Morphology and Anatomy of Branch–Branch Junctions in Opuntia ficus-indica and Cylindropuntia bigelovii: A Comparative Study Supported by Mechanical Tissue Quantification

The Opuntioideae include iconic cacti whose lateral branch–branch junctions are intriguing objects from a mechanical viewpoint. We have compared Opuntia ficus-indica, which has stable branch connections, with Cylindropuntia bigelovii, whose side branches abscise under slight mechanical stress. To determine the underlying structures and mechanical characteristics of these stable versus shedding cacti junctions, we conducted magnetic resonance imaging, morphometric and anatomical analyses of the branches and tensile tests of individual tissues. The comparison revealed differences in geometry, shape and material properties as follows: (i) a more pronounced tapering of the cross-sectional area towards the junctions supports the abscission of young branches of C. bigelovii. (ii) Older branches of O. ficus-indica form, initially around the branch–branch junctions, collar-shaped periderm tissue. This secondary coverage mechanically stiffens the dermal tissue, giving a threefold increase in strength and a tenfold increase in the elastic modulus compared with the epidermis. (iii) An approximately 200-fold higher elastic modulus of the vascular bundles of O. ficus-indica is a prerequisite for the stable junction of its young branches. Our results provide, for both biological and engineered materials systems, important insights into the geometric characteristics and mechanical properties of branching joints that are either stable or easily detachable.

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Mimicking the Mechanical Properties of Aortic Tissue with Pattern-Embedded 3D Printing for a Realistic Phantom

Materials ◽

10.3390/ma13215042 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5042

Author(s):

Jaeyoung Kwon ◽

Junhyeok Ock ◽

Namkug Kim

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

3D Printing ◽

Mechanical Characteristics ◽

Aortic Wall ◽

Tensile Tests ◽

Human Aorta ◽

Aortic Tissue ◽

Medical Field ◽

Base Materials

3D printing technology has been extensively applied in the medical field, but the ability to replicate tissues that experience significant loads and undergo substantial deformation, such as the aorta, remains elusive. Therefore, this study proposed a method to imitate the mechanical characteristics of the aortic wall by 3D printing embedded patterns and combining two materials with different physical properties. First, we determined the mechanical properties of the selected base materials (Agilus and Dragonskin 30) and pattern materials (VeroCyan and TPU 95A) and performed tensile testing. Three patterns were designed and embedded in printed Agilus–VeroCyan and Dragonskin 30–TPU 95A specimens. Tensile tests were then performed on the printed specimens, and the stress-strain curves were evaluated. The samples with one of the two tested orthotropic patterns exceeded the tensile strength and strain properties of a human aorta. Specifically, a tensile strength of 2.15 ± 0.15 MPa and strain at breaking of 3.18 ± 0.05 mm/mm were measured in the study; the human aorta is considered to have tensile strength and strain at breaking of 2.0–3.0 MPa and 2.0–2.3 mm/mm, respectively. These findings indicate the potential for developing more representative aortic phantoms based on the approach in this study.

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Petiole-Lamina Transition Zone: A Functionally Crucial but Often Overlooked Leaf Trait

Plants ◽

10.3390/plants10040774 ◽

2021 ◽

Vol 10 (4) ◽

pp. 774

Author(s):

Max Langer ◽

Thomas Speck ◽

Olga Speck

Keyword(s):

Transition Zone ◽

Three Dimensional ◽

Spatial Arrangement ◽

Body Plan ◽

The Body ◽

Vascular Bundles ◽

Cross Sectional ◽

Thin Sections ◽

Transition Zones ◽

The Cross

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.

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A Flow Stress Model of 300M Steel for Isothermal Tension

Materials ◽

10.3390/ma14020252 ◽

2021 ◽

Vol 14 (2) ◽

pp. 252

Author(s):

Rongchuang Chen ◽

Shiyang Zhang ◽

Xianlong Liu ◽

Fei Feng

Keyword(s):

Flow Stress ◽

Constitutive Model ◽

Tensile Deformation ◽

Flow Behavior ◽

Tensile Tests ◽

Uniaxial Tensile ◽

Model Parameters ◽

Average Deviation ◽

Cross Sectional ◽

300M Steel

To investigate the effect of hot working parameters on the flow behavior of 300M steel under tension, hot uniaxial tensile tests were implemented under different temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C) and strain rates (0.01 s−1, 0.1 s−1, 1 s−1, 10 s−1). Compared with uniaxial compression, the tensile flow stress was 29.1% higher because dynamic recrystallization softening was less sufficient in the tensile stress state. The ultimate elongation of 300M steel increased with the decrease of temperature and the increase of strain rate. To eliminate the influence of sample necking on stress-strain relationship, both the stress and the strain were calibrated using the cross-sectional area of the neck zone. A constitutive model for tensile deformation was established based on the modified Arrhenius model, in which the model parameters (n, α, Q, ln(A)) were described as a function of strain. The average deviation was 6.81 MPa (6.23%), showing good accuracy of the constitutive model.

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Experimental Investigation into Corrosion Effect on Mechanical Properties of High Strength Steel Bars under Dynamic Loadings

International Journal of Corrosion ◽

10.1155/2018/7169681 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Hui Chen ◽

Jinjin Zhang ◽

Jin Yang ◽

Feilong Ye

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

Dynamic Loading ◽

High Strength Steel ◽

High Strength ◽

Tensile Tests ◽

Reinforcing Steel ◽

Test Results ◽

Cross Sectional ◽

Steel Bars

The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.

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Fabrication and Mechanical Properties of Dense/Porous β-Tricalcium Phosphate Bioceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.330-332.907 ◽

2007 ◽

Vol 330-332 ◽

pp. 907-910

Author(s):

Fa Ming Zhang ◽

Jiang Chang ◽

Jian Xi Lu ◽

Kai Li Lin

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Elastic Modulus ◽

Exponential Growth ◽

Weight Bearing ◽

Area Ratio ◽

Sectional Area ◽

Cross Sectional ◽

The Matrix ◽

Porous Bioceramics

Attempt to increase the mechanical properties of porous bioceramics, a dense/porous structured β-TCP bioceramics that mimic the characteristics of nature bone were fabricated. Experimental results show that the dense/porous structured β-TCP bioceramics demonstrated excellent mechanical properties with compressive strength up to 74 MPa and elastic modulus up to 960 MPa, which could be tailored by the dense/porous cross-sectional area ratio obeying the rule of exponential growth. The interface between the dense and porous bioceramics is connected compactly and tightly with some micropores distributed in the matrix of both porous and dense counterparts. The dense/porous structure of β-TCP bioceramics may provide an effective way to increase the mechanical properties of porous bioceramics for bone regeneration at weight bearing sites.

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Structure optimization of woven fabric composites for improvement of mechanical properties using a micromechanics model of woven fabric composites and a genetic algorithm

Composites and Advanced Materials ◽

10.1177/26349833211006114 ◽

2021 ◽

Vol 30 ◽

pp. 263498332110061

Author(s):

Gunyong Hwang ◽

Dong Hyun Kim ◽

Myungsoo Kim

Keyword(s):

Mechanical Properties ◽

Genetic Algorithm ◽

Elastic Modulus ◽

Fiber Composite ◽

Woven Fabric ◽

Cross Sectional ◽

Micromechanics Model ◽

Woven Fabric Composites ◽

Fabric Composites ◽

Out Of Plane

This research aims to optimize the mechanical properties of woven fabric composites, especially the elastic modulus. A micromechanics model of woven fabric composites was used to obtain the mechanical properties of the fiber composite, and a genetic algorithm (GA) was employed for the optimization tool. The structure of the fabric fiber was expressed using the width, thickness, and wave pattern of the fiber strands in the woven fabric composites. In the GA, the chromosome string consisted of the thickness and width of the fill and warp strands, and the objective function was determined to maximize the elastic modulus of the composite. Numerical analysis showed that the longitudinal mechanical properties of the strands contributed significantly to the overall elastic modulus of the composites because the longitudinal property was notably larger than the transverse property. Therefore, to improve the in-plane elastic modulus, the resulting geometry of the composites possessed large volumes of related strands with large cross-sectional areas and small strand waviness. However, the numerical results of the out-of-plane elastic modulus generated large strand waviness, which contributed to the fiber alignment in the out-of-plane direction. The findings of this research are expected to be an excellent resource for the structural design of woven fabric composites.

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Abstract 3077: Cross-Sectional Associations of Arterial Stiffness Measures and Ankle-Brachial Index: The Multi-Ethnic Study of Atherosclerosis (MESA)

Circulation ◽

10.1161/circ.118.suppl_18.s_810-b ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

John T Wilkins ◽

Mary M McDermott ◽

Kiang Liu ◽

Cheeling Chan ◽

Michael Criqui ◽

...

Keyword(s):

Arterial Stiffness ◽

Mechanical Characteristics ◽

Pulse Wave ◽

Ankle Brachial Index ◽

Arterial Disease ◽

Cross Sectional ◽

Men And Women ◽

Independent Variables ◽

Vascular Impedance ◽

Peripheral Arterial

The association between tonometry-derived measures of arterial stiffness and peripheral arterial disease (PAD) is unclear. Using baseline data from 2847 female and 2614 male participants of the NHLBI-funded MESA study, we conducted linear regression analyses adjusted for age, demographics and risk factors. Ankle-brachial index (ABI) was the dependent variable and measures of large (C1) and small artery elasticity (C2) and total vascular impedance (TVI), all measured from radial artery tonometry, were the independent variables in separate models. In men and women, lower C1 and C2 values were associated with lower ABI. Higher TVI was associated with lower ABI in men and women [P<0.001]. Significant trends for C1, C2 and TVI were observed across clinical strata of ABI (Table ). In pairwise analyses, compared with participants with a normal ABI (1.1 to <1.3), those with ABI <1.1 tended to have significantly lower C2. Additionally, women with high ABI (1.3–1.5) tended to have significantly higher C2 values. Pairwise comparisons of lower and higher ABI groups compared with normal groups did not yield consistent findings for C1. Significantly higher TVI levels with lower ABI group were noted mostly in women (Table ). We observed a continuum of arterial mechanical characteristics across clinical ABI values, indicating that measures of arterial stiffness are significantly associated with ABI and severity of PAD. These results suggest that changes in C2 occur in patients with advanced lower extremity large-vessel atherosclerotic disease. Of note, female participants with high ABI between 1.3–1.5 had a significantly higher C2, arguing against the accepted “non-compressible” or “calcified arterial disease” explanation for high ABI in women. Associations Between ABI and Pulse Wave Analysis Measurements when adjusted for age, cigarette smoking, diabetes, hypertension, and creatinine level

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Mechanical and thermal behaviors of ultra-high molecular weight polyethylene triaxial braids: the influence of structural parameters

Textile Research Journal ◽

10.1177/0040517518811944 ◽

2018 ◽

Vol 89 (16) ◽

pp. 3362-3373 ◽

Cited By ~ 2

Author(s):

Shenglei Xiao ◽

Charles Lanceron ◽

Peng Wang ◽

Damien Soulat ◽

Hang Gao

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Mechanical Characteristics ◽

Structural Parameters ◽

Tensile Tests ◽

Tensile Behavior ◽

Experimental Database ◽

Strength And Deformation ◽

Braiding Angle ◽

Ultra High Molecular Weight

Recently, triaxial braids made from ultra-high molecular weight polyethylene (UHMWPE) have been recognized as one of the most popular composite reinforcements in the aerospace and defense fields. To further explore the mechanical characteristics of this material, a detailed experimental study on tensile behavior is reported in this paper. The triaxial braids show a “double-peak” phenomenon in tensile strength and deformation, caused by axial yarns and the in-plane shearing of bias yarns. The evolution of the braiding angle, measured during these tensile tests, is discussed according to the braiding parameters (initial braiding angle, number of axial yarns). Using the high conductivity properties of the UHMWPE material, the temperature caused by inter-yarn friction during tensile tests is also studied. This temperature is related to the evolution of the braiding angle. The temperature increases with the increasing number of axial yarns and decreases with increasing braiding angle. This study provides an experimental database on the influence of braiding parameters on the tensile behavior of triaxial braids.

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Study on the Mechanical Properties of Chlorine Saline Soil under the Interaction of Multiple Factors

Mathematical Problems in Engineering ◽

10.1155/2021/6669697 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Anhua Xu ◽

Pengcheng Wang ◽

Jianhong Fang

Keyword(s):

Elastic Modulus ◽

Moisture Content ◽

Mechanical Characteristics ◽

External Environment ◽

Confining Pressure ◽

Dynamic Elastic Modulus ◽

Dynamic Strain ◽

Saline Soils ◽

Loading Frequency ◽

Failure Strength

The distribution of chlorine saline soils is extensive in Haixi region of Qinghai Province in Northwest China. Its natural and geographical conditions are unique, and the external environment varies greatly. To study the effects of variable external environment on the mechanical characteristics of chlorine saline soils, a number of unconsolidated undrained (UU) dynamic triaxial tests under different confining pressure, moisture content, and loading frequency were carried out. The dynamic stress–dynamic strain, failure strength, dynamic elastic modulus, and parameter of shear strength were analyzed. The triaxial test results demonstrated that the stress–strain curves of the soil were strain-hardening. The failure strength and dynamic elastic modulus increased with the increasing of confining pressure; the law with moisture content and loading frequency were inconsistent. The dynamic cohesion and dynamic friction angle increased with the increasing of loading frequency, but decreased with the increasing of moisture content. Besides, the significance analysis theory was used to analyze the effect degree of different factors. It found that the effects of confining pressure, loading frequency, and the interaction between confining pressure and frequency on mechanical characteristics were significant, but the moisture content had less effect.

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