scholarly journals Constitutive Model of Single Root System’s Resistance to Tensile Stress - Taking Pinus tabulaeformis, Betula platyphylla, Quercus mongolica and Larix gmelinii as Experimental Objects

PLoS ONE ◽  
2014 ◽  
Vol 9 (4) ◽  
pp. e93066 ◽  
Author(s):  
Lihua Chen ◽  
Pinghua Wang ◽  
Yuanjun Yang ◽  
Jia He
Keyword(s):  
Tensile Stress ◽  
Constitutive Model ◽  
Pinus Tabulaeformis ◽  
Larix Gmelinii ◽  
Betula Platyphylla ◽  
Quercus Mongolica ◽  
Single Root

scholarly journals Mean Annual Wood Density Variations of Larix gmelinii (Rupr.), Quercus mongolica Fisch. ex Ledeb., and Pinus tabulaeformis Carr. at Two Different Stem Heights

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 394
Author(s):  
Lars Sprengel ◽  
Zhongqian Cheng ◽  
Sandra-Maria Hipler ◽  
Shuirong Wu ◽  
Heinrich Spiecker
Keyword(s):  
Wood Density ◽  
Tree Species ◽  
Pinus Tabulaeformis ◽  
Larix Gmelinii ◽  
Tree Age ◽  
Climatic Region ◽  
Forest Stands ◽  
Quercus Mongolica ◽  
Cambial Age ◽  
Pinus Tabulaeformis Carr

Forests are a large carbon sink with an additional substitution effect in the merchantable timber compartment of harvested trees, where carbon stored within the same volume of wood varies depending on wood density. Here, we investigated mean annual air-dry wood density variations depending on cambial age, annual radial increment, and two different stem heights of Larix gmelinii (Rupr.), Quercus mongolica Fisch. ex. Ledeb., and Pinus tabulaeformis Carr. from a first climatic region (Mulan Forest) and exclusively of P. tabulaeformis from a second climatic region (Zhongtiaoshan Forest) in the temperate zone of China. We applied linear mixed-effects models with partly transformed variables and estimated marginal means for pairwise comparisons. Results showed that mean wood density was not significantly different between L. gmelinii (0.626 g cm−3) and Q. mongolica (0.596 g cm−3), but significantly different between P. tabulaeformis from the two different climatic regions (0.445 g cm−3 in Mulan Forest and 0.521 g cm−3 in Zhongtiaoshan Forest). Mean annual wood density within trees except for P. tabulaeformis from Mulan Forest was initially increasing until an intermediate cambial age, after which it decreased again to lower values. These findings showed that tree age had to be considered in assessing carbon sequestration in wood. It also could play an important role in decision making for forest management in Mulan Forest and show the benefit of the wood properties and carbon storage potential of the faster growing L. gmelinii compared to Q. mongolica. Furthermore, these findings gave an indication that intermediate old forest stands for some tree species accumulated more carbon per year within their woody biomass than young stands or old growth forests. Our results may have an impact on the planning of rotation lengths and of tree species composition for forest stands in Mulan Forest and Zhongtiaoshan Forest.

scholarly journals Effect of Climatic Factors on Stem Biomass and Carbon Stock of Larix gmelinii and Betula platyphylla in Daxing’anling Mountain of Inner Mongolia, China

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Dilawar Khan ◽  
Muhammad Atif Muneer ◽  
Zaib-Un- Nisa ◽  
Sher Shah ◽  
Muhammad Amir ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Negative Impact ◽  
Climatic Factors ◽  
High Temperature Stress ◽  
Climatic Conditions ◽  
Larix Gmelinii ◽  
Maximum Temperature ◽  
Betula Platyphylla ◽  
Stem Biomass ◽  
Annual Minimum Temperature

Climate change has become a global concern for scientists as it is affecting almost every ecosystem. Larix gmelinii and Betula platyphylla are native and dominant forest species in the Daxing’anling Mountains of Inner Mongolia, playing a major role in carbon sequestration of this region. This study was carried out to assess the effect of climate variables including precipitation and temperature on the biomass of Larix gmelinii and Betula platyphylla forests. For this purpose, we used the climate-sensitive stem biomass allometric model for both species separately to find out accurate stem biomass along with climatic factors from 1950 to 2016. A total of 66 random plots were taken to attain the data from this study area. Larix gmelinii and Betula platyphylla stem biomass have a strong correlation with annual precipitation (R2 = 0.86, R2 = 0.71, R2 = 0.79, and R2 = 0.59) and maximum temperature (R2 = 0.76, R2 = 0.64, R2 = 0.67, and R2 = 0.52). However, annual minimum temperature (R2 = 0.58, R2 = 0.43, R2 = 0.55, and R2 = 0.46) and annual mean temperature (R2 = 0.40, R2 = 0.22, R2 = 0.36, and R2 = 0.19) have a relatively negative impact on tree biomass. Therefore, we suggest that both species have a very strong adaptive nature with climatic variation and hence can survive under drought and high-temperature stress climatic conditions.

Tensile Stress-Strain Curves Modeling of Four Kinds of Solders with Temperature and Rate Dependence

2005 ◽  
Vol 297-300 ◽  
pp. 905-911 ◽  
Author(s):  
Xu Chen ◽  
Li Zhang ◽  
Masao Sakane ◽  
Haruo Nose
Keyword(s):  
Tensile Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Rate Dependence ◽  
Strain Rates ◽  
Stress Strain ◽  
Rate Range

A series of tensile tests at constant strain rate were conducted on tin-lead based solders with different Sn content under wide ranges of temperatures and strain rates. It was shown that the stress-strain relationships had strong temperature- and strain rate- dependence. The parameters of Anand model for four solders were determined. The four solders were 60Sn-40Pb, 40Sn-60Pb, 10Sn-90Pb and 5Sn-95Pb. Anand constitutive model was employed to simulate the stress-strain behaviors of the solders for the temperature range from 313K to 398K and the strain rate range from 0.001%sP -1 P to 2%sP -1 P. The results showed that Anand model can adequately predict the rate- and temperature- related constitutive behaviors at all test temperatures and strain rates.

Anisotropic constitutive model coupled with damage for Sn-rich solder: Application to SnAgCuSb solder under tensile conditions

2021 ◽  
pp. 105678952110451
Author(s):  
Zhao Zhang ◽  
Sheng Liu ◽  
Kun Ma ◽  
Zhiwen Chen ◽  
Zhengfang Qian ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Constitutive Model ◽  
Damage Evolution ◽  
Mechanical Anisotropy ◽  
Uniaxial Tensile ◽  
Stress Strain ◽  
Proposed Model ◽  
Deformation Behaviors ◽  
Simulation Results ◽  
Anisotropic Constitutive Model

With the rapid development of microelectronics and nanoelectronics, Moore law has significantly slowed down and More than Moore based system in packaging (SiP) is expected to be more and more important, at least for next one to two decades. Mechanical behaviors of interconnect materials such as solders are critical for yield in processes and reliability in testing and operation. Based on the framework of crystal plastic theory and continuum damage mechanics, an anisotropic constitutive model coupled with damage was developed to describe the deformation behaviors of Sn-rich solder. In the proposed model, the inelastic shear rate function was presented by hyperbolic sinusoidal form and power law form. For the damage evolution law, the total shear strain was chosen as the damage function variable. The proposed model was implemented into the general finite element software ABAQUS by forward Euler integration procedure. Some simulation examples were performed to verify the proposed model by comparing the simulation results with the experiments at uniaxial tensile conditions with SnAgCuSb solder chosen as the Sn-rich solder. The tensile stress-strain curves of the simulation results agreed well with the experiments at small strain under different temperatures and strain rates. The simulated stress-rupture stages showed reasonable accuracy with the experiments under four representative tensile conditions. Different tensile stress-strain curves of single grains with orientation of (0-0-0)°, (0-45-0)°, and (0-90-0)° were obtained under the same loading conditions, with an inverse relationship between the tensile strength and elongation. This relationship was in accordance with a referable literature. All these results indicate that the proposed model can describe the deformation behaviors of SnAgCuSb solder well under the tensile conditions in consideration of the mechanical anisotropy and the damage evolution.

scholarly journals Biomass Estimation, Nutrient Accumulation, and Stoichiometric Characteristics of Dominant Tree Species in the Semi-Arid Region on the Loess Plateau of China

2020 ◽  
Vol 12 (1) ◽  
pp. 339
Author(s):  
Guanghua Jing ◽  
Tianming Hu ◽  
Jian Liu ◽  
Jimin Cheng ◽  
Wei Li
Keyword(s):  
Loess Plateau ◽  
Tree Species ◽  
Arid Region ◽  
Pinus Tabulaeformis ◽  
Biomass Estimation ◽  
Betula Platyphylla ◽  
The Loess Plateau ◽  
Nutrient Stock ◽  
Semi Arid Region ◽  
Semi Arid

The biomass estimation, nutrient stock, and stoichiometric characteristics are critical for understanding forest productivity and quality. To date, there is not enough comprehensive research on nutrient stock and stoichiometric characteristics of each tissue among different tree species in the semi-arid region on the Loess Plateau. So, six dominant tree species were selected to estimate the forest biomass by allometric equation and to analyze the effects of tissue and species on biomass allocation and nutrient stock by variance analysis in our study. Results showed that forest biomass, nutrient concentration, nutrient stock, and stoichiometric characteristics varied with tissue and species. Betula platyphylla and Pinus tabulaeformis had high total biomass while Populus davidiana had the least total biomass, and the biomass allocation of each tissue generally followed the order of stem > branch > root > foliage. The weighted mean concentrations of carbon (C), nitrogen (N), and phosphorus (P) changed from 432.67 g·kg−1 to 481.43 g·kg−1, from 6.15 to 8.30 g·kg−1, and from 0.43 to 0.74 g·kg−1, respectively. The relatively high nutrient stocks were observed in Pinus tabulaeformis and Betula platyphylla across organs and in stem across species. The C:N and C:P ratios were higher in stem and root than those in branch and foliage for each species, while the effects of tissue on N:P varied with species. Overall, the N:P ranged from 7.92 for stem (Larix principis-rupprechtii) to 22.18 for foliage (Populus davidiana). Therefore, Pinus tabulaeformis and Betula platyphylla can increase effectively nutrient fixation capacity in the semi-arid region on the Loess Plateau. Also, N or P limitation of tree growth in this region varied with species.

IMPLICATIONS OF A CONSTITUTIVE MODEL FOR STRAIN LOCALIZATION

1988 ◽  
Vol 49 (C3) ◽  
pp. C3-489-C3-496
Author(s):  
B. D. COLEMAN ◽  
M. L. HODGDON
Keyword(s):  
Constitutive Model ◽  
Strain Localization
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