Thermal cycling and ultraviolet radiation effects on fatigue performance of triaxial CFRP laminates for bridge applications

2021 ◽  
pp. 002199832110558
Author(s):  
Ayman Mosallam ◽  
Haohui Xin ◽  
Shaohua He ◽  
Ashraf AK Agwa ◽  
Suleyman Adanur ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Thermal Cycling ◽  
Radiation Exposure ◽  
Uv Radiation ◽  
Life Stress ◽  
Radiation Effects ◽  
Test Group ◽  
Cyclic Test ◽  
Stress Range ◽  
Thermal Cyclic Test

Environmental processing such as thermal cycling and ultraviolet (UV) exposure contributes to degradation of polymer composites mechanical properties. This study focuses on assessing fatigue life of both unstressed and stressed triaxial carbon/epoxy composite laminates exposed to both thermal cycling and UV radiation. In this study, five test series were conducted to assess such effects on fatigue life of carbon fiber reinforced polymer laminates exposed to tensile-compressive (T-C) fatigue loading. This included the following: (i) Pre-exposure (baseline) test group tests; (ii) unstressed thermal cyclic aging; (iii) stressed (tensioned) thermal cyclic test group; (iv) stressed (compressed) thermal cyclic test group; and (v) UV radiation exposure test group. Fatigue life with 95%, 97.7%, and 99% guarantee rates is calculated based on stochastic analysis. In terms of different guarantee rates, the material parameters of S-N curves are fitted after transforming the data to a log–log space. Experimental results indicated that the difference of parameter [Formula: see text] is relatively small for different guarantee rates, and that the coefficient m decreased with increasing probabilistic guarantee rate. Furthermore, the ratio [Formula: see text] decreases with larger guarantee rates and increases as the stress range increases. Results of this study indicated that UV radiation exposure has the largest effect on fatigue life stress range less than 500.0 MPa. Also, fatigue life of pre-compressed specimens exposed to thermal cyclic is most affected when exposed to stress levels larger than 500.0 MPa. For stress ranges less than 500.0 MPa, the effects on fatigue life of unstressed and pre-compressed thermal cycled specimens are relatively large as compared to baseline group.

Strahlenwirkung am Normalgewebe

2010 ◽  
Vol 49 (S 01) ◽  
pp. S53-S58 ◽  
Author(s):  
W. Dörr
Keyword(s):  
Radiation Exposure ◽  
Normal Tissue ◽  
Radiation Effects ◽  
A Priori ◽  
Cell Loss ◽  
Turnover Time ◽  
Complete Healing ◽  
Internal Radiotherapy ◽  
Normal Tissues ◽  
Chronic Radiation

SummaryThe curative effectivity of external or internal radiotherapy necessitates exposure of normal tissues with significant radiation doses, and hence must be associated with an accepted rate of side effects. These complications can not a priori be considered as an indication of a too aggressive therapy. Based on the time of first diagnosis, early (acute) and late (chronic) radiation sequelae in normal tissues can be distinguished. Early reactions per definition occur within 90 days after onset of the radiation exposure. They are based on impairment of cell production in turnover tissues, which in face of ongoing cell loss results in hypoplasia and eventually a complete loss of functional cells. The latent time is largely independent of dose and is defined by tissue biology (turnover time). Usually, complete healing of early reactions is observed. Late radiation effects can occur after symptom-free latent times of months to many years, with an inverse dependence of latency on dose. Late normal tissue changes are progressive and usually irreversible. They are based on a complex interaction of damage to various cell populations (organ parenchyma, connective tissue, capillaries), with a contribution from macrophages. Late effects are sensitive for a reduction in dose rate (recovery effects).A number of biologically based strategies for protection of normal tissues or for amelioration of radiation effects was and still is tested in experimental systems, yet, only a small fraction of these approaches has so far been introduced into clinical studies. One advantage of most of the methods is that they may be effective even if the treatment starts way after the end of radiation exposure. For a clinical exploitation, hence, the availability of early indicators for the progression of subclinical damage in the individual patient would be desirable. Moreover, there is need to further investigate the molecular pathogenesis of normal tissue effects in more detail, in order to optimise biology based preventive strategies, as well as to identify the precise mechanisms of already tested approaches (e. g. stem cells).

Morphological and Photodecomposition Rate Constant Study of PVC Films Doped with Sulfadiazine Tin(IV) Complexes

2020 ◽  
Vol 14 (2) ◽  
pp. 88
Author(s):  
Emad Yousif
Keyword(s):  
Radiation Exposure ◽  
Uv Radiation ◽  
Rate Constant ◽  
Experimental Results

This article focus on the calculation of photodecomposition rate constant of PVC films that containing sulfadiazine tin(IV) complexes 1-3 as photostabilzers during UV radiation exposure. This constant calculated as a method for evaluating the efficiency of sulfadiazine tin(IV) complexes 1-3 when used as a PVC photostabilizers after 300 hours of irradiation. The experimental results showed that sulfadiazine tin(IV) complexes 1-3 have reduced the rate of photodecomposition constant value of PVC films significantly with comparison to PVC (blank).

Sub-threshold near-UV radiation effects on aphakic guinea pig retinas

1982 ◽  
Vol 2 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Michael A. Rudy ◽  
Seymour Zigman ◽  
Stephen J. Girsch ◽  
Eric Schenk
Keyword(s):  
Guinea Pig ◽  
Uv Radiation ◽  
Radiation Effects

Gamma and UV radiation effects on breakdown voltage of neon-filled tube

2005 ◽  
Vol 33 (3) ◽  
pp. 1047-1052 ◽  
Author(s):  
M.M. Pejovic ◽  
M.M. Pejovic ◽  
G.S. Ristic
Keyword(s):  
Uv Radiation ◽  
Breakdown Voltage ◽  
Radiation Effects

Investigation on the Probabilistic Distribution of the Stress Range of Net Cage Floater of Fish Cage for Fatigue Life Prediction

2018 ◽  
Author(s):  
Xiao-Dong Bai ◽  
Yun-Peng Zhao ◽  
Guo-Hai Dong ◽  
Chun-Wei Bi
Keyword(s):  
Fatigue Life ◽  
Probability Density ◽  
Limit State ◽  
Frequency Domain Analysis ◽  
Random Wave ◽  
Stress Range ◽  
Fish Farms ◽  
Short Term ◽  
Element Analysis ◽  
Distribution Of Stress

The failure risk of fish cages has increased in the harsher environmental conditions as fish farms have moved into the open sea in recent years. Fatigue failure is an important limit state for the floating system of the fish cage under the long-term action of waves. This study is presented to investigate the applicable probability density function for estimating fatigue life of the high-density polyethylene (HDPE) floating collars. The stress response of the floating collars system in random wave is firstly analyzed based on the finite element analysis combined with a hydrodynamic model. The stress histories of floating collars under each sea state are counted using the rainflow method as a benchmark for fatigue frequency domain analysis. The distribution of stress range was fitted by various probability density functions including Rayleigh, Weibull, Gamma and generalized extreme value (GEV) distributions. Comparisons of the estimated fatigue life using different distributions with rainflow statistic results were performed. Results indicate fatigue estimation based on the GEV and Gamma distributions by removing the negligible low stress range give much more accurate fatigue damage results of the short-term stress range distribution. While Weibull distribution overestimates the fatigue lifetime of the floating collar based on the short-term distribution of stress ranges.

Concrete Fatigue Life Characteristics of the Different Survival Rates in the Lateral Pressure Conditions

2012 ◽  
Vol 600 ◽  
pp. 250-255
Author(s):  
Qiang Cai ◽  
Ji Ming Kong ◽  
Ze Fu Chen
Keyword(s):  
Fatigue Life ◽  
Life Stress ◽  
Failure Modes ◽  
Survival Curve ◽  
Survival Rates ◽  
Life Distribution ◽  
Fatigue Design ◽  
Set Up ◽  
Fatigue Equation ◽  
Two Parameter

Under cyclic loading of concrete structures, fatigue failure is the main failure modes of fatigue, which has become the fatigue design of concrete structure must be considered, then the concrete fatigue studies must clarify the fatigue life of concrete under different survival curve S-N curve. Based on the statistics of the two parameter Weibull distribution theory, obtain the concrete under different survival rates of fatigue life distribution, namely to improve survival, reduce the fatigue life; stress level is reduced, the fatigue life is increased; and has set up more than 50% under different survival rates of concrete fatigue equation.

scholarly journals Prediction of mechanical properties and fatigue life of nano silver paste in chip interconnection

2020 ◽  
Author(s):  
Hui YANG ◽  
Jihui Wu
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Stress And Strain ◽  
Nano Silver ◽  
Finite Element Software ◽  
Flip Chips ◽  
Empirical Correction ◽  
Prediction Of Mechanical Properties

Abstract The simulation of nano-silver solder joints in flip-chips is performed by the finite element software ANSYS, and the stress-strain distribution results of the solder joints are displayed. In this simulation, the solder joints use Anand viscoplastic constitutive model, which can reasonably simulate the stress and strain of solder joints under thermal cycling load. At the same time this model has been embedded in ANSYS software, so it is more convenient to use. The final simulation results show that the areas where the maximum stresses and strains occur at the solder joints are mostly distributed in the contact areas between the solder joints and the copper pillars and at the solder joints. During the entire thermal cycling load process, the area where the maximum change in stress and strain occurs is always at the solder joint, and when the temperature changes, the temperature at the solder joint changes significantly. Based on comprehensive analysis, the relevant empirical correction calculation equation is used to calculate and predict the thermal fatigue life of nano-silver solder joints. The analysis results provide a reference for the application of nano-silver solder in the electronic packaging industry.

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