Temperature-dependent ratcheting of PTFE gaskets under cyclic compressive loads with small stress amplitude

Zheng, Xiaotao; Xiang, Wen; Gao, Jiuyang; Yu, Jiuyang; Wang, Lin; Xu, Jianmin

doi:10.1016/j.polymertesting.2016.12.002

Cited by 25 publications

(8 citation statements)

References 19 publications

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“…Concretely, the peak strain is 48.99% at the first cycle, whereas it is 49.81% at the 2000th cycle. Actually, the accumulated strain with small stress amplitude may be impacted by the creep effect . Therefore, the creep strains of type 3865 specimen with the same peak stress of 32 MPa at 500°C and 600°C are further tested, as shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…Under practical operating conditions, gaskets are usually subjected to repeated compressive loads with small or great stress amplitudes because of the randomness of vibrations, pressure or temperature fluctuations, start‐up or shut‐down processes, and so on . In these cases, the accumulated deformation of RGSWSSI usually occurs, which is essential to evaluate the sealing performance of joints, especially at elevated temperatures …”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

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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“…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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“…17 Lu et al 12 performed ratcheting tests on polycarbonate polymers and showed great dependency of ratcheting deformation on the loading spectrum. The influence of molecular weight on ratcheting response of polycarbonate polymer samples was further studied by Xi et al 13 Temperature-dependent compressive ratcheting deformation of polytetrafluoroethylene (PTFE) was confirmed by Zheng et al 14 Kang and coworkers 15 examined glass fiber reinforced polyester resin under various asymmetric stress histories with various stress rates and peak stress hold to examine the ratchetting evolution of the continuous and short glass fiber reinforced resin matrix composites. They reported that as glass fiber volume fraction increased, both ratchetting deformation time-dependency response diminished.…”

Section: Introductionmentioning

confidence: 99%

Ratcheting response of nylon fiber reinforced natural rubber/styrene butadiene rubber composites under uniaxial stress cycles: Experimental studies

Vahidifar

Esmizadeh

Naderi

et al. 2017

Fatigue Fract Eng Mat Struct

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The present study intends to study the ratcheting response of nylon fiber reinforced natural rubber (NR)‐styrene butadiene rubber (SBR) composite samples under asymmetric stress cycles. Uniaxial tests conducted on composite samples have shown how influential the weight fraction of short nylon fibers on the stress‐strain curves/loops under monotonic and cyclic loads is. NR/SBR composite samples with various fiber contents of 0, 10, 20, 30, and 40 per hundred rubber (phr) were tested under asymmetric stress cycles. In these tests, stress‐strain hysteresis loops were progressively shifted over stress cycles resulting in progressive plastic strain accumulation. Over stress cycles, ratcheting strain progressed within the first few cycles with a relatively high rate, and as the number of cycles increased, this rate decayed resulting in a plateau in strain accumulation (shakedown). The ratcheting strain rate and magnitude resulting in shakedown were highly affected by the nylon fiber content. The experimental observations showed that this plateau (shakedown) occurred after a number of cycles in NR/SBR composite samples where the widths of hysteresis loops stayed unchanged. Samples with no fiber and that with 10 phr fiber content possessed high ratcheting rates leading samples to failure after a few stress cycles. Fracture surfaces in these samples were further analyzed through SEM investigation.

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Temperature-dependent ratcheting of PTFE gaskets under cyclic compressive loads with small stress amplitude

Cited by 25 publications

References 19 publications

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

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

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

Ratcheting response of nylon fiber reinforced natural rubber/styrene butadiene rubber composites under uniaxial stress cycles: Experimental studies

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