Rate-dependent mechanical characteristics of polytetrafluoroethylene (PTFE) gaskets under cyclic pulsating compression

Zheng, Xiaotao; Zhang, X. H.; Wang, Lok; Wang, Lin; Yu, Jiangying; Xu, Jianmin

doi:10.1007/s00289-018-2298-x

Cited by 10 publications

(3 citation statements)

References 29 publications

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“…However, the strong CF bond energy leads PTFE has no react with any other chemical groups, which can make PTFE molecular chains slip easily. This microstructure results in lower creep resistance and high thermal expansion coefficient of PTFE . Because of this characteristic, the potential advanced applications in the field of seal engineering of neat PTFE has greatly restricted …”

Section: Introductionmentioning

confidence: 99%

Effect of tensile rates on thermal and mechanical properties of porous PTFE composites

Kou

Pan

et al. 2019

J of Applied Polymer Sci

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To achieve polymer‐matrix composites for sealing materials with thermostability and toughness, PTFE composites filled with short glass fibers (SGFs) were hyperthermal stretched to prepare a substrate material with high thermal stability and porosity. The effects of various tensile rates on the thermal and mechanical properties and morphologies were investigated. The results revealed that the thermal stability could be improved slightly and the thermal expansion coefficient of composites increased by the tensile rate. Through observing the morphologies, tensile process produced cavities and the increased tensile rate had negligible effects on porosity, which also could be proved by density test. From mechanical properties analysis, stretched composites exhibited that the tensile strength increases first and then decreases with the increased tensile rate. Although the variation tendency of Young's modulus is similar to that of tensile strength, which is smaller than that of unstretched composite. When the tensile rate reached 50 mm·min−1, the tensile strength and Young's modulus of the stretched composites increased by 65 and 9% to maximum, respectively. Meanwhile, elongation at break and shore hardness decreased. The thermal and mechanical properties improvement could be ascribed to the strain‐induced crystallization and crystal alignment. In addition, the interplanar spacing and grain size were inversely proportional to the tensile rate. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48175.

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Section: Introductionmentioning

confidence: 99%

Effect of tensile rates on thermal and mechanical properties of porous PTFE composites

Kou

Pan

et al. 2019

J of Applied Polymer Sci

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“…19(a). It is worth noting that the PTFE gasket is used in order to measure the rotation angle of flange at room temperature conveniently, and the mechanical properties of PTFE gasket are tested in detail under compression condition [30,31,32,33] . Moreover, the bolts are made by 35CrMo steel because it is one of the most widely used bolt materials in process industries [34,35] .…”

Section: Measurement Of Rotation Angles For Bolted Flange Jointsmentioning

confidence: 99%

Measurement of small rotation angle of flange joints by a novel flexure magnifying mechanism

et al. 2019

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Bolted flange joints are indispensable components in process industries due to the good sealing, assemble and disassemble capacities. Generally, the flange rigidity characterized by the rotation angle is a key index to evaluate the sealing tightness of flange joints. However, the rotation angle of flange is usually too small (less than 1º) to monitor during the assemble and operation stages. Accordingly, a novel flexure magnifying mechanism is designed to measure the small rotation angle of flange joints under internal pressure and external bending moment. The magnification factor and calculation approach of the flexure amplification mechanism are deduced and verified by experimental data and finite element simulation. Results indicate that the proposed measuring apparatus has good performance to monitor the maximum rotation angle. It is of great interest that the measured location of the maximum rotation angle is in good agreement with that in the experiment, and the average error is 7.3%, which is acceptable for practical application. Additionally, the leakage rate at the top of flange joints slowly and almost linearly increases with the increment of external bending moment ascribing to the decrease the gasket stress near the top of flange joints.

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“…The ratcheting effect is an key index to assess the shakedown behaviour of eigineering structures . Moreover, temperature‐dependent and time‐dependent ratcheting behaviours of nonmetallic material, such as PTFE, polycarbonate polymers, polyacetal, PVDF, PEEK, and nonasbestos fibre, have also been investigated widely. Recently, micromechanisms and macromechanisms of compression and recovery behaviour of flexible graphite have been investigated by Toda et al Results present that the microscopic compression/recovery behaviour of flexible graphite is impacted by the highly localized deformation of thin expanded graphite discs, while its macroscopic deformation is induced by the combined effect of bending and thickness reduction of the discs.…”

Section: Introductionmentioning

confidence: 99%

Ratcheting effect of reinforced graphite sheet with stainless steel insert (RGSWSSI) under cyclic compression at elevated temperature

Zheng

Dai

Chen

et al. 2018

Fatigue Fract Eng Mat Struct

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Ratcheting and creep of reinforced graphite sheet with stainless steel insert (RGSWSSI) are tested under cyclic stress‐controlled compression by a self‐designed clamp from 500°C to 600°C. The effects of insert type, temperature, stress amplitude, stress rate, creep, and loading sequence are considered. Results present that ratcheting deformations for RGSWSSI with 316‐L stainless steel tanged and bonded insert approach to each other and show little rate dependence, while they slightly increase with the increment of stress amplitude and temperature. Moreover, obvious ratcheting effect takes place under cyclic pulsating loads with the peak stress of 32 MPa at 500°C or higher. The accumulated deformations of RGSWSSI under small stress amplitude only increase during about the first 25 cycles and then always turn to shakedown. It can also be estimated by the corresponding static creep strain in practical engineering with good accuracy at high temperature. This work provides important data and understanding of RGSWSSI under harsh fluctuating loads.

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Rate-dependent mechanical characteristics of polytetrafluoroethylene (PTFE) gaskets under cyclic pulsating compression

Cited by 10 publications

References 29 publications

Effect of tensile rates on thermal and mechanical properties of porous PTFE composites

Effect of tensile rates on thermal and mechanical properties of porous PTFE composites

Measurement of small rotation angle of flange joints by a novel flexure magnifying mechanism

Ratcheting effect of reinforced graphite sheet with stainless steel insert (RGSWSSI) under cyclic compression at elevated temperature

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