Interfacial adhesion and fracture behaviour of laminated engineered wood products

层压工程木制品的界面粘合和断裂行为

• 批准号: RGPIN-2017-03994
• 负责人: Gong, Meng
• 金额: $ 1.75万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=679810
• 关键词: Interfacial; adhesion; fracture; behaviour; laminated

Adhesive laminating technology is no doubt one of the driving forces keeping Canada's wood products producers more competitive, and it relies on the production of high-performance and durable engineered wood products (EWPs). Canadian wood scientists and industry have identified technical reasons for adopting such an emphasis on EWPs, such as: ***(1) Diameters of available softwood and hardwood logs have been dramatically decreased; and ***(2) High potential exists for early entry to high-value EWP markets with products like cross laminated timber for construction and laminated wood crossties for railway lines. ******The bond strength and life span of adhesive laminated wood products must be accurately evaluated and estimated. Currently, the most widely-adopted method for evaluating the bond strength of a laminated product is a so-called “block shear test,” which is specified in Canadian and American Standards. However, research has revealed that such a method is not reliable since a failure in bond strength usually occurs in the wood, rather than along a bondline, which fails to provide proper adhesive bond strength information. A close look at the specimen configuration and experimental setup of a block shear specimen reveals that there exists a complex combination of shear and normal stresses at the corner of a specimen notch, and that bending stresses along the shear plane are a result of misalignment(s) in loading. This calls for a new evaluation method. ******The overall theme of this proposed program is the study of interfacial adhesion and fracture behaviour of laminated engineered wood products, thereby contributing to a fundamental understanding of their bonding characteristics, as well as a further substantial contribution to creation of value-added wood products. The specific objective is to develop a proper method for the evaluation of bond quality of laminated wood products. Four graduate students and four undergraduate students will be recruited and will apply mechanics theories to conduct crack analysis along the bondlines of laminated specimens under short-span bending and will compare the results with those from conventional block shear test approaches. Considerations will be given to both symmetric and asymmetric configurations, which both exist in parallel and cross laminated wood products. The expected outcomes of this proposed program are:***(1) a fundamental understanding of the bond characteristics of laminated engineered wood products through the development of suitable near-reality test methods, and ***(2) a proposal on new test methods for measuring the bond strength of laminated wood products to the Canadian Standards Association and the American Society for Testing and Materials.

胶粘层压技术无疑是保持加拿大木制品生产商更具竞争力的驱动力之一，它依赖于高性能和耐用的工程木制品（EWP）的生产，加拿大木材科学家和行业已经确定了采用此类技术的技术原因。强调 EWP，例如： ***(1) 可用的软木和硬木原木的直径已大大减小；以及 ***(2) 交叉层压等产品具有早期进入高价值 EWP 市场的巨大潜力；建筑用木材和铁路线的层压木枕木 ****** 必须准确评估和估计胶粘层压木制品的粘合强度和寿命，这是目前最广泛采用的评估粘合强度的方法。层压产品采用加拿大和美国标准中规定的所谓“块剪切测试”。然而，研究表明，这种方法并不可靠，因为粘合强度的失效通常发生在木材中，而不是沿着木材。粘合线，无法提供适当的粘合强度仔细观察块剪切样本的样本配置和实验设置，可以发现样本凹口拐角处存在剪切应力和法向应力的复杂组合，并且沿剪切平面的弯曲应力是未对准的结果。这需要一种新的评估方法，因此该计划的总体主题是研究层压工程木制品的界面粘合和断裂行为，有助于对它们的基本了解。粘合特性，以及其具体目标是开发一种适当的方法来评估层压木制品的粘合质量，并将招募四名研究生和四名本科生，并应用力学理论进行裂纹。沿着短跨度弯曲下的层压样本的粘合线进行分析，并将结果与​​传统的块剪切测试方法的结果进行比较，并将考虑对称和非对称配置，这两种配置都存在于平行和交叉层压木制品中。结果该拟议计划是：***(1) 通过开发合适的接近现实的测试方法，对层压工程木制品的粘合特性有基本的了解，以及 ***(2) 关于测量粘合强度的新测试方法的建议层压木制品的粘合强度符合加拿大标准协会和美国测试与材料协会的规定。