Comparison of mechanical properties of thermally modified wood at growth ring and cell wall level by means of instrumented indentation tests

Holzforschung ◽  
2009 ◽  
Vol 63 (4) ◽  
Author(s):  
Stefanie Stanzl-Tschegg ◽  
Wilfried Beikircher ◽  
Dieter Loidl
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Thermal Treatment ◽  
Mechanical Performance ◽  
Growth Ring ◽  
Beech Wood ◽  
Thermal Modification ◽  
Wood Structure ◽  
Instrumented Indentation ◽  
Indentation Tests

Abstract Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

Local Mechanical Properties of Cu-Co Alloys with Coherent Co Precipitates

2015 ◽  
Vol 662 ◽  
pp. 15-18
Author(s):  
Jiří Buršík ◽  
Vilma Buršíková ◽  
Milan Svoboda
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Solid Solution ◽  
Thermal Treatment ◽  
Analytical Electron Microscopy ◽  
Water Quenching ◽  
Large Area ◽  
Analytical Electron ◽  
Indentation Tests ◽  
Co Alloys

In this work the influence of the thermal treatment on the local mechanical properties of model diluted Cu-Co alloys with Co content of 4 at.% is investigated. The samples underwent annealing at 1273 K followed by water quenching. The further thermal treatment at 1073 K of the oversaturated solid solution generated a fine distribution of Co-rich precipitates. Parameters of microstructure were evaluated by means of analytical electron microscopy. The nanoscale mechanical properties of precipitates, areas adjacent to the precipitates and precipitate-free zones were studied using large area grid indentation tests. Moreover, the modulus mapping capability was applied to obtain quantitative maps of the storage and loss stiffness and modulus.

scholarly journals Mechanical properties changes in fir wood (abies sp.), linden wood (tilia sp.), and beech wood (fagus sp.) subjected to various thermal modification process conditions

2021 ◽  
Vol 1208 (1) ◽  
pp. 012025
Author(s):  
Redžo Hasanagić ◽  
Sauradipta Ganguly ◽  
Ermin Bajramović ◽  
Adem Hasanagić
Keyword(s):  
Mechanical Properties ◽  
Beech Wood ◽  
Construction Materials ◽  
Treated Wood ◽  
Thermal Modification ◽  
Process Conditions ◽  
Modification Process ◽  
Maximum Duration ◽  
Different Temperatures ◽  
Control Samples

Abstract Wood is one of the most important construction materials in Europe and its use in building applications has increased in the recent decades. To enable even more extensive and reliable use of wood, this article aimed to determine the effect of thermal modification on mechanical properties of fir wood (lat. Abies sp.), linden wood (lat. Tilia sp.), and beech wood (lat. Fagus sp.). The thermal modification was conducted in a laboratory oven at five different temperatures of 170, 180, 195, 210, 220 °C and processed with a different maximum duration of the process of 78, 120, 180, 240, 276 minutes. Mechanical properties of treated wood have shown statistically insignificant fluctuations at lower temperatures compared to control samples. On the other hand, raising the temperature to 210 °C significantly affected the strength of all the species. The results revealed that thermal modification at high temperatures and longer exposure causes a decrease in the maximum force of the three wood species.

scholarly journals Indentation for investigation of strain rate effect on mechanical properties in structural steel weld zone

2019 ◽  
Vol 13 (3) ◽  
pp. 104-112
Author(s):  
Pham Thai Hoan ◽  
Nguyen Ngoc Vinh ◽  
Nguyen Thi Thanh Tung
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Strain Rate ◽  
Structural Steel ◽  
Weld Zone ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Steel Weld ◽  
Instrumented Indentation ◽  
Indentation Tests

In this study, instrumented indentation testing was conducted at room temperature for the investigation of the effect of strain rate on the hardness and yield strength in the weld zone of a commonly used structural steel, SM520. A number of indentation tests were undertaken at a number of strain rate values from 0.02 s-1 to 0.2 s-1 in the weld metal (WM), heat-affected zone (HAZ), and base metal (BM) regions of the weld zone. The mechanical properties including yield strength (σy) and hardness (H) in WM, HAZ, and BM were then computed from the applied load-penetration depth curves using a proposed method. As the result, the effects of strain rate indentation on yield strength and hardness in all regions of the weld zone were evaluated. The results displayed that hardness and yield strength in the weld zone’s components are influenced on the strain rate, where both hardness and yield strength decrease with the decreasing strain rate. Keywords: indentation; mechanical properties; strain rate effect; structural steel; weld zone.

scholarly journals Effect of the Drying Method of Pine and Beech Wood on Fracture Toughness and Shear Yield Stress

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4692
Author(s):  
Daniel Chuchala ◽  
Jakub Sandak ◽  
Kazimierz A. Orlowski ◽  
Tomasz Muzinski ◽  
Marcin Lackowski ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Yield Stress ◽  
Mechanical Performance ◽  
Process Analysis ◽  
Beech Wood ◽  
Drying Methods ◽  
Shear Yield Stress ◽  
Cutting Power ◽  
Shear Yield

The modern wood converting processes consists of several stages and material drying belongs to the most influencing future performances of products. The procedure of drying wood is usually realized between subsequent sawing operations, affecting significantly cutting conditions and general properties of material. An alternative methodology for determination of mechanical properties (fracture toughness and shear yield stress) based on cutting process analysis is presented here. Two wood species (pine and beech) representing soft and hard woods were investigated with respect to four diverse drying methods used in industry. Fracture toughness and shear yield stress were determined directly from the cutting power signal that was recorded while frame sawing. An original procedure for compensation of the wood density variation is proposed to generalize mechanical properties of wood and allow direct comparison between species and drying methods. Noticeable differences of fracture toughness and shear yield stress values were found among all drying techniques and for both species, but only for beech wood the differences were statistically significant. These observations provide a new highlight on the understanding of the effect of thermo-hydro modification of wood on mechanical performance of structures. It can be also highly useful to optimize woodworking machines by properly adjusting cutting power requirements.

Nouvelles techniques d'évaluation et de traitement du hêtre pour des applications durables en construction | New Grading and Treatment Techniques for Beech Used in the Construction Industry

2000 ◽  
Vol 151 (7) ◽  
pp. 253-256 ◽  
Author(s):  
Jean-Luc Sandoz ◽  
Arnaud Pavillet ◽  
Lionel Demay
Keyword(s):  
Mechanical Properties ◽  
Construction Industry ◽  
Chemical Treatment ◽  
Beech Wood ◽  
Added Value ◽  
Wood Structure ◽  
Furniture Industry ◽  
Treatment Techniques ◽  
Ultrasonic Measurements

Swiss forests produce more hardwood – mainly beech – than the local woodworking industry can absorb. Where beech wood is exposed to weather, it cannot be used without a previous chemical treatment due to its naturally bad resistance to decay and insect attacks. The coloured heartwood of beech also restricts its use, especially in the furniture industry. An ultrasonic pre-grading allows to reach a higher added value for beech timber. Sylvatest and Sylvatest Duo, two instruments based on ultrasonic measurements, detect irregularities in the wood structure and allow timber-grading with regard to mechanical properties. Together with thermic treatments,which improve their resistance and durability, these techniques provide new utilisation possibilities for hardwood in the construction industry.

Mechanical Properties of Wear Tested LIGA Nickel

2004 ◽  
Vol 841 ◽  
Author(s):  
N. R. Moody ◽  
J. M. Jungk ◽  
M. S. Kennedy ◽  
S. V. Prasad ◽  
D. F. Bahr ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Work Hardening ◽  
Friction And Wear ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Frictional Contacts ◽  
Indentation Tests ◽  
Work Hardening Coefficient ◽  
Silicon Based ◽  
Hardening Coefficient

ABSTRACTStrength, friction, and wear are dominant factors in the performance and reliability of materials and devices fabricated using nickel based LIGA and silicon based MEMS technologies. However, the effects of frictional contacts and wear on the mechanical performance of microdevices are not well-defined. To address these effects on performance of LIGA nickel, we have begun a program employing nanoscratch and nanoindentation. Nanoscratch techniques were used to generate wear patterns using loads of 100, 200, 500, and 990 μN with each load applied for 1, 2, 5, and 10 passes. Nanoindentation was then used to measure properties in each wear pattern correcting for surface roughness. The results showed a systematic increase in hardness with applied load and number of nanoscratch passes. The results also showed that the work hardening coefficient determined from indentation tests within wear patterns follows the work hardening behavior established from tensile tests, supporting use of a nanomechanics-based approach for studying mechanical properties of wear tested material.

scholarly journals Study of mechanical performance of polymer nanocomposites reinforced with exfoliated graphite of different mesh sizes using micro-indentation

2021 ◽  
pp. 002199832199321
Author(s):  
S Khammassi ◽  
M Tarfaoui ◽  
K Lafdi
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Exfoliated Graphite ◽  
Displacement Curve ◽  
Particle Sizes ◽  
Reinforced Polymers ◽  
Indentation Tests ◽  
Nano Additives ◽  
The Right ◽  
Micro Indentation

The first phase of this work aims to use the right additive nano-fillers choices, such as exfoliated Graphite (ExG), increasing the mechanical, electrical, and thermal performances. In this work, we are interested in quantifying the effect particles' size on a polymer matrix's performance. For this, three sets of exfoliated polymers filled with Graphite, characterized by three particle sizes, called meshes 50, 100, and 150, were investigated. In this analysis, exfoliated Graphite reinforced polymers were subjected to indentation tests to define local mechanical properties. The sample is an epoxy 862 matrix reinforced with exfoliated graphite additives. For each specific size, the additives are mixed in percentages of 0% in the act of control, 0.5%, 4%, 8%, and 16% by weight. Matching pure polymers, polymers reinforced by exfoliated Graphite have proven to have significant improvements in local elastic properties (such as modulus, hardness, stiffness, etc.). Results showed that the reinforced epoxy's local mechanical properties are affected by the size and the percentage of nano-additives. Through the inspection of the load-displacement curve, it can be concluded that the nano-additive has a significant influence on the plastic mechanical properties of the sample. Therefore, the size of nanoparticles has significantly improved in material properties.

scholarly journals THERMAL MODIFICATION OF SUGARCANE WASTE AND BAMBOO PARTICLES FOR THE MANUFACTURE OF PARTICLEBOARDS

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Flávia Maria Silva Brito ◽  
Geraldo Bortoletto Júnior
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Sugarcane Bagasse ◽  
Dimensional Stability ◽  
Industrial Waste ◽  
Urea Formaldehyde ◽  
Dry Mass ◽  
Thermal Modification ◽  
Thickness Variation ◽  
Dendrocalamus Asper

ABSTRACT The thermal modification of particles of the paticleboards constituted of agroforest and industrial waste can improves the dimensional stability (thickness variation) and reduces the use of chemicals that can raise the costs of the process or be hazardous to humans and the environment. This study evaluated the effect of the thermal modification on the physical-mechanical properties and density profile of particleboards manufactured from sugarcane bagasse and bamboo (Dendrocalamus asper) (Schult f.) Backer ex Heyne). A mixture of 75% bamboo particles and 25% sugarcane bagasse was subjected to 220 °C temperature for 201 min. Urea-formaldehyde (UF)-based adhesive with three solids contents (10, 12 and 14%) based on the dry mass of the particles was used for the aggregation of the materials. Both temperature and increases in the adhesive content improved their dimensional stability, however, the thermal treatment reduced the mechanical properties. The particleboards composed of treated particles did not meet the minimum specifications established by the Brazilian norm utilized. The densitometric profiles were negatively influenced by the thermal modification and improved by the increase in adhesive content.

scholarly journals Strain rate effect on semi-crystalline PLLA mechanical properties measured by instrumented indentation tests

2014 ◽  
Vol 59 ◽  
pp. 239-246 ◽  
Author(s):  
S.C. Cifuentes ◽  
E. Frutos ◽  
R. Benavente ◽  
J.L. González-Carrasco ◽  
V. Lorenzo
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Instrumented Indentation ◽  
Indentation Tests
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