在组织尺度上挪威杉的拉伸爬行
Alessia Ferrara1, Falk K Wittel1
1Institute for Building Materials, ETH Zurich, HIF E 28, Laura-Hezner-Weg 7, Zürich, 8093 Switzerland.
概括
树木 树木 树木 树木
科学领域:
- 树木科学和机械学 树木科学和机械
- 材料科学 是一种材料科学.
- 生物力学 生物力学
背景情况:
- 木材的质行为是复杂的,受到规模,方向,湿度和负荷的影响.
- 了解木材的粘性弹性对于结构应用和材料设计至关重要.
研究的目的:
- 研究挪威杉 (Picea abies) 的粘弹性爬行反应.
- 分析湿度和负载程度对不同解剖方向和组织 ( earwood 和 latewood) 的爬行顺应的影响.
- 将爬行和弹性合规性进行比较,以了解依赖湿度的缩放行为.
主要方法:
- 使用定制设计的,自动化测试架,精确控制湿度.
- 在挪威杉组织上进行了单轴爬行测试.
- 检查了所有解剖学方向的爬行合规性,以及在孤立的earwood (EW) 和latewood (LW) 切片中.
主要成果:
- 在木材的爬行反应中表现出显著的方向依赖.
- 突出了水分含量对变形机制的关键影响.
- 观察到细胞壁曲和横向拉伸之间的复杂相互作用,导致对水分敏感的爬行.
结论:
- 木材的爬行行为是高度异质的,对水分含量敏感.
- 横向方向由于曲和细胞壁拉伸而表现出更符合规则和对水分敏感的爬行.
- 对木材组织和方向的详细分析对于了解散装爬行行为至关重要.
更多相关视频
11:38Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization
Published on: August 20, 2013
10.1K
08:58Atomic Force Microscopy Cantilever-Based Nanoindentation: Mechanical Property Measurements at the Nanoscale in Air and Fluid
Published on: December 2, 2022
2.8K
相关概念视频
Factors Affecting Creep
105
In normal-weight aggregate concrete, the hardened cement paste is the primary contributor to creep, whereas the aggregates, being stiffer than the cement paste, are more resilient to stress-induced deformation. The stiffness of the aggregates is defined by their modulus of elasticity, and the more voluminous they are in the concrete, the less it will creep.
Further, the water/cement ratio is critical, as a lower ratio increases concrete strength, thus reducing creep. The strength of the...
Further, the water/cement ratio is critical, as a lower ratio increases concrete strength, thus reducing creep. The strength of the...
105
Strain and Elastic Modulus
3.4K
The quantity that describes the deformation of a body under stress is known as strain. Strain is given as a fractional change in either length, volume, or geometry under tensile, volume (also known as bulk), or shear stress, respectively, and is a dimensionless quantity. The strain experienced by a body under tensile or compressive stress is called tensile or compressive strain, respectively. In contrast, the strain experienced under bulk stress and shear stress is known as volume and shear...
3.4K
Normal Strain under Axial Loading
420
Normal strain under axial loading is an important concept in the field of mechanics of materials. Axial loading implies the application of a force along the axis of a material, like a column or bar. This force can either compress or stretch the material. In the context of axial loading, normal strain is the deformation experienced by the material in the direction of the loading force. It's calculated as the change in length divided by the original length of the material. This unitless ratio...
420
Effects of Creep
81
Creep in concrete, the gradual deformation under prolonged stress, significantly impacts the integrity of structures. For reinforced concrete beams, it can be a vital design consideration, as it increases deflection, sometimes necessitating additional design measures. In columns, especially slender ones under eccentric loads, creep can cause buckling, compromising their stability. However, creep can be beneficial in indeterminate structures by mitigating stresses that arise from shrinkage,...
81
Creep in Concrete
127
Creep refers to the time-dependent increase in strain under a sustained load, excluding other time-dependent deformations associated with shrinkage, swelling, and thermal expansion in concrete. The primary mechanism behind creep involves the loss of physically adsorbed water from the calcium silicate hydrate within the hydrated cement paste. This process is further exacerbated by concrete's non-linear stress-strain relationship, microcrack development in the interfacial transition zone, and...
127
Plastic Behavior
181
A material's elastic behavior is characterized by the disappearance of stress once the load is removed, allowing the material to return to its original state. However, when stress surpasses the yield point, yielding commences, marking the onset of plastic deformation or permanent set. This change from elastic to plastic behavior is influenced by the peak stress value and the duration before the load is removed. An intriguing observation occurs when a specimen is loaded, unloaded, and...
181
