scholarly journals Static and Fatigue Tests on Cementitious Cantilever Beams Using Nanoindenter

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 630 ◽  
Author(s):  
Yidong Gan ◽  
Hongzhi Zhang ◽  
Branko Šavija ◽  
Erik Schlangen ◽  
Klaas van Breugel
Keyword(s):  
Cement Paste ◽  
Fracture Behaviour ◽  
Test Procedure ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Cantilever Beams ◽  
Fundamental Properties ◽  
Micromechanical Properties ◽  
Preliminary Study ◽  
Binding Component

Cement paste is the main binding component in concrete and thus its fundamental properties are of great significance for understanding the fracture behaviour as well as the ageing process of concrete. One major aim of this paper is to characterize the micromechanical properties of cement paste with the aid of a nanoindenter. Besides, this paper also presents a preliminary study on the fatigue behaviour of cement paste at the micrometer level. Miniaturized cantilever beams made of cement paste with different water/cement ratios were statically and cyclically loaded. The micromechanical properties of cement paste were determined based on the measured load-displacement curves. The evolution of fatigue damage was evaluated in terms of the residual displacement, strength, and elastic modulus. The results show that the developed test procedure in this work is able to produce reliable micromechanical properties of cement paste. In addition, little damage was observed in the cantilever beams under the applied stress level of 50% to 70% for 1000 loading cycles. This work may shed some light on studying the fatigue behaviour of concrete in a multiscale manner.

Elevated Temperature Fatigue Fracture Behaviour of Aluminium Alloy Subjected to Spectrum Loadings

2012 ◽  
Vol 165 ◽  
pp. 219-223
Author(s):  
K.A. Zakaria ◽  
S. Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
C.H. Azhari
Keyword(s):  
Aluminium Alloy ◽  
Fatigue Fracture ◽  
Elevated Temperatures ◽  
Fatigue Testing ◽  
Fracture Behaviour ◽  
Testing Machine ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Engine Mount ◽  
Load Sequence

This paper discusses the fatigue fracture behaviour of aluminium alloy AA6061-T6 under spectrum loadings at room and elevated temperatures. The load sequence can have a very significant effect in fatigue lives and normally the fatigue strength of material decrease with increasing temperature. In this study, variable amplitude loading (VAL) signal was obtained from the engine mount bracket of an automobile in a normal driving condition. Constant amplitude loading (CAL), high to low and low to high spectrum loadings were then derived from the VAL obtained from the data capturing process to study the fatigue behaviour that subjected to spectrum loadings at the room and elevated temperatures. The fatigue tests were performed according to an ASTM E466 standard using a servo-hydraulic fatigue testing machine. Fatigue fracture surfaces were then sectioned and inspected by employing a high magnification microscope. Results indicated that fracture surface behaviours of specimens were influenced significantly by the load sequence and temperatures, which can be related to the fatigue lives of aluminium alloy under spectrum loadings.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

A Reliability-Based Approach to Assess Fatigue Behaviour Based on Small Incomplete Data Sets

2008 ◽  
Vol 44-46 ◽  
pp. 871-878 ◽  
Author(s):  
Chu Yang Luo ◽  
Jun Jiang Xiong ◽  
R.A. Shenoi
Keyword(s):  
Incomplete Data ◽  
Standard Procedure ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Small Sample ◽  
Data Sets ◽  
Safe Life ◽  
A New Technique ◽  
And Performance

This paper outlines a new technique to address the paucity of data in determining fatigue life and performance based on reliability concepts. Two new randomized models are presented for estimating the safe life and pS-N curve, by using the standard procedure for statistical analysis and dealing with small sample numbers of incomplete data. The confidence level formulations for the safe and p-S-N curve are also given. The concepts are then applied for the determination of the safe life and p-S-N curve. Two sets of fatigue tests for the safe life and p-S-N curve are conducted to validate the presented method, demonstrating the practical use of the proposed technique.

Effects of T5 and T6 Heat Treatments Applied to Rheocast A356 Parts for Automotive Applications

2008 ◽  
Vol 141-143 ◽  
pp. 237-242 ◽  
Author(s):  
Mario Rosso ◽  
Ildiko Peter ◽  
R. Villa
Keyword(s):  
Fatigue Behaviour ◽  
Cyclic Stress ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Controlled Cooling ◽  
Test Analysis ◽  
Heat Treated ◽  
Mechanical Performances ◽  
Semi Solid ◽  
Number Of Cycles

The correlation between the evaluation of the mechanical and of the fatigue behaviour of the rheocast, T5 and T6 heat treated SSM A356 aluminium alloy with respect to the microstructures of the component has been investigated. The study has been carried out on a suspension arm injected in a rheocasting 800 tons plant in Stampal S.p.A. The new rheocasting is a process that allows obtaining the alloys in a semisolid state directly from the liquid state, by controlled cooling of the molten alloys. The resulting microstructures are very fine, free from defects and homogeneous: these characteristics improve the mechanical properties of the alloys and specially the response to cyclic stress, an important issue for a suspension component. After a preliminary tensile test analysis, axial high frequency fatigue tests have been carried out at room temperature on specimen cut out from the suspension arm to determine the Wöhler curve and the number of cycles to failure. The results of this work allow a comparison of the effects of heat treatment process, T5 or T6, on Semi-Solid components for industrial applications in the automotive field. On the basis of these analysis the correlation between microstructure and mechanical performances can be established.

scholarly journals Effect of Carbon Nanofiber Clustering on the Micromechanical Properties of a Cement Paste

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 223
Author(s):  
Lesa Brown ◽  
Catherine S. Stephens ◽  
Paul G. Allison ◽  
Florence Sanchez
Keyword(s):  
Cement Paste ◽  
Mechanical Response ◽  
Carbon Nanofiber ◽  
Homogenization Method ◽  
Indentation Modulus ◽  
Interfacial Zone ◽  
Micromechanical Properties ◽  
Significant Interest ◽  
Low Stiffness ◽  
Portland Cement Paste

The use of carbon nanofibers (CNFs) in cement systems has received significant interest over the last decade due to their nanoscale reinforcing potential. However, despite many reports on the formation of localized CNF clusters, their effect on the cement paste micromechanical properties and relation to the mechanical response at the macroscopic scale are still not fully understood. In this study, grid nanoindentation coupled with scanning electron microscopy and energy dispersive spectroscopy was used to determine the local elastic indentation modulus and hardness of a portland cement paste containing 0.2% CNFs with sub-micro and microscale CNF clusters. The presence of low stiffness and porous assemblage of phases (modulus of 15–25 GPa) was identified in the cement paste with CNFs and was attributed primarily to the interfacial zone surrounding the CNF clusters. The CNFs favored the formation of higher modulus C–S–H phases (>30 GPa) in the bulk paste at the expense of the lower stiffness C–S–H. Nanoindentation results combined with a microscale–macroscale upscaling homogenization method further revealed an elastic modulus of the CNF clusters in the range from 18 to 21 GPa, indicating that the CNF clusters acted as compliant inclusions relative to the cement paste.

Fatigue Behaviour of DLC Coated Al 7075-T6 Alloy in an Aggressive Mixture

2014 ◽  
Vol 627 ◽  
pp. 81-84 ◽  
Author(s):  
Sergio Baragetti ◽  
Riccardo Gerosa ◽  
Francesco Villa
Keyword(s):  
High Performance ◽  
Contact Fatigue ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Structural Elements ◽  
Pvd Coatings ◽  
Bending Fatigue ◽  
Al 7075 ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

7075-T6 aluminium alloy is commonly adopted in high performance structures and components. Its fatigue behaviour is however dramatically worsened by exposure to aggressive environments. The deposition of PVD coatings, which are commonly adopted to increase the surface properties of structural elements in terms of hardness, contact fatigue and wear resistance, could be beneficial also for the fatigue behaviour of a 7075-T6 substrate in an aggressive environment. In the present work, Diamond Like Carbon (DLC) PVD coated 7075-T6 specimens immersed in methanol have been analysed, by means of step-loading rotating bending fatigue tests (R = -1) at 2·105 cycles. Coated specimens were tested in laboratory air for comparison, and uncoated polished samples were studied in both the environments to obtain reference values. SEM micrographs of the fracture surfaces were taken to investigate the effects of the corrosive environment on the failure mechanism.

Environmental Fatigue Test of CF8M With a Small Autoclave Simulating PWR Conditions

2008 ◽  
Author(s):  
Il-Seok Jeong ◽  
Gag-Hyeon Ha ◽  
Tae-Ryoung Kim
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Test Procedure ◽  
Cyclic Strain ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Measuring Instruments ◽  
Pressurized Water Reactor ◽  
Pressurized Water

To develop a fatigue design curve of cast stainless steel CF8M used in primary piping material of nuclear power plants, low-cycle fatigue tests have been conducted by Korea Electric Power Research Institute (KEPRI). A small autoclave simulated the environment of a pressurized water reactor (PWR), 15 MPa and 315 °C. Fatigue life was measured in terms of the number of cycles with the variation of strain amplitudes at 0.04%/s strain rate. A small autoclave of 1 liter and cylindrical solid fatigue specimens were used for the strain-controlled low cycle environmental fatigue tests to make the experiments convenient. However, it was difficult to install displacement measuring instruments at the target length of the specimens inside the autoclave. To mitigate the difficulty displacement data measured at the shoulders of the specimen were calibrated based on the data relation of the target and shoulder length of the specimen during hot air test conditions. KEPRI developed a test procedure to perform low cycle environmental fatigue tests in the small autoclave. The procedure corrects the cyclic strain hardening effect by performing additional tests in high temperature air condition. KEPRI verified that the corrected test result agreed well with that of finite element method analysis. The process of correcting environmental fatigue data would be useful for producing reliable fatigue curves using a small autoclave simulating the operating conditions of a PWR.

scholarly journals Fatigue behaviour of open-hole samples and automotive mini-structures made of woven glass-fibre-reinforced polyamide 6,6

2018 ◽  
Vol 165 ◽  
pp. 07007
Author(s):  
Amélie Malpot ◽  
Fabienne Touchard ◽  
Sébastien Bergamo ◽  
Catherine Peyrac ◽  
Richard Montaudon ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Thermoplastic Composite ◽  
Semiempirical Model ◽  
Open Hole ◽  
Automotive Parts ◽  
Glass Fibre Reinforced ◽  
Semi Empirical ◽  
Non Destructive

In the automotive industry, the integration of thermoplastic composite components represents a high-potential solution to the mass reduction challenge. In this study, a woven glassfibre-reinforced composite with a polyamide 6,6 matrix is considered for the purpose of being integrated into automotive parts. Tension-tension fatigue tests were conducted on [(0/90)3] openhole samples. These tests were instrumented with non-destructive techniques, namely acoustic emission and infrared thermography. Acoustic emission results showed fibre-matrix debonding and fibre breakages in open-hole samples, located around the hole. Furthermore, 3-point bending fatigue tests were performed on “omega” mini-structures. A semi-empirical model was used in order to predict the fatigue lives of both open-hole coupons and automotive mini-structures. Predictions of the model for open-holes samples underestimate experimental fatigue lives. Nevertheless, the semiempirical model showed good results for the fatigue life prediction of composite mini-structures.

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