Papers by Keyword: Compression Test

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Authors: Bao Long Shen, Chun Tao Chang, Akihisa Inoue
Authors: Mishel Weschler, Aurora Antoniac, Danut Cojocaru, Iulian Vasile Antoniac
Abstract: The purpose of our study was to compare the mechanical properties of the different abutment under the static loading, aspect treated by many researchers [1-4], especially following the improvements given by the new proposed three-piece abutment, described below. We evaluated the effect of compression loading on the screw joint stability of the two-piece abutment and a new proposed three-piece abutment connected to an internal hexagon implant in vitro.The dental implant used was type AlphaBio SPI with an internal hexagon shape with following dimensions: length 13mm and diameter 3.75mm. The two types of abutment were used: the common type consisting of two piece straight titanium abutment and the second type consisting of three piece abutment (two titanium pieces and the third piece made of UHMWPE). For two-piece titanium implant/abutment systems with a screw-retained connection, the respective prefabricated straight abutments were tightened with a torque gauge using titanium abutment screws (type M-TLA) according to the manufacturer’s instructions. In the second case, the first titanium piece was a connector base between the implant and the UHMWPE abutment body which is assembled all together with the implant abutment fixation screw. The experimental systems were positioned in bovine cortical bone with a central hole (3.75 mm in diameter), and mechanical characteristics were evaluated using mechanical tensile tests. The mechanical tensile tests were carried out using INSTRON 3382 tensile test equipment. All tensile tests were performed at a constant strain rate of 1mm/min until a maximum elongation of 4mm. Stress-strain tensile curves were obtained for each experimental system.There were significant differences in the case of using the system with three piece abutment and we could conclude that this type of abutment assure a lower pressing on the entire system due to the shock absorbent properties of the piece made by UHMWPE.
Authors: Eun Suk Choi, Jung Woo Lee, Chang Joh, Jong Won Kwark, Jee Sang Kim, Yoon Seok Choi
Abstract: In the application of Ultra High Performance Concrete (UHPC) to PSC girders by using the post-tensioning system, the high strength and ductility of UHPC in tension can be exploited to substitute the confined reinforcing bars which control the rupture around the anchorage device. The exploitation of such properties is expected to simplify the reinforcing details around the anchorage zone. Taking advantage of UHPC can downsize a cross section with the attributes of high compression and tensile strength. This paper reports the local behavior of UHPC anchor block under compression. Test specimens were made based on mix proportion of K-UHPC (KICT-Ultra High Performance Concrete) developed by the Korea Institute of Construction Technology (KICT). The performance of the anchor block was evaluated according to ETAG-013 (European Technical Agreement Guide No.13) of EOTA (European Organization for Technical Approvals). As the results of the experiment, it is found that the details and reinforcement of UHPC anchorage zone can be simplified with the interconnection effect and the high intensity of the matrix itself.
Authors: Wen Wen Peng, Wei Dong Zeng, Qing Jiang Wang, Yan Chun Zhu
Abstract: A novel high-speed photography is introduced to determine the critical fracture strain of a near alpha titanium ally during hot compression deformation. This method precisely captures the nucleation site and propagation process of cracking, and thus is an excellent method to represent dynamically the hot-deformation fracture. Compared with the traditional way, it can significantly decrease the number of trials and improve the accuracy. Based on this method, the critical fracture strain is measured, and a critical fracture model is developed.
Authors: C. Mahesh, Anindya Deb, S.V. Kailas, C. Uma Shankar, T.R.G. Kutty, K.N. Mahule
Abstract: The characterization of a closed-cell aluminum foam with the trade name Alporas is carried out here under compression loading for a nominal cross-head speed of 1 mm/min. Foam samples in the form of cubes are tested in a UTM and the average stress-strain behavior is obtained which clearly displays a plateau strength of approximately 2 MPa. It is noted that the specific energy absorption capacity of the foam can be high despite its low strength which makes it attractive as a material for certain energy-absorbing countermeasures. The mechanical behavior of the present Alporas foam is simulated using cellular (i.e. so-called microstructure-based) and solid element-based finite element models. The efficacy of the cellular approach is shown, perhaps for the first time in published literature, in terms of prediction of both stress-strain response and inclined fold formation during axial crush under compression loading. Keeping in mind future applications under impact loads, limited results are presented when foam samples are subjected to low velocity impact in a drop-weight test set-up.
Authors: Hee Jae Shin, Lee Ku Kwac, Sun Ho Ko, Tae Hoon Kim, Hong Gun Kim
Abstract: Of the advanced composite materials for aerospace structures such as aircrafts and space devices, the carbon fiber reinforced plastics (CFRP) is applied to many sectors that require lightweight materials for its high strength and stiffness. One of the disadvantages of the CFRP, however, is that it is weak against impact. In this study, impact test specimens were manufactured with five fiber stacking angles (0°/0°, 0°/15°, 0°/30°, 0°/45°, 0°/90°) according to ASTM D7136[15], and a falling weight test was performed to analyze the correlation between their mechanical and thermal characteristics. As a result, the impact energy applied to the five test specimens with different fiber stacking angles was almost constant at 30.63 J - 30.78 J. The absorbed energy increased with the increase in the fiber stacking angle, and decreased after 0°/45°. The average temperature on the fractured surface increased with the increase in the fiber stacking angle in all specimens other than the 0°/0° specimen.
Authors: Ying Tong, Guo Zheng Quan, Gang Luo, Jie Zhou
Abstract: This work was focused on the compressive deformation behavior of 42CrMo steel at temperatures from 1123K to 1348K and strain rates from 0.01s-1 to 10s-1 on a Gleeble-1500 thermo-simulation machine. The true stress-strain curves tested exhibit peak stresses at small strains, after them the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. And the stress level decreases with increasing deformation temperature and decreasing strain rate. The values of strain hardening exponent n, and the strain rate sensitivity exponent m were calculated the method of multiple linear regression, the results show that the two material parameters are not constants, but changes with temperature and strain rate. Then the two variable material parameters were introduced into Fields-Backofen equation amended. Thus the constitutive mechanical discription of 42CrMo steel which can accurately describe the relationships among flow stress, temperature, strain rate, strain offers the basic model for plastic forming process simulation.
Authors: Ji Lin Yu, Er Heng Wang, Liu Wei Guo
Abstract: The phenomenological constitutive framework for compressible elasto-plastic solids presented by Chen and Lu [1] is extended to the dynamic cases by assuming that the material parameter curves in the stress potential depend also on the strain rate. To check the applicability of the extended model, three types of dynamic experiments, i.e., uniaxial compression, lateral-constrained compression and side-constrained compression tests, are conducted for an open-cell aluminum foam at different strain rates. The first two types of dynamic tests are used as characteristic tests to determine the material parameter curves at different strain rates which are then used to construct the stress potential function in the model. The results show that the stress-strain curves under side-constrained compression predicted by the model are in agreement with those obtained experimentally.
Authors: Chao Lu, Peng Ding, Zheng Hua Chen
Abstract: In this paper, we use acoustic emission (AE) system to collect the AE signals and analyze the damage evolution during the monotonic compression test. Based on the experimental correlation diagram of the load and characters of the acoustic emission, the reference load of failure was found. The experimental results also revealed the characters of the source of the acoustic emission signals after the wavelet packet decomposition and frequency spectrum analysis. The frequency range of the matrix cracking is on the range of 125~187.5 kHz, while the frequency range of layer debonding is wide, it is not just on the low-frequency range but on the high-frequency range. The frequency of fiber breakage is on the high frequency range, nearly on the range of 375~437.5 kHz.
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