damage ◽  
Load Displacement

In this research X65 steel is chosen as the test material, and tension test and three-point bending test of X65 are made, then we got the load - displacement curve and the resistance curve. Using the finite element method to derive load - displacement curves of tension test based on the micro-plastic damage model, and the parameters controlling ductile crack growth are gotten by compared with the test results. We obtained the resistance curve of numerical calculation by WARP3D based on the parameters, which in good agreement with the experimental results. The results indicate that the three-point bending fracture toughness can be predicted by tension test based on micro-plastic damage mechanism.

scholarly journals Investigation of Microcrack Propagation and Energy Evolution in Brittle Rocks Based on the Voronoi Model

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2108
Author(s):  
Guanlin Liu ◽  
Youliang Chen ◽  
Xi Du ◽  
Peng Xiao ◽  
Shaoming Liao ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Damage Evolution ◽  
Rock Sample ◽  
Rock Fracture ◽  
Damage Threshold ◽  
Crack Development ◽  
Energy Evolution ◽  
Shear Cracks ◽  
Compression Tests ◽  
Microcrack Propagation

The cracking of rock mass under compression is the main factor causing structural failure. Therefore, it is very crucial to establish a rock damage evolution model to investigate the crack development process and reveal the failure and instability mechanism of rock under load. In this study, four different strength types of rock samples from hard to weak were selected, and the Voronoi method was used to perform and analyze uniaxial compression tests and the fracture process. The change characteristics of the number, angle, and length of cracks in the process of rock failure and instability were obtained. Three laws of crack development, damage evolution, and energy evolution were analyzed. The main conclusions are as follows. (1) The rock’s initial damage is mainly caused by tensile cracks, and the rapid growth of shear cracks after exceeding the damage threshold indicates that the rock is about to be a failure. The development of micro-cracks is mainly concentrated on the diagonal of the rock sample and gradually expands to the middle along the two ends of the diagonal. (2) The identification point of failure precursor information in Acoustic Emission (AE) can effectively provide a safety warning for the development of rock fracture. (3) The uniaxial compression damage constitutive equation of the rock sample with the crack length as the parameter is established, which can better reflect the damage evolution characteristics of the rock sample. (4) Tensile crack requires low energy consumption and energy dispersion is not concentrated. The damage is not apparent. Shear cracks are concentrated and consume a large amount of energy, resulting in strong damage and making it easy to form macro-cracks.

scholarly journals Load Distribution on PET-G 3D Prints of Honeycomb Cellular Structures under Compression Load

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1983
Author(s):  
Olimpia Basurto-Vázquez ◽  
Elvia P. Sánchez-Rodríguez ◽  
Graham J. McShane ◽  
Dora I. Medina
Keyword(s):  
Fused Deposition Modeling ◽  
Structural Characteristics ◽  
Honeycomb Structure ◽  
Cellular Structures ◽  
Displacement Curve ◽  
Compression Tests ◽  
Compression Load ◽  
Fused Deposition ◽  
3D Printed ◽  
Printing Direction

Energy resulting from an impact is manifested through unwanted damage to objects or persons. New materials made of cellular structures have enhanced energy absorption (EA) capabilities. The hexagonal honeycomb is widely known for its space-filling capacity, structural stability, and high EA potential. Additive manufacturing (AM) technologies have been effectively useful in a vast range of applications. The evolution of these technologies has been studied continuously, with a focus on improving the mechanical and structural characteristics of three-dimensional (3D)-printed models to create complex quality parts that satisfy design and mechanical requirements. In this study, 3D honeycomb structures of novel material polyethylene terephthalate glycol (PET-G) were fabricated by the fused deposition modeling (FDM) method with different infill density values (30%, 70%, and 100%) and printing orientations (edge, flat, and upright). The effectiveness for EA of the design and the effect of the process parameters of infill density and layer printing orientation were investigated by performing in-plane compression tests, and the set of parameters that produced superior results for better EA was determined by analyzing the area under the curve and the welding between the filament layers in the printed object via FDM. The results showed that the printing parameters implemented in this study considerably affected the mechanical properties of the 3D-printed PET-G honeycomb structure. The structure with the upright printing direction and 100% infill density exhibited an extension to delamination and fragmentation, thus, a desirable performance with a long plateau region in the load–displacement curve and major absorption of energy.

A novel method to determine critical CTOA directly by load-displacement curve

2020 ◽  
Vol 230 ◽  
pp. 107013
Author(s):  
Ying Zhen ◽  
Xuyang Li ◽  
Yuguang Cao ◽  
Shihua Zhang
Keyword(s):  
Displacement Curve ◽  
Novel Method ◽  
Load Displacement

Effect of Phase Transformation on the Wear Behavior of NiTi Alloy

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
M. Abedini ◽  
H. M. Ghasemi ◽  
M. Nili Ahmadabadi ◽  
R. Mahmudi
Keyword(s):  
Wear Behavior ◽  
Niti Alloy ◽  
Testing Temperature ◽  
Compression Tests ◽  
Scanning Calorimetry ◽  
Three Point Bending ◽  
Mechanical And Tribological Properties ◽  
Ni Alloy ◽  
Shape Memory Effects ◽  
Pin On Disk

In this paper, mechanical and tribological properties of a Ti-50.3 at % Ni alloy were investigated. The transformation temperatures of the alloy were determined using differential scanning calorimetry. Three-point bending tests were performed to characterize the pseudoelasticity and shape memory effects. Uni-axial compression tests were also performed at different testing temperatures. The wear tests were conducted using a pin-on-disk tribometer at testing temperatures ranging from 0°C to 80°C. The wear results showed that with increasing the testing temperature from 0°C to 50°C, the wear of the alloy was decreased, which could be attributed to the higher pseudoelasticity of the alloy at a testing temperature of 50°C. The pseudoelasticity of the alloy decreased at a higher testing temperature of 80°C; however, its wear resistance increased considerably due to higher ultimate strength and work hardening.

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