scholarly journals Fatigue Behaviour of Textile Reinforced Cementitious Composites and Their Application in Sandwich Elements

2019 ◽  
Vol 9 (7) ◽  
pp. 1293 ◽  
Author(s):  
Matthias De Munck ◽  
Tine Tysmans ◽  
Jan Wastiels ◽  
Panagiotis Kapsalis ◽  
Jolien Vervloet ◽  
...  

Using large lightweight insulating sandwich panels with cement composite faces offers great possibilities for the renovation of existing dwellings. During their lifetime, these panels are subjected to wind loading, which is equivalent to a repeated loading. To guarantee the structural performance of these panels during their entire lifetime, it is necessary to quantify the impact of these loading conditions on the long term. The fatigue behaviour was, therefore, examined in this paper both at the material level of the faces and at the element level as well. plain textile reinforced cementitious composite (TRC) specimens were subjected to 100,000 loading cycles by means of a uniaxial tensile test, while sandwich beams were loaded 100.000 times with a four-point bending test. Results show that the residual behaviour is strongly dependent on the occurrence of cracks. The formation of cracks leads to a reduction of the initial stiffness. The ultimate strength is only affected in a minor way by the preloading history.

2019 ◽  
pp. 089270571986827 ◽  
Author(s):  
Nayan Pundhir ◽  
Sunny Zafar ◽  
Himanshu Pathak

The present work deals with the microwave-assisted compression moulding of high-density polyethylene (HDPE)-based composites. In the present work, 20 wt% of reinforcement in the form of kenaf and multi-walled carbon nanotube (MWCNT) was used to fabricate HDPE/kenaf and HDPE/MWCNT polymer composites. The mechanical characterizations of the microwave-processed composites were carried out in terms of uniaxial tensile test with different strain rate, multistep stress relaxation, flexural and impact test. The uniaxial tensile test revealed that the tensile modulus of microwave-processed four-layered HDPE/kenaf polymer composite was 35.2% higher than that of HDPE/MWCNT polymer composite. The HDPE/MWCNT polymer composite showed a minimum of 1.25 GPa and a maximum of 4.7 GPa of elastic modulus when tested at different strain rate. The impact energy absorbed by the HDPE/kenaf polymer composite (1.055 J) was 81.12% higher than the HDPE/MWCNT polymer composite (0.582 J).


Author(s):  
Jorge de Andres ◽  
Michael D. Jones ◽  
Catrin M. Davies

Abstract A new technique has recently been proposed to provide improved estimates of the creep contribution to the crack mouth opening displacements (CMOD) and displacement rates during creep crack growth (CCG) tests. This technique employs finite element analysis that incorporates material specific uniaxial tensile test data to simulate crack growth in an experimental test and can account for strain history and creep stress relaxation effects during CCG tests. In this work, this new methodology is applied to analyse the results of a CCG test performed on a relatively low constraint single edge notched tension, SEN(T), geometry. The proportions of the CMOD due to elasticity and plasticity are quantified, and compared to historic, standardised methods of estimating these values. The new method reduces the over estimation of the contribution of plasticity to the CMOD measurement. The impact of this analysis on CCG test results is discussed.


Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2929
Author(s):  
Andrzej Kubit ◽  
Tomasz Trzepieciński ◽  
Bogdan Krasowski ◽  
Ján Slota ◽  
Emil Spišák

This paper presents a new product, a glass laminate aluminium-reinforced epoxy (GLARE)-based thin-walled structure with a stiffener in the form of a longitudinal rib. The stiffening rib in an outer metallic layer of a GLARE-based panel was fabricated by the incremental sheet forming technique and Alclad 2024-T3 aluminium alloy sheets were used as adherends. The strength properties of the adhesive joint between the layers of the fibre metal laminates (FMLs) were determined in a uniaxial tensile test, peel drum test, tensile/shear test and short-beam three-point-bending test. Two variants of FMLs were considered, with an adhesive film and without an adhesive film between the adherends and the epoxy/glass prepreg. The FMLs were tested at three different temperatures that corresponded to those found under real aircraft operating conditions, i.e., −60 °C, room temperature and +80 °C. It was found that the temperatures do not affect the tensile strength and shear strength of the FMLs tested. However, there was a noticeable increase in the stiffness of samples stretched at reduced temperature. An additional adhesive film layer between the adherends and the glass/epoxy prepreg significantly improves the static peeling strength of the joint both at reduced and at elevated temperatures. A clear increase in the critical force at which buckling occurs has been clearly demonstrated in the uniaxial compression test of GLARE-based rib-stiffened panels. In the case of GLARE-based rib-stiffened panels, the critical force averaged 15,370 N, while for the non-embossed variant, it was 11,430 N, which translates into a 34.5% increase in critical force.


2020 ◽  
Vol 1012 ◽  
pp. 349-353
Author(s):  
D.B. Colaço ◽  
M.A. Ribeiro ◽  
T.M. Maciel ◽  
R.H.F. de Melo

The demand for lighter materials with suitable mechanical properties and a high resistance to corrosion has been increasing in the industries. Therefore, aluminum appears as an alternative due to its set of properties. The aim of this work was to evaluate residual stress levels and mechanical properties of welded joints of Aluminum-Magnesium alloy AA 5083-O using the Friction Stir Welding process. For mechanical characterization were performed a uniaxial tensile test, Vickers hardness, bending test and, finally, the determination of residual stresses. It was concluded that welding by FSW process with an angle of inclination of the tool at 3o, established better results due to better mixing of materials. The best results of tensile strength and a lower level of residual stresses were obtained using a tool rotation speed of 340 RPM with welding advance speed of 180 mm/min and 70 mm/min.


2009 ◽  
Vol 23 (06n07) ◽  
pp. 1885-1890 ◽  
Author(s):  
ZUOCHENG WANG ◽  
GUOTAO CUI ◽  
TAO SUN ◽  
WEIMIN GUO ◽  
XIULING ZHAO ◽  
...  

In our research, boron was added into the Nb -added high strength low alloy (HSLA) H -section steels. The contents of boron added were 4ppm, 8ppm and 11ppm, respectively. The mechanical properties of H -section steels with/without boron were examined by using uniaxial tensile test and Charpy impact test ( V -notch). The morphologies of the microstructure and the fracture surfaces of the impact specimens were observed by metalloscope, stereomicroscope and electron probe. The experimental results indicate that boron gives a significant increase in impact toughness, especially in low temperature impact toughness, though it leads to an unremarkable increase in strength and plasticity. For instance, the absorbed energy at -40°C reaches up to 126J from 15J by 8ppm boron addition, and the ductile-brittle transition temperature declines by 20°C. It is shown that boron has a beneficial effect on grain refinement. The fracture mechanism is transited from cleavage fracture to dimple fracture due to boron addition.


2011 ◽  
Vol 250-253 ◽  
pp. 765-768
Author(s):  
Wen Ling Tian ◽  
Lei Xu ◽  
Xiao Wei Wang

For the compressive strength of the normal concrete is high and the tensile strength is low, it is typically brittle material. The ultimate tensile elongation of it is insufficiently 1/1000. Zhongwei Wu, an academician of Chinese Academy of Engineering pointed out that compounding cementitious composites was the way to make it high-performance, and fiber reinforced was the key[1]. Polyvinyl Alcohol Engineered Cementitious Composites has super flexural performance[2] and stretching ability[3],and its ultimate deflection is approximately 40 times larger than that of normal concrete when bended, similar to the multiple cracking and super toughness of uniaxial tensile test, it shows significant bending hardening behavior in the process of the test. This paper studied its flexural property by four point bending test .


Author(s):  
Xiaodong Zhang ◽  
Shuguang Liu ◽  
Changwang Yan ◽  
Xiaoxiao Wang ◽  
Huiwen Wang

The purpose of this study was to conduct laboratory test programs on how much vehicle-induced vibrations during early ages affected the tensile performance of Polyvinyl alcohol-engineering cementitious composites (PVA-ECC). A self-improved device was used to simulate the vehicle-induced vibrations, and after vibrating with the designed variables, both a uniaxial tensile test and a grey correlation analysis were performed. The results indicated that: the effects of vehicle-induced vibrations on the tensile performance of early age PVA-ECC were significant, and they generally tended to be negative in this investigation. In particular, for all of the vibrated PVA-ECC specimens, the most negative age when vibrated occurred during the period between the initial set and the final set. In this period, the effects of the vibration duration on the tensile performance of the PVA-ECC tended to be negative overall, but the impact trend and the degree varied for the corresponding lengths of duration and levels of frequency. The cracking strength was the most sensitive to the variables in this investigation, and then it followed the ultimate tensile strength and strain. The grey correlation analysis was applicable in analyzing the effects of vehicle-induced vibrations on the tensile performance of early age PVA-ECC.


Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
G. Behera ◽  
Kamal Sharma ◽  
R. K. Singh

Miniature disk bending test is used to evaluate the mechanical behavior of irradiated materials and its properties — mainly ductility loss due to irradiation in steel. In Miniature Disk Bending Machine the specimen is firmly held between the two horizontal jaws of punch, and an indentor with spherical ball travels vertically. Researchers have observed reasonable correlations between values of the yield stress, strain hardening and ultimate tensile strength estimated from this test and mechanical properties determined from the uniaxial tensile test. Some methods for the analysis of miniature disk bending, proposed by various authors have been discussed in the paper. It is difficult to distinguish between the regimes of elastic and plastic deformation since local plastic deformation occurs for very small values of load when the magnitude of spatially averaged stress will be well below the yield stress. Also, the analytical solution for large amplitude, plastic deformation becomes rather unwieldy. Hence a finite element analysis has been carried out. The finite element model, considers contact between the indentor and test specimen, friction between various pairs of surfaces and elastic plastic behavior. The load is increased in steps and converged solution has been obtained and analysis terminated at a load beyond which a stable solution cannot be obtained. A sensitivity study has been carried out by varying the various parameters defining the material properties by ±10% around the base values. This study has been carried out to generate a data base for the load-deflection characteristics of similar materials from which the material properties can be evaluated by an inverse calculation. It is seen that the deflection obtained by analytical elastic bending theory is significantly lower than that obtained by the elasto-plastic finite element solution at relatively small values of load. The FE solution and experimental results are in reasonably good agreement.


2021 ◽  
Vol 12 (2) ◽  
pp. 103
Author(s):  
Sudarsono Sudarsono ◽  
Hidayat Hidayat ◽  
Aminur Aminur ◽  
Sarwo Pranoto ◽  
Prinob Aksar

Welding is one of the methods widely used in the joining of metals for structural elements. One of the factors that influence the strength of welded metals is types of welding joints. Suitability of the type of welding joint with geometries of base metals is required to obtain welded metal products with optimum properties. In this study an attempt is made to investigate mechanical properties of welded metals with two different types of joints (single-V and double-V) using the shielded metal arc welding (SMAW) process. Low carbon steel with bevel angle of 60° was used in this study. Welding process was performed using current of 70 A with a constant welding speed. The flexural properties and uniaxial tensile properties are studied by three-point bending test and uniaxial tensile test respectively. Test results show that the tensile strength and the bending strength of single-V specimens is 521.64 N/mm2 and 525.11 N/mm2 respectively. In addition, the tensile strength and the bending strength of double-V specimens is 517.33 N/mm2 and  504.24 N/mm2 respectively


2016 ◽  
Vol 08 (05) ◽  
pp. 1650066 ◽  
Author(s):  
Serena de Gelidi ◽  
Gianluca Tozzi ◽  
Andrea Bucchi

Rubber-like materials as many soft tissues can be described as incompressible and hyper-elastic materials. Their comparable elastic behavior, up to a certain extent, has been exploited to develop and test experimental methodologies to be then applied to soft biological tissues such as aortic wall. Hence, theoretical and experimental simulation of aortic tissue, and more generally blood vessel tissue, has been often conducted using rubbers. Despite all the efforts in characterizing such materials, a clear and comprehensive testing procedure is still missing. In particular, the influence of pre-conditioning in the mechanical response of hyper-elastic materials has been often neglected. In this paper, the importance of pre-conditioning is demonstrated by: (i) exploring the effect of stretching frequency applied before the uniaxial tensile test; (ii) recognizing the role of specimen geometry and strain amplitude; (iii) verifying the impact of experimental data acquisition on finite element predictions. It was found that stress–strain relationship shows a statistical difference between some frequencies of pre-conditioning and its absence. Only certain pre-conditioning frequencies were able to generate repeatable experimental data for strip or dumb-bell shapes. This feature corresponds to a consistent reduction in the scatter of critical pressures obtained by numerical simulations.


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