scholarly journals Effect of Alteration on the Geochemistry and Mechanical Properties of Granite from Pingjiang, Hunan Province, China

2021 ◽  
Author(s):  
Minghao Ren ◽  
Wei Wang ◽  
Zhiquan Huang ◽  
Shanggao Li ◽  
Qi Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Hydrothermal Alteration ◽  
Trace Element Analysis ◽  
Mechanical Tests ◽  
Hydrothermal Fluids ◽  
Hunan Province ◽  
Element Analysis ◽  
Mineral Components ◽  
Low Degrees

Abstract The effect of alteration on the geochemistry and mechanical properties of granite from Pingjiang, Hunan Province, China was investigated. Six weathered and 14 hydrothermally altered samples in three footrills (PD2, PD3, and PD4) were collected for mechanical tests and major and trace element analysis. The results show that the relationship between mechanical strength and the degree of alteration, irrespective of whether this is due to weathering or hydrothermal alteration, can be described by an exponential equation. This implies that the mechanical strength decreases rapidly even at low degrees of alteration. Granite Na2O, CaO, K2O, and SiO2 contents were lowered due to weathering, whereas Fe2O3T contents increased significantly due to Fe2+ oxidation. Based on the hypothesis that Al and Zr are immobile during the hydrothermal alteration, the mobility indexes of various elements were calculated for the hydrothermally altered samples. In general, TiO2, K2O, Fe2O3T, Th, Hf, Co, Ni, and V contents were unaffected by hydrothermal alteration; Na2O, Sr, Nd, Sm, and Pb contents were lowered by hydrothermal alteration; and SiO2, Rb, Cr, U, Zn, Mn, and Cs contents were increased due to reactions with the hydrothermal fluids. Even immobile elements, such as Sm, Nd, V, and Cr, were mobilized by high-temperature hydrothermal fluids. To assess the degree of hydrothermal alteration, a new model is required that can account for the effects of the different mineral components.

scholarly journals Mechanical Response of Ni-Based CU5MCuC Alloy to Different Stabilization Thermal Treatments

2020 ◽  
Author(s):  
Andrea Gruttadauria ◽  
Silvia Barella ◽  
Claudia Fiocchi
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Mechanical Strength ◽  
Intergranular Corrosion ◽  
Mechanical Response ◽  
Annealing Treatment ◽  
Mechanical Tests ◽  
Thermal Treatments ◽  
Stabilization Treatment ◽  
Cr System

Abstract The Ni–Fe–Cr system is the basis of a series of commercial alloys featuring chemical–physical characteristics that allow them to be used in a variety of fields where excellent resistance to aggressive environments is required. In this scenario, the CU5MCuC alloy, the foundry counterpart of Alloy 825, is proving successful in the petrochemical field thanks to its good corrosion resistance in acidic and highly oxidizing environments. Intergranular corrosion resistance, critical for this material, is ensured by the stabilization treatment that allows precipitation of Nb carbides. Strengthening of this alloy takes place only via a solid solution. Therefore, its mechanical properties depend on the solution annealing treatment: often this treatment alone does not make it possible to reach the UTS imposed by the ASTM-A494 standard. In this work, the possibility of using stabilization treatment to increase mechanical strength as well was considered. Treatments, with different combinations of time and temperature, were carried out in order to modify the material’s microstructure. After the thermal treatments, microstructural analyses, mechanical tests and (pitting and intergranular) corrosion and resistance tests were carried out to identify optimal treatment parameters in order to promote the evolution of microstructural constituents capable of improving mechanical strength without decreasing corrosion resistance. The treatment that achieves the best compromise between mechanical properties and corrosion resistance is stabilization at 970 °C for 4 h.

Determination of Layer and Region Specific Mechanical Properties of Intraluminal Thrombus (ILT): The Importance of Biaxial Tensile Testing

2013 ◽  
Author(s):  
S. O’Leary ◽  
E. Kavanagh ◽  
P. Grace ◽  
T. McGloughlin ◽  
B. Doyle
Keyword(s):  
Mechanical Properties ◽  
Endovascular Aneurysm Repair ◽  
Distal Region ◽  
Mechanical Tests ◽  
Biaxial Test ◽  
Clinical Tool ◽  
Intraluminal Thrombus ◽  
Element Analysis ◽  
Aneurysm Wall

Abdominal Aortic Aneurysm (AAA) is the gradual and irreversible local widening of the distal region of the aorta. If undetected or untreated the intramural stress can exceed the strength of the aneurysm wall causing the structure to rupture. Upon rupture, AAA has a 90% mortality rate. It has been hypothesized, and shown in some studies, that regions of elevated stress of the AAA wall may be linked to sites of AAA rupture. In order for Finite Element Analysis (FEA) to be successfully used as a clinical tool, to aid in AAA rupture prediction, it is crucial that the mechanics of both the AAA wall and intraluminal thrombus (ILT) are described accurately. At present it is unclear whether ILT increases or decreases the rupture risk of AAA. This may be due to the lack of available data which can accurately describe its behaviour in vivo. A recent review of AAA mechanics explains how ‘there have been limited studies on the mechanical properties of intraluminal thrombus’. Due to the recent popularity of endovascular aneurysm repair (EVAR) the opportunities to harvest and conduct mechanical tests on this tissue are rare. This study aims to further characterize ILT using both uniaxial and biaxial test methods and where possible determine the layer and region specific mechanical properties of this material.

Straight versus modular nail: Analysis of mechanical properties two knee arthrodesis methods.

2020 ◽  
Author(s):  
Jerzy Białecki ◽  
Marcin Para ◽  
Andrzej Sobolewski ◽  
Maciej Kogut ◽  
Paweł Bartosz
Keyword(s):  
Mechanical Properties ◽  
Comparative Analysis ◽  
Mechanical Strength ◽  
Weight Bearing ◽  
Mechanical Tests ◽  
Bending Test ◽  
Implant Design ◽  
Knee Arthrodesis ◽  
Femoral Nail ◽  
Clinical Cases

Abstract Background Complications after arthroplasty often result in irreversible disability. In some cases for the extremity to be salvaged, the permanent knee joint arthrodesis is the last-chance procedure. Modular implant design simplifies surgical technique but modularity may potentially compromise mechanical strength of an implant. Mechanical properties of the implant are particularly important in case of knee arthrodesis without bone-on-bone contact where forces during gait and weight bearing are transmitted directly through the nail. The aim of this article was to perform comparative analysis of the mechanical properties of modular nail CHARFIX2 FN, when compared to the femoral nail, used for knee arthrodesis; and to analyze the effectiveness of treatment with use of this nail based on the observations of clinical cases. Methods Comparative analysis of: the static 4-point bending test, dynamic 4-point bending test and static torsion test. All tests were performed in accordance with requirements of ASTM F 1264. A clinical analysis of 5 cases, in which CHARFIX2 FN nails were used, was also performed. Results Based on the results of mechanical tests, the strength characteristics of CHARFIX2 FN nail have been found superior and more advantageous than corresponding features of the standard femoral nail. For CHARFIX2 FN nail, the median for flexural stiffness was almost 4 times higher and for maximum torque value was almost 2 times higher when compared to the femoral nail. Observations of the clinical cases gave satisfactory results. Conclusions The obtained mechanical tests present significant differences between CHARFIX2 FN and the femoral nail in mechanical strength and, therefore, its improved stability and safety for patients during walking. It can be used for permanent knee immobilization with satisfactory clinical results. The functional outcomes and subjective measurements of pain in patients treated with CHARFIX2 FN group are satisfying.

Effect of temperature on the mechanical properties of polypropylene–talc composites

2017 ◽  
Vol 31 (7) ◽  
pp. 896-912 ◽  
Author(s):  
AO Bouakkaz ◽  
A Albedah ◽  
B Bachir Bouiadjra ◽  
Sohail MA Khan ◽  
F Benyahia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Temperature Variation ◽  
Temperature Increase ◽  
Mechanical Tests ◽  
Effect Of Temperature ◽  
Dynamic Mechanical ◽  
Tensile Impact ◽  
Negative Effect ◽  
Impact Bending

In this study, the effect of the temperature and talc concentration on the mechanical properties of the polypropylene (PP) + talc composite is analysed. Tensile, impact, bending and dynamic mechanical tests were carried out to evaluate the mechanical properties of PP + talc composite and to analyse the effect of temperature variation on these properties. The obtained results show that the temperature increase has a very negative effect on the mechanical strength of the PP–talc composite but it can be significantly reduced by the augmentation of the talc content.

Thermal and Mechanical Properties of Natural Rubber/Rice Starch Interpenetrating Network Hydrogel

2013 ◽  
Vol 844 ◽  
pp. 77-80
Author(s):  
Warisada Sila-On ◽  
Jatuporn Pratoomted ◽  
Utsana Puapermpoonsiri ◽  
Chaiwute Vudjung ◽  
Wiwat Pichayakorn
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Mechanical Strength ◽  
Natural Rubber Latex ◽  
Amorphous Structure ◽  
Mechanical Tests ◽  
Rice Starch ◽  
Thermal And Mechanical Properties ◽  
Interpenetrating Networks ◽  
Scanning Calorimetry

Novel hydrogels based on natural rubber latex (NRL) and rice starch (RSt) (1:2 ratio) were prepared with various amount of N,N-methylenebisacrylamide (MBA) and 2.5 phr of maleic acid to form interpenetrating networks (IPN) using free-radical polymerization technique. The thermal and mechanical properties were performed by differential scanning calorimetry and mechanical tests. From data obtained, the change in Tg of rubber and melting point of RSt indicated that polymer-polymer interaction could be formed in IPN hydrogel. The higher amount addition of MBA created more mechanical strength of IPN hydrogels caused by the higher of interlacement formation. However, their mechanical strength of such hydrogels was lower than that of NRL alone due to the formation of amorphous structure in IPN hydrogel. These IPN hydrogels also improved the swelling property which will be utilized for wound healing application.

scholarly journals Structural Design of Mechanical Property for Biodegradable Polymeric Stent

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Yunbo Wei ◽  
Minjie Wang ◽  
Danyang Zhao ◽  
Hongxia Li ◽  
Yifei Jin
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Design Method ◽  
Ring Structure ◽  
Mechanical Tests ◽  
Radial Force ◽  
Element Analysis ◽  
Stent Expansion ◽  
Supporting Ring

How to improve stent mechanical properties is a key issue for designing biodegradable polymeric stents (BPSs). In this study, a new design method of BPS was proposed based on the force analysis of supporting rings and bridges during stent implantation, and a novel BPS called open C-shaped stent (OCS) with superior comprehensive mechanical properties was developed accordingly. The key mechanical properties including radial force, radial recoil, and axial foreshortening of the OCS have been comprehensively studied and compared with those of the Abbott BVS using finite element analysis (FEA). In addition, the effects of the stent geometries on these mechanical properties have also been discussed in detail. Besides, in vitro mechanical tests including stent expansion and planar compression experiments have been performed to verify the simulation results. Based on the FEA results, it is found that the radial force and radial recoil of the designed OCS are 30% higher and 24% lower than those of the BVS, respectively. Meanwhile, the OCS is not shortened during expansion. Radial force and radial recoil are mainly dependent on the supporting ring structure, and the utilization of designed unequal-height supporting ring (UHSR) can effectively improve these two properties. Axial foreshortening is mainly determined by the bridge geometry as well as the connecting position of the bridge with the adjacent supporting rings. It is feasible to improve the axial foreshortening by using the bridges with a curved structure and locating the connecting position in the middle of the straight section of the supporting elements. The rationality of the proposed OCS and the effectiveness of the finite element method have been verified by in vitro experiments.

scholarly journals Characterize traction–separation relation and interfacial imperfections by data-driven machine learning models

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sanjida Ferdousi ◽  
Qiyi Chen ◽  
Mehrzad Soltani ◽  
Jiadeng Zhu ◽  
Pengfei Cao ◽  
...  
Keyword(s):  
Machine Learning ◽  
Mechanical Properties ◽  
Composite Materials ◽  
Structural Reliability ◽  
Mechanical Tests ◽  
Data Driven ◽  
Gradient Boosting ◽  
Material Interfaces ◽  
Element Analysis ◽  
Extreme Gradient Boosting

AbstractInterfacial mechanical properties are important in composite materials and their applications, including vehicle structures, soft robotics, and aerospace. Determination of traction–separation (T–S) relations at interfaces in composites can lead to evaluations of structural reliability, mechanical robustness, and failures criteria. Accurate measurements on T–S relations remain challenging, since the interface interaction generally happens at microscale. With the emergence of machine learning (ML), data-driven model becomes an efficient method to predict the interfacial behaviors of composite materials and establish their mechanical models. Here, we combine ML, finite element analysis (FEA), and empirical experiments to develop data-driven models that characterize interfacial mechanical properties precisely. Specifically, eXtreme Gradient Boosting (XGBoost) multi-output regressions and classifier models are harnessed to investigate T–S relations and identify the imperfection locations at interface, respectively. The ML models are trained by macroscale force–displacement curves, which can be obtained from FEA and standard mechanical tests. The results show accurate predictions of T–S relations (R2 = 0.988) and identification of imperfection locations with 81% accuracy. Our models are experimentally validated by 3D printed double cantilever beam specimens from different materials. Furthermore, we provide a code package containing trained ML models, allowing other researchers to establish T–S relations for different material interfaces.

Effect of Pouring Temperature on Mechanical Properties and Microstructures of Aluminium Matrix Composite Strengthened by CNT with Stir Casting Method

2020 ◽  
Vol 988 ◽  
pp. 30-35
Author(s):  
Muhammad Syahid ◽  
Lukmanul H. Arma ◽  
Hairul Arsyad ◽  
Zulfikar A.R. Suwardi
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Matrix Composite ◽  
Hardness Test ◽  
Stir Casting ◽  
Mechanical Tests ◽  
Aluminium Matrix ◽  
Casting Method ◽  
Pouring Temperature ◽  
Aluminium Matrix Composite

Aluminium matrix composite reinforced Carbon nanoTubes are widely developed because it can increase mechanical strength without reducing its ductility. One of the AMC / CNT manufacturing processes is through the stir casting method. The challenge of the Al / CNT manufacturing process is the occurrence of agglomeration and CNT not homogeneous so that the right casting parameters are needed to obtain optimal results. The purpose of this study was to analyse the effect of pouring temperature on the mechanical strength and microstructure of AA6061 by adding Carbon Nanotube (CNT) through the stir casting method. The CNT is added by 0.1% wt and pouring temperature at 700 °C, 730 °C and 760 °C. Mechanical tests carried out were tensile test, hardness test, and impact test. The highest value of hardness and tensile strength was obtained at the pouring temperature of 700 °C are78 HV and 80.97 MPa. Lower pouring temperature causes smaller grain size so that it has higher strength. The distribution of hardness values ​​at the top, middle and bottom of the specimen is not evenly distributed, but does not differ greatly for all pouring temperatures. The highest value of impact strength is obtained at the pouring temperature of 760 °C which is 0.128 J/mm2. Microstructure was shown the addition of CNTs caused the size of primary silicon and aluminium grains to be small which would increase the mechanical properties.

Modification of Hypereutectic Al-20%Si Alloy by Neodymium

2015 ◽  
Vol 1095 ◽  
pp. 180-183
Author(s):  
Wei Xi Shi ◽  
Cheng Wu Du ◽  
Guang Zhe Lv ◽  
Chang Wan Liu
Keyword(s):  
Mechanical Properties ◽  
Trace Element ◽  
Base Metal ◽  
Eutectic Silicon ◽  
Trace Element Analysis ◽  
Primary Silicon ◽  
Sem Analysis ◽  
Silicon Phase ◽  
Element Analysis ◽  
Average Grain Size

The modification mechanism was studied by OM, SEM, XRD and Trace Element Analysis. The results of OM and SEM analysis show that pure Nd can effectively refine primary and eutectic silicon in hypereutectic Al-20%Si alloy. Morphology of primary silicon is transformed from pentalpha to block and the average grain size of primary silicon is reduced from 80~120μm to 20~50μm after modification. Trace Element Analysis results show that Nd can purity base metal and reduce impurity contents. XRD patterns show that no new phase formed after Nd modification. The results of mechanical properties test show that whole properties of modified sample are significantly improved. Tensile strength increases about 35.8% from 117 MPa to 148 MPa after modification, Elongation change increases about 193% from 0.56% to 1.64%. The improvement of mechanical properties should be attributed to fine primary Si phase and eutectic silicon phase and purification of base metal after modification.

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