scholarly journals Woody material structural degradation through decomposition on the forest floor

2018 ◽  
Vol 48 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Shawn Fraver ◽  
Mehdi Tajvidi ◽  
Anthony W. D’Amato ◽  
Daniel L. Lindner ◽  
Jodi A. Forrester ◽  
...  
Keyword(s):  
Mass Loss ◽  
Structural Integrity ◽  
Bending Strength ◽  
Surface Hardness ◽  
Strength Loss ◽  
Carbon Accounting ◽  
Pooled Data ◽  
As Species ◽  
Wood Strength

Dead woody material (DWM) plays numerous important roles in forest ecosystems; however, through the process of decomposition, it undergoes structural and chemical changes that progressively alter its function in these roles. Much remains unknown about how DWM mechanical strength and structural integrity change through decomposition in natural forest settings. We assessed changes in wood strength (bending strength, compressive strength, and surface hardness) using standard wood stakes of known initial mass from three species. The stakes were placed in forested settings for two and four years before collection for laboratory analyses. All three strength metrics decreased as stakes lost mass due to decay; however, bending strength had the strongest relationship with mass loss, a result that was consistent for all species, as well as species-pooled data. Results for all strength-loss metrics indicate that stakes had experienced ca. 10% strength loss before any detectable mass loss had occurred. Further, our results suggest that the decay class system typically used during field inventories — based in large part on tactile assessments of wood structural integrity — may provide a reasonable characterization of DWM mass loss, which is a critical assumption for carbon accounting and modelling based on inventory data.

Characterization and Estimation of Mass Loss Due to Exfoliation Corrosion From Vibration Spectrum

2008 ◽  
Author(s):  
Kumar V. Singh ◽  
Carter Hamilton ◽  
Steven Boehmer
Keyword(s):  
Mass Loss ◽  
Structural Integrity ◽  
Natural Frequencies ◽  
Vibration Spectrum ◽  
Spectral Characteristics ◽  
Beam Specimen ◽  
Spectrum Estimation ◽  
Exfoliation Corrosion ◽  
Non Destructive

Corrosion is a major concern to the aerospace community when evaluating the structural integrity and service-life potential of an airframe. The estimation of corrosion and characterization of material parameters due to such corrosion is of the paramount interest. In this study, corrosion characterization and estimation is considered by using vibration spectrum that can be obtained from non-destructive testing. To that end, aluminum 7075-T6 extrusions were exposed to the exfoliation corrosion environment specified in ASTM G 34 for various times, and the resultant mass loss was measured for each exposure. The corrosion attack was confined to a narrow band centered on the length of a beam specimen by masking the extrusion. Theoretical modeling and lab scale dynamic testing were conducted to establish the correlation between the mass loss and the associated spectral characteristics of the beam (natural frequencies). This research program demonstrates that changes in mass due to exfoliation corrosion may be identified by the measurable change in the spectrum. Estimation/characterization techniques based upon a low dimensional mathematical model as well as based only upon experimental data (natural frequencies) are developed. Successful non-destructive dynamic characterization of aluminum extrusions, therefore, can be the basis of corrosion evaluation and health monitoring of structures operating in corrosive environments.

Flexural Strength and Fatigue Characterization of Exotensioned Composite Beams

2014 ◽  
Vol 30 (3) ◽  
pp. N1-N3 ◽  
Author(s):  
B. J. Rael ◽  
Y.-L. Shen
Keyword(s):  
Structural Integrity ◽  
Mechanical Response ◽  
Bending Strength ◽  
Fiber Composite ◽  
Low Cost ◽  
Carbon Fiber Composite ◽  
High Tension ◽  
Structural Applications ◽  
Load Carrying

ABSTRACTAn exotensioned composite structure is developed as a light-weight and low-cost load carrying members for structural applications. The beam body, consisting of carbon-fiber composite skeletons with insertions of high-tension fiber strands, is externally weaved to provide extra structural integrity. Monotonic and cyclic flexural loading experiments are performed in this study to quantify the basic mechanical response of the structure. The bending strength, ductility, and fatigue resistance are specifically assessed.

Neuropharmacological Characterization of Dioclea altissima Seed Lectin (DAL) in Mice: Evidence of Anxiolytic-like Effect Mediated by Serotonergic, GABAergic Receptors and NO Pathway

2020 ◽  
Vol 26 (31) ◽  
pp. 3895-3904
Author(s):  
João R.C. Araújo ◽  
Adriana R. Campos ◽  
Marina de Barros M.V. Damasceno ◽  
Sacha A.A.R. Santos ◽  
Maria K.A. Ferreira ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Elevated Plus Maze ◽  
Biological Activities ◽  
Plant Lectins ◽  
Plus Maze ◽  
Marble Burying ◽  
Gabaergic Receptors ◽  
The Central Nervous System ◽  
Hole Board

Background: Plant lectins have shown promising biological activities in the central nervous system (CNS). Objective: This study evaluated the effect of DAL, a lectin isolated from the seeds of the Dioclea altissima species, having binding affinity to D-glucose or D-mannose residues, on mice behavior. Methods: Mice (n=6/group) were treated (i.p.) with DAL (0.25, 0.5 or 1 mg/kg) or vehicle and subjected to several tests (open field/OFT, marble-burying/MBT, hole-board/HBT, elevated plus maze/PMT, tail suspension/ TST, forced swimming/FST or rotarod/RRT). Pizotifen, cyproheptadine, flumazenil, L-NAME, 7-NI, Larginine or yohimbine were administered 15 min before DAL (0.5 mg/kg) and the animals were evaluated on PMT. It was also verified whether the DAL effect depended on its structural integrity and ability to interact with carbohydrates. Results: The results showed there were no neurobehavioral changes in the mice at the RRT, FST and locomotion in the OFT. DAL (0.25, 0.5 or 1 mg/kg) increased the behavior of grooming and rearing in the OFT, head dips in the HBT, pedalling in the TST and decreased the number of marbles hidden in the MBT. In the PMT, DAL (0.25, 0.5 and 1 mg/kg) and Diazepam increased the frequency of entries in the open arms and the time of permanence in the open arms without affecting the locomotor activity. The effect of DAL was dependent on carbohydrate interaction and protein structure integrity and it prevented by pizotifen, cyproheptadine, flumazenil, L-NAME and 7-NI, but not by L-arginine or yohimbine. Conclusion: DAL was found to have an anxiolytic-like effect mediated by the 5-HT and GABAergic receptors and NO pathway.

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

scholarly journals The effect of microstructural features on the mechanical properties of LZSA glass-ceramic matrix composites

Cerâmica ◽  
2013 ◽  
Vol 59 (351) ◽  
pp. 351-359 ◽  
Author(s):  
F. M. Bertan ◽  
A. P. Novaes de Oliveira ◽  
O. R. K. Montedo ◽  
D. Hotza ◽  
C. R. Rambo
Keyword(s):  
Glass Ceramic ◽  
Bending Strength ◽  
Chemical Properties ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Linear Shrinkage ◽  
Matrix Composites ◽  
Particulate Reinforced ◽  
And Chemical Properties

This work reports on the characterization of ZrSiO4 particulate-reinforced Li2O-ZrO2-SiO2-Al2O3 (LZSA) glass-ceramic matrix composites. The typical physical/mechanical and chemical properties of the glass batches and the composites were measured. A composition with 60 wt.% ZrSiO4 was preliminarily selected because it demonstrated the highest values of bending strength (190 MPa) and deep abrasion resistance (51 mm³). To this same composition was given a 7 wt.% bentonite addition in order to obtain plasticity behavior suitable for extrusion. The sintered samples (1150 ºC for 10 min) presented a thermal linear shrinkage of 14% and bending strength values of 220 MPa.

A Review of Ultrasonic Application on Non-destructive Testing Method for Concrete Structure

2014 ◽  
Vol 70 (3) ◽  
Author(s):  
Nasarudin Ahmad ◽  
Ruzairi Abdul Rahim ◽  
Herlina Abdul Rahim ◽  
Mohd Hafiz Fazlul Rahiman
Keyword(s):  
Concrete Structure ◽  
High Speed ◽  
Structural Integrity ◽  
Surface Hardness ◽  
Concrete Surface ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Surface Absorption ◽  
Processing Techniques ◽  
Non Destructive

Although the technique of using ultrasound has reached maturity by given the extent of the development of sensors, but the use of the various areas still can be explore. Many types of ultrasonic sensors are still at conventional in use especially for measurement equipment in the industry. With the advancement of signal processing techniques, high-speed computing, and the latest techniques in image formation based Non-destructive testing (NDT) methods, the usage of ultrasound in concrete NDT testing is very extensive because the technique is very simple and should not damage the concrete structure to be investigated. Many of the parameters need to be tested using ultrasound techniques to concrete can be realized. Starting with the initial process for of concrete mixing until the concrete matured to the age of century old. Various tests are available to test a variety of non-destructive of concrete completely, in which there is no damage to the concrete, through those where the concrete surface is damaged a bit, to partially destructive testing, such as core tests and insertion and pull-off test, which surface to be repaired after the test. Testing parameter features that can be evaluated using non-destructive testing and destructive testing of some rather large and include basic parameters such as density, elastic modulus and strength and surface hardness and surface absorption, and reinforcement location, size and distance from the surface. In some cases it is also possible to check the quality of the workmanship and structural integrity of the ability to detect voids, cracks and delamination. A review of NDT using ultrasound on concrete are presented in this paper to highlight the important aspect to consider when one to consider the application and development of ultrasound testing on concrete by considering ultrasound signal capturing, processing and presenting.

Structure Characterization of Sintered CaO-Al2O3-SiO2 Glass-Ceramic Reinforced with Spodumene

2013 ◽  
Vol 834-836 ◽  
pp. 309-314
Author(s):  
Zi Fan Xiao ◽  
Jin Shu Cheng ◽  
Jun Xie
Keyword(s):  
Glass Ceramic ◽  
Energy Dispersive Spectrometry ◽  
Crystal Size ◽  
Bending Strength ◽  
Glass Ceramics ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray

A glass-ceramic belonging to the CaO-Al2O3-SiO2(CAS) system with different composition of spodumene and doping the Li2O with amount between 0~2.5 % (mass fraction) were prepared by onestage heat treatment, under sintering and crystallization temperature at 1120 °C for two hours. In this paper, differential thermal analysis, X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and bending strength test were employed to investigate the microstructure and properties of all samples. β-wollastonite crystals were identified as the major crystalline phases, and increasing Li2O was found to be benefit for the crystallization and tiny crystalline phases remelting, resulting in the content of major crystalline phases increased first and then decreased with increasing the expense of spodumene. Meanwhile, the crystal size can be positively related with the content of Li2O. The preferable admixed dosage of spodumene can be obtained, besides the strength of glass-ceramics can be more than 90 MPa.

Mechanical and Interfacial Characterization of Jute Fabrics Reinforced Unsaturated Polyester Resin Composites

2019 ◽  
Vol 25 ◽  
pp. 22-31 ◽  
Author(s):  
Farhana Islam ◽  
M. Naimul Islam ◽  
Shahirin Shahida ◽  
Harun Ar Rashid ◽  
Nanda Karmaker ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Bending Strength ◽  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Tensile Modulus ◽  
Unsaturated Polyester Resin ◽  
Bending Modulus ◽  
The Matrix ◽  
Jute Fabrics

Jute fabrics reinforced Unsaturated Polyester Resin (UPR)-based composites were prepared by conventional hand lay-up technique. Different proportions (5 to 50% by weight) of fibre content was used in preparation of the composite. Tensile Strength (TS), Tensile Modulus (TM), Bending Modulus (BM), Bending Strength (BS), Impact Strength (IS) of the fabricated composites were studied. Upon each addition of fiber content in the matrix, mechanical properties of the composites were increased. The Tensile Strength (TS) of the 5% and 50% fiber reinforced composites was 18 MPa and 42 MPa respectively. Scanning Electron Microscopy (SEM) showed interfacial properties of the composites and it was revealed that the bond between fiber and matrix was excellent.

Bending Strength of Carburized Forged Spur Gear

2007 ◽  
Author(s):  
Masashi Yamanaka ◽  
Shinji Miwa ◽  
Katsumi Inoue ◽  
Yoshiki Kawasaki
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Bending Strength ◽  
Surface Hardness ◽  
Spur Gear ◽  
Bending Fatigue ◽  
Precision Forging ◽  
Bending Fatigue Test ◽  
Bending Fatigue Strength ◽  
Gear Profile

This paper deals with the evaluation of influence of the manufacturing methods precision forging and conventional hobbing on the bending fatigue strength of carburized gears. The forging has advantages in productivity and strength. The forged gear has a continuous directed fiber flow which runs along the gear profile. To clarify the effect of strength enhancement, a bending fatigue test is performed for the forged and the hobbed gears. The material of test gears is SCr420H in the JIS and all gears are carburized. The electrohydraulic servo-controlled fatigue tester is used in the constant stress-amplitude fatigue test. The strength is expressed by the fillet stress level, which is calculated by FEM. The obtained strengths of forged and hobbed gear are 1613 MPa and 1490 MPa, respectively. The strength of forged gear is increased 8% in comparison with that of the hobbed gear. The surface hardness is higher and the surface roughness is smaller in the forged gear, however, the residual stress is approximately same. The effect of improvement of the roughness by forging on the strength is small in 1%, and the main reason of the improvement of fatigue strength is considered as the continuous fiber flow.

scholarly journals Protocols for the preparation and characterization of decellularized tissue and organ scaffolds for tissue engineering

BioTechniques ◽  
2020 ◽  
Author(s):  
Dar-Jen Hsieh ◽  
Periasamy Srinivasan ◽  
Ko-Chung Yen ◽  
Yi-Chun Yeh ◽  
Yun-Ju Chen ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Structural Integrity ◽  
Human Mesenchymal Stem Cells ◽  
Common Source ◽  
Dermal Matrix ◽  
Wound Model ◽  
3D Architecture ◽  
Severe Shortage ◽  
Full Thickness Wound

Extracellular matrix (ECM) scaffolds are extensively used in tissue engineering studies and numerous clinical applications for tissue and organ reconstructions. Due to the global severe shortage of human tissues and organs, xenogeneic biomaterials are a common source for human tissue engineering and regenerative medicine applications. Traditional methods for decellularization often disrupt the 3D architecture and damage the structural integrity of the ECM scaffold. To efficiently obtain natural ECM scaffolds from animal tissues and organs with intact architecture, we have developed a platform decellularization process using supercritical CO2 and tested its potential application in tissue engineering. A combination of human mesenchymal stem cells with a decellularized dermal matrix scaffold allowed complete regeneration of skin structure in a porcine full-thickness wound model.

Sign in / Sign up

Export Citation Format

Share Document