Study on mechanical properties of welded structures in ultra-low temperature environment based on DIC

2020 ◽  
Author(s):  
Jiangfan Zhou ◽  
Yunquan SU ◽  
Guoliang XU ◽  
Xiaolei BA ◽  
Tairan WANG ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Welded Structures ◽  
Temperature Environment

scholarly journals Analysis of Mechanical Properties and Mechanism of Natural Rubber Waterstop after Aging in Low-Temperature Environment

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2119
Author(s):  
Lin Yu ◽  
Shiman Liu ◽  
Weiwei Yang ◽  
Mengying Liu
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Energy Dispersive Spectrometry ◽  
Permanent Deformation ◽  
Test Chamber ◽  
Accelerate Aging ◽  
Aging Mechanism ◽  
Temperature Environment ◽  
Freezing Test ◽  
Temperature Water

In order to elucidate the aging performance and aging mechanism of a rubber waterstop in low-temperature environments, the rubber waterstops were placed in the freezing test chamber to accelerate aging, and then we tested its tensile strength, elongation, tear strength, compression permanent deformation and hardness at different times. Additionally, the damaged specimens were tested by scanning electron microscope, Fourier transform infrared spectroscopy and energy dispersive spectrometry. The results showed that with the growth of aging time, the mechanical properties of the rubber waterstop are reduced. At the same time, many protrusions appeared on the surface of the rubber waterstop, the C element gradually decreased, and the O element gradually increased. During the period of 72–90 days, the content of the C element in the low-temperature air environment significantly decreased compared with that in low-temperature water, while the content of O element increased significantly.

Mechanical properties of an epoxy-based adhesive under high strain rate loadings at low temperature environment

2016 ◽  
Vol 105 ◽  
pp. 132-137 ◽  
Author(s):  
Zhemin Jia ◽  
David Hui ◽  
Guoqing Yuan ◽  
John Lair ◽  
Kin-tak Lau ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Temperature Environment

scholarly journals Research on Performance Test System of Space Harmonic Reducer in High Vacuum and Low Temperature Environment

Machines ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Jing Wang ◽  
Zhihua Wan ◽  
Zhurong Dong ◽  
Zhengguo Li
Keyword(s):  
Low Temperature ◽  
High Speed ◽  
Performance Test ◽  
High Reliability ◽  
High Vacuum ◽  
Test System ◽  
Low Noise ◽  
Speed Ratio ◽  
Space Harmonic ◽  
Temperature Environment

The harmonic reducer, with its advantages of high precision, low noise, light weight, and high speed ratio, has been widely used in aerospace solar wing deployment mechanisms, antenna pointing mechanisms, robot joints, and other precision transmission fields. Accurately predicting the performance of the harmonic reducer under various application conditions is of great significance to the high reliability and long life of the harmonic reducer. In this paper, a set of automatic harmonic reducer performance test systems is designed. By using the CANOpen bus interface to control the servo motor as the drive motor, through accurately controlling the motor speed and rotation angle, collecting the angle, torque, and current in real time, the life cycle test of space harmonic reducer was carried out in high vacuum and low temperature environment on the ground. Then, the collected data were automatically analyzed and calculated. The test data of the transmission accuracy, backlash, and transmission efficiency of the space harmonic reducer were obtained. It is proven by experiments that the performance data of the harmonic reducer in space work can be more accurately obtained by using the test system mentioned in this paper, which is convenient for further research on related lubricating materials.

scholarly journals Low-Temperature Mechanical Properties of High-Density and Low-Density Polyethylene and Their Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1821
Author(s):  
Ildar I. Salakhov ◽  
Nadim M. Shaidullin ◽  
Anatoly E. Chalykh ◽  
Mikhail A. Matsko ◽  
Alexey V. Shapagin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Impact Strength ◽  
Relative Elongation ◽  
High Density ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Elongation At Break ◽  
Subzero Temperatures ◽  
Izod Impact

Low-temperature properties of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and their blends were studied. The analyzed low-temperature mechanical properties involve the deformation resistance and impact strength characteristics. HDPE is a bimodal ethylene/1-hexene copolymer; LDPE is a branched ethylene homopolymer containing short-chain branches of different length; LLDPE is a binary ethylene/1-butene copolymer and an ethylene/1-butene/1-hexene terpolymer. The samples of copolymers and their blends were studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), 13С NMR spectroscopy, and dynamic mechanical analysis (DMA) using testing machines equipped with a cryochamber. It is proposed that such parameters as “relative elongation at break at −45 °C” and “Izod impact strength at −40 °C” are used instead of the ductile-to-brittle transition temperature to assess frost resistance properties because these parameters are more sensitive to deformation and impact at subzero temperatures for HDPE. LLDPE is shown to exhibit higher relative elongation at break at −45 °C and Izod impact strength at −20 ÷ 60 °C compared to those of LDPE. LLDPE terpolymer added to HDPE (at a content ≥ 25 wt.%) simultaneously increases flow properties and improves tensile properties of the blend at −45 °C. Changes in low-temperature properties as a function of molecular weight, MWD, crystallinity, and branch content were determined for HDPE, LLDPE, and their blends. The DMA data prove the resulting dependences. The reported findings allow one to understand and predict mechanical properties in the HDPE–LLDPE systems at subzero temperatures.

scholarly journals Effects of equal channel angular pressing and heat treatments on the microstructures and mechanical properties of selective laser melted and cast AlSi10Mg alloys

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Przemysław Snopiński ◽  
Mariusz Król ◽  
Marek Pagáč ◽  
Jana Petrů ◽  
Jiří Hajnyš ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Heat Treatments ◽  
Electron Backscattered Diffraction ◽  
Angular Pressing ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Before And After ◽  
The Impact

AbstractThis study investigated the impact of the equal channel angular pressing (ECAP) combined with heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys fabricated via selective laser melting (SLM) and gravity casting. Special attention was directed towards determining the effect of post-fabrication heat treatments on the microstructural evolution of AlSi10Mg alloy fabricated using two different routes. Three initial alloy conditions were considered prior to ECAP deformation: (1) as-cast in solution treated (T4) condition, (2) SLM in T4 condition, (3) SLM subjected to low-temperature annealing. Light microscopy, transmission electron microscopy, X-ray diffraction line broadening analysis, and electron backscattered diffraction analysis were used to characterize the microstructures before and after ECAP. The results indicated that SLM followed by low-temperature annealing led to superior mechanical properties, relative to the two other conditions. Microscopic analyses revealed that the partial-cellular structure contributed to strong work hardening. This behavior enhanced the material’s strength because of the enhanced accumulation of geometrically necessary dislocations during ECAP deformation.

scholarly journals Interfacial Reactions and Mechanical Properties of Sn–58Bi Solder Joints with Ag Nanoparticles Prepared Using Ultra-Fast Laser Bonding

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 335
Author(s):  
Gyuwon Jeong ◽  
Dong-Yurl Yu ◽  
Seongju Baek ◽  
Junghwan Bang ◽  
Tae-Ik Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Printed Circuit Boards ◽  
Solder Joints ◽  
Interfacial Reactions ◽  
Circuit Boards ◽  
Ag Nps ◽  
Laser Bonding ◽  
Laser Soldering ◽  
Low Temperature Bonding

The effects of Ag nanoparticle (Ag NP) addition on interfacial reaction and mechanical properties of Sn–58Bi solder joints using ultra-fast laser soldering were investigated. Laser-assisted low-temperature bonding was used to solder Sn–58Bi based pastes, with different Ag NP contents, onto organic surface preservative-finished Cu pads of printed circuit boards. The solder joints after laser bonding were examined to determine the effects of Ag NPs on interfacial reactions and intermetallic compounds (IMCs) and high-temperature storage tests performed to investigate its effects on the long-term reliabilities of solder joints. Their mechanical properties were also assessed using shear tests. Although the bonding time of the laser process was shorter than that of a conventional reflow process, Cu–Sn IMCs, such as Cu6Sn5 and Cu3Sn, were well formed at the interface of the solder joint. The addition of Ag NPs also improved the mechanical properties of the solder joints by reducing brittle fracture and suppressing IMC growth. However, excessive addition of Ag NPs degraded the mechanical properties due to coarsened Ag3Sn IMCs. Thus, this research predicts that the laser bonding process can be applied to low-temperature bonding to reduce thermal damage and improve the mechanical properties of Sn–58Bi solders, whose microstructure and related mechanical properties can be improved by adding optimal amounts of Ag NPs.

scholarly journals Experimental Study of Low Temperature Performance of Porous Asphalt Mixture

2021 ◽  
Vol 11 (9) ◽  
pp. 4029
Author(s):  
Jian Wang ◽  
Pui-Lam Ng ◽  
Yuhua Gong ◽  
Han Su ◽  
Jinsheng Du
Keyword(s):  
Low Temperature ◽  
Test Temperature ◽  
Asphalt Mixture ◽  
Aging Condition ◽  
Porous Asphalt ◽  
Bending Strain ◽  
Temperature Performance ◽  
Temperature Environment ◽  
Modifier Content ◽  
Low Temperature Performance

Porous asphalt mixture can be used as a road surface paving material with the remarkable advantage to prevent water accumulation and ponding. However, the performance of porous asphalt mixture in low temperature environment has not been thoroughly investigated, and this forms the subject of research in the present study. The mineral aggregate gradation of porous asphalt mixture was designed based on Bailey method, and the low temperature performance of porous asphalt mixture was studied by means of the low temperature bending test. The factors affecting the low temperature performance of porous asphalt mixture were analyzed through the orthogonal experimental design method, and the effects of porosity, modifier content, aging condition, and test temperature on the low temperature performance of porous asphalt mixture were evaluated. The results showed that the modifier content was the most important factor affecting the low temperature performance of porous asphalt mixture, followed by the test temperature, while the porosity and the aging condition were the least. Among the three performance evaluation indicators, namely the flexural tensile strength, maximum bending strain, and bending stiffness modulus, the maximum bending strain had the highest sensitivity to the porosity. It can be seen from the single factor influence test of porosity that there existed an approximately linear relationship between the maximum bending strain and the porosity of porous asphalt mixture, and the maximum bending strain decreased with increasing porosity. Furthermore, in order to ensure the good working performance of porous asphalt mixture in low temperature environment, the porosity should also satisfy the required limits of the maximum bending strain.

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