scholarly journals Mykhailo Dendiuk, Lyubomir Flud, Nazar Semenyshyn Software implementation of the construction of curves short-term strength of wood with biaxial stress state

2020 ◽  
Vol 8 ◽  
pp. 21-26
Author(s):  
Mykhailo Dendiuk ◽  
◽  
Lyubomir Flud ◽  
Nazar Semenyshyn ◽  
◽  
...  
Keyword(s):  
Stress State ◽  
Failure Criteria ◽  
Biaxial Stress ◽  
Term Strength ◽  
Short Term ◽  
Tangential Plane ◽  
Biaxial Stress State ◽  
Short Term Strength ◽  
Cross Platform ◽  
Stress States

This paper is devoted to implementing the algorithm for constructing short-term strength curves of wood with biaxial stress states in the radial-tangential plane of structural symmetry. To implement this algorithm was developed software based on the Qt cross-platform toolkit, which allows to build and analyze short-term strength curves in the cross section of wood. The created program has a possibility to choose one of three failure criteria, a kind of wood, temperature and humidity distribution of lumber. The C++ program code is designed so that you can easily add another type of wood as well as a failure criterion. To display the curves, you can select table or graph mode. Graphs can be fixed on a graphics widget, and new ones can be added to compare to previous ones. Based on the analysis of the constructed curves, the ultimate stress state of the material in partial cases is established. In conclusion about expedient using some criteria to describe the strength characteristics of wood with strong and weak asymmetry of strength limits.

Low Cycle Fatigue Crack Initiation of Rotating Structures Under Biaxial Stress States

2009 ◽  
Author(s):  
Chao Zhang
Keyword(s):  
Stress State ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Biaxial Stress ◽  
Test Results ◽  
Primary Stress ◽  
Biaxial Stress State ◽  
Fatigue Characteristics ◽  
Stress States

Rotating structures can experience biaxial stress states with a wide range of biaxiality ratios on structure surfaces. Low cycle fatigue (LCF) crack initiation in such conditions demonstrates different fatigue characteristics in terms of crack orientation, fatigue life, etc. The biaxial stress states can be categorized into two types: in-phase and out-of-phase under which fatigue characteristics can be significantly different according to rig test results. This paper presents an investigation of LCF crack initiation under in-phase and out-of-phase biaxial stress states based on rig test results of a nickel alloy. The crack orientations are reviewed and discussed at different stress states. Relations of biaxial LCF life debit factor vs biaxiality ratio are derived (the debit factor is defined as a ratio of the LCF life at a biaxial stress state to the LCF life at corresponding uniaxial stress state which has same cyclic and mean stresses as the primary cyclic and mean stressees of the biaxial stress state). The rig test results showed that the crack orientation is usually normal to the primary stress vector under in-phase biaxial stress states but is inclined to the primary stress vector under out-of-phase stress states. As per the derived biaxial LCF life debit factors, the LCF life was found to be slightly reduced with increasing biaxiality ratios under in-phase biaxial stress states but significantly reduced under out-of-phase biaxial stress states compared with corresponding uniaxial primary stress states. The equivalent cyclic stress fatigue criterion is also employed to theoretically model the biaxial LCF life debit factor under in-phase biaxial stress states. The hydrostatic cyclic stress is included in the equivalent cyclic stress in order to take into account the hydrostatic cyclic pressure effects. The equivalent cyclic stress in the criterion can physically reflect the materials’ ductility reduction under in-phase multiaxial stress states.

Об особенностях использования явления акустоупругости при контроле напряженного состояния анизотропного материала технических объектов при отрицательных температурах

2021 ◽  
pp. 23-32
Author(s):  
А.А. Хлыбов ◽  
А.Л. Углов ◽  
Д.А. Рябов
Keyword(s):  
Stress State ◽  
Uniaxial Stress ◽  
Modern Method ◽  
Biaxial Stress ◽  
Transverse Waves ◽  
Acoustic Anisotropy ◽  
Biaxial Stress State ◽  
Calculation Algorithms ◽  
Arctic Conditions ◽  
Stress States

The paper considers the features of using the modern method of acoustoelasticity for monitoring the uniaxial and biaxial stress state of acoustically anisotropic structural materials as part of technical objects operated in Arctic conditions. The features of using the method of acoustoelasticity for materials with different values of acoustoelastic coefficients, acoustic anisotropy and temperature dependence coefficients of acoustic parameters that appear in the calculation algorithms are analyzed. It has been established that the existing approaches to taking into account temperature effects in acoustoelastic calculations in a number of important cases lead to noticeable errors in determining mechanical stresses in the material of critical technical objects. In this case, taking into account the temperature corrections in a number of cases is necessary for both biaxial (planar) and uniaxial stress states. The presence of anisotropy of thermoacoustic coefficients of transverse waves for materials with anisotropy is shown experimentally. Refined calculation formulas are proposed for determining the uniaxial and biaxial stress state of an anisotropic material, taking into account the anisotropy of the thermoacoustic coefficients of transverse waves.

Effects of Training Loads on Short-term Strength Adaptations in Older Adults

2011 ◽  
Vol 43 (Suppl 1) ◽  
pp. 516
Author(s):  
Sandor Dorgo ◽  
Rebecca J. Reed-Jones ◽  
Chantal A. Vella ◽  
Christina Samples ◽  
Chandrasekhar Bulusu
Keyword(s):  
Older Adults ◽  
Term Strength ◽  
Short Term ◽  
Short Term Strength

SUBSTANTIATION OF THE SPECIFIC CRITERION FOR THE CORROSIVE EFFECT OF FORMATION MEDIA ON THE CYCLIC STRENGTH OF STEEL OF DOWNHOLE EQUIPMENT

2020 ◽  
pp. 60-64
Author(s):  
E.S. Yushin
Keyword(s):  
Approximate Calculation ◽  
Oil And Gas ◽  
Endurance Limit ◽  
Cyclic Strength ◽  
Cyclic Loads ◽  
Term Strength ◽  
Short Term ◽  
Specific Criterion ◽  
Corrosive Effect ◽  
Short Term Strength

The article provides the substantiation of the specific coefficient of corrosion influence, considered per unit of the limit of short-term strength of the metal, with the help of which it is possible to simplify the most approximate calculation of the limited endurance limit of steels of oil and gas equipment operating under cyclic loads, as well as perform subsequent resource calculations.

scholarly journals Strength exercise reduces hepatic pyruvate carboxylase and gluconeogenesis in DIO mice

2020 ◽  
Vol 247 (2) ◽  
pp. 127-138
Author(s):  
Rodrigo Martins Pereira ◽  
Kellen Cristina da Cruz Rodrigues ◽  
Marcella Ramos Sant’Ana ◽  
Guilherme Francisco Peruca ◽  
Ana Paula Morelli ◽  
...  
Keyword(s):  
Strength Training ◽  
Pyruvate Carboxylase ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Mrna Levels ◽  
Strength Exercise ◽  
Term Strength ◽  
Short Term ◽  
Hepatic Glucose ◽  
Short Term Strength

Obesity is linked to a reduction in the control of hepatic glucose production, which is the primary mechanism related to fasting hyperglycemia and the development of type 2 diabetes mellitus (T2DM). The main system involved in hepatic gluconeogenesis synthesis is controlled by pyruvate carboxylase (PC), which increases in obesity conditions. Recently, we showed that short-term strength training is an important tool against obesity-induced hyperglycemia. As aerobic exercise can reduce the hepatic PC content of obese animals, we hypothesized that strength exercise can also decrease this gluconeogenic enzyme. Therefore, this study investigated whether the metabolic benefits promoted by short-term strength training are related to changes in hepatic PC content. Swiss mice were divided into three groups: lean control (Ctl), obese sedentary (ObS), and obese short-term strength training (STST). The STST protocol was performed through one session/day for 15 days. The obese exercised animals had reduced hyperglycemia and insulin resistance. These results were related to better control of hepatic glucose production and hepatic insulin sensitivity. Our bioinformatics analysis showed that hepatic PC mRNA levels have positive correlations with glucose levels and adiposity, and negative correlations with locomotor activity and muscle mass. We also found that hepatic mRNA levels are related to lipogenic markers in the liver. Finally, we observed that the obese animals had an increased hepatic PC level; however, STST was efficient in reducing its amount. In conclusion, we provide insights into new biomolecular mechanisms by showing how STST is an efficient tool against obesity-related hyperglycemia and T2DM, even without body weight changes.

scholarly journals Short-term strength training reduces gluconeogenesis and NAFLD in obese mice

2019 ◽  
Vol 241 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Rodrigo Martins Pereira ◽  
Kellen Cristina da Cruz Rodrigues ◽  
Chadi Pellegrini Anaruma ◽  
Marcella Ramos Sant’Ana ◽  
Thaís Dantis Pereira de Campos ◽  
...  
Keyword(s):  
Weight Loss ◽  
Insulin Sensitivity ◽  
Strength Training ◽  
Term Strength ◽  
Obese Mice ◽  
Short Term ◽  
Fat Accumulation ◽  
Hepatic Insulin Sensitivity ◽  
Short Term Strength ◽  
Hepatic Fat

Non-alcoholic fatty liver disease (NAFLD) has a positive correlation with obesity, insulin resistance and type 2 diabetes mellitus (T2D). The aerobic training is an important tool in combating NAFLD. However, no studies have demonstrated the molecular effects of short-term strength training on the accumulation of hepatic fat in obese mice. This study aimed to investigate the effects of short-term strength training on the mechanisms of oxidation and lipid synthesis in the liver of obese mice. The short duration protocol was used to avoid changing the amount of adipose tissue. Swiss mice were separated into three groups: lean control (CTL), sedentary obese (OB) and strength training obese (STO). The obese groups were fed a high-fat diet (HFD) and the STO group performed the strength training protocol 1 session/day for 15 days. The short-term strength training reduced hepatic fat accumulation, increasing hepatic insulin sensitivity and controlling hepatic glucose production. The obese animals increased the mRNA of lipogenic genes Fasn and Scd1 and reduced the oxidative genes Cpt1a and Ppara. On the other hand, the STO group presented the opposite results. Finally, the obese animals presented higher levels of lipogenic proteins (ACC and FAS) and proinflammatory cytokines (TNF-α and IL-1β), but the short-term strength training was efficient in reducing this condition, regardless of body weight loss. In conclusion, there was a reduction of obesity-related hepatic lipogenesis and inflammation after short-term strength training, independent of weight loss, leading to improvements in hepatic insulin sensitivity and glycemic homeostasis in obese mice. Key points: (1) Short-term strength training (STST) reduced fat accumulation and inflammation in the liver; (2) Hepatic insulin sensitivity and HPG control were increased with STST; (3) The content and activity of ACC and content of FAS were reduced with STST; (4) STST improved hepatic fat accumulation and glycemic homeostasis; (5) STST effects were observed independently of body weight change.

Sign in / Sign up

Export Citation Format

Share Document