Determination of the fatigue life of plastics from the self-heating temperature

1970 ◽  
Vol 3 (1) ◽  
pp. 78-81 ◽  
Author(s):  
P. P. Oldyrev
2011 ◽  
Vol 20 (5) ◽  
pp. 096369351102000 ◽  
Author(s):  
Andrzej Katunin

The present study is focused on the analytical modelling of the stationary self-heating caused by the hysteretic behaviour of the polymeric laminated circular and annular plates hinged on the boundary under axisymmetric transverse cyclic loading. The investigation was based on the complex parameters concept. The coupled thermoviscoelasticity problem was solved by substitution of the dissipation energy function to the heat transfer equation as a source function. The self-heating temperature distributions formulas were obtained by solving the heat transfer equation with appropriate thermal boundary conditions using trigonometric Fourier series. Numerous parametric analyses were presented. It was shown, that omitting the influence of the self-heating effect may results in the incorrect description of the behaviour of polymeric composites under cyclic loading.


2018 ◽  
Vol 165 ◽  
pp. 22022
Author(s):  
Vincent Roué ◽  
Cédric Doudard ◽  
Sylvain Calloch ◽  
Frédéric Montel ◽  
Quentin Pujol D’Andrebo ◽  
...  

The determination of high cycle fatigue (HCF) properties of a material with standard method requires a lot of specimens, and could be really time consuming. The self-heating method has been developed in order to predict S–N–P curves (i.e., amplitude stress – number of cycles to failure – probability of failure) with only a few specimens. So the time-saving advantage of this method has been demonstrated on several materials, at room temperature. In order to reduce the cost and time of fatigue characterization at high temperature, the self-heating method is adapted to characterize HCF properties of a titanium alloy, the Ti-6Al-4V (TA6V), at different temperatures. So the self-heating procedure is adjusted to conduct tests with a furnace. Two dissipative phenomena can be observed on self-heating curves. Because of this, a two-scale probabilistic model with two dissipative mechanisms is used to describe them. The first one is observed for low amplitudes of cyclic loading, under the fatigue limit, and the second one for higher amplitudes where the mechanisms of fatigue damage are activated and are dissipating more energy. This model was developed on steel at room temperature. Even so, it is used to describe the self-heating curves of the TA6V at several temperatures.


2012 ◽  
Vol 21 (3) ◽  
pp. 096369351202100 ◽  
Author(s):  
Andrzej Katunin ◽  
Marek Fidali

In the presented study the experimental results for the investigation of fatigue of polymeric composites subjected to intensive cyclic loading with presence of the self-heating effect were presented. Experiments were carried out on laboratory stand, which provides the synchronous measurement of loading force, displacements and temperature. It was observed, that the fatigue process during occurrence of the self-heating effect consists of three phases, which were analyzed and described. The characteristic self-heating temperature distributions and their evolution during the whole loading history were analyzed. The parametric analysis of influence of loading conditions on the self-heating temperature evolution and fatigue of polymeric composites was presented. Basing upon the measurement results the authors proposed empirical models, which give a qualitative evaluation of parametric dependencies.


2018 ◽  
Vol 18 (1) ◽  
pp. 5-12 ◽  
Author(s):  
A. Katunin

AbstractSince self-heating effect may significantly intensify structural degradation, it is essential to investigate its criticality, i.e. the temperature value at which fatigue fracture is initiated. In this paper, a new and sensitive criticality indicator based on evaluation of evolution of surface temperature distribution was proposed and experimentally validated. It was shown that comparing to other measurement techniques the presented approach allows for precise evaluation of the critical value of the self-heating temperature. The properly determined critical value may be helpful both during design and operation of elements made of polymers and polymeric composite.


2012 ◽  
Vol 730-732 ◽  
pp. 853-858
Author(s):  
Vicenç Torra ◽  
Carlota Auguet ◽  
Antonio Isalgue ◽  
Guillem Carreras ◽  
Francisco C. Lovey

The main interest focuses in the necessary tools for accurate simulation of the damper behavior in their application. It’s essential a well determined knowledge of the dissipated energy and of the hysteresis cycle shape for a correct simulation. The self-heating effects and the coupling between hysteresis and the relevant temperature effects associated to continuous cycling were studied. In particular, the experimental analysis concentrates in the action of cycling frequency on the hysteresis width and on the dissipated energy. The external and the self-heating temperature effects were studied. In particular, the convective actions of cooling in the conditioned air were visualized. The study of self-heating actions at extremely slow cycles, built by strain steps, shows minor latent heat dissipations in the entire sample. For trained samples, the temperature measurements establish that the transformation is “distributed” not “localized” in the complete sample.


2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
O. V. Malyshkina ◽  
Anton Yurievich Eliseev ◽  
R. M. Grechishkin

The influence of the switching processes on self-heating of ferroelectric PZT ceramics samples was studied in high-amplitude sine and meander electric fields in a wide frequency range of 50 to 1500 Hz. It is shown that the linear dependence of the self-heating temperature on the electric field frequency is observed only in low-frequency region. It was found that there exists a maximum on the frequency dependence of the self-heating temperature. The critical frequency fcr corresponding to this maximum depends on both the properties of the material and geometry of the sample.


Author(s):  
Б. А. Бондарев ◽  
П. В. Комаров ◽  
А. В. Ерофеев ◽  
В. А. Баязов

Постановка задачи. Для определения выносливости полимерных композиционных материалов используют различные методы ускоренных испытаний. Одним из таких методов является температурный, который имеет свои ограничения применения. Это подразумевает необходимость установления возможности его применения для эпоксидных полимерных материалов. Результаты. Предложена формула для определения величины усталостной долговечности эпоксидного композиционного материала, опытным путем установлена достоверность величин, рассчитываемых по данной формуле. Доказано, что интенсивность роста температуры зависит от скорости загружения. Выводы. Достоверность расчетов по предложенной формуле для расчета показателей усталостной долговечности подтверждена сравнением результатов с опытными данными, значения достаточно близко коррелируют, что позволяет применять эту формулу при расчете выносливости для образцов из эпоксидного композита. Statement of the problem. Various methods of accelerated testing are used to determine the endurance of polymer composite materials. One of these methods is the temperature method which has its own limitations of application. Thus the possibility of its application for epoxy polymer materials should be established. Results. The article proposes a formula for identifying the value of the fatigue life of an epoxy composite material. The reliability of the values calculated using this formula is experimentally established. It is proved that the intensity of the temperature increase depends on the loading speed. Conclusions. The reliability of the calculations according to the proposed formula for calculating the fatigue life indicators is confirmed by comparing the results with experimental data, the values are quite closely correlated, which allows us to use this formula when calculating the endurance for samples made of epoxy composite.


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