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.

粘合剂层压技术无疑是使加拿大木材产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工程木制产品（EWP）的生产。加拿大木材科学家和工业界已经确定了采用这种强调EWP的技术原因，例如：***（1）可用的软木和硬木原木的直径已大大改善；和***（2）早期进入高价值EWP市场的高潜力，具有诸如用于铁路线路的交叉层压木材和层压木架等产品。 *****必须准确评估和估计粘合层状木材产品的粘结强度和寿命。当前，评估层压产品键强度的最广泛的方法是一种所谓的“块剪切测试”，该测试是在加拿大和美国标准中指定的。但是，研究表明，这种方法是不可靠的，因为粘结强度的失败通常发生在木材中，而不是沿着粘结线，而粘结线未能提供适当的粘合键强度信息。仔细观察了块剪切标本的试样构型和实验设置，表明在标本凹口的剪切和正常应力的复杂组合中存在，并且沿剪切平面的弯曲应力是负载中的弯曲应力。这需要一种新的评估方法。 *****该计划的总体主题是研究层压工程木制产品的界面粘附和断裂行为，从而有助于对其粘结特征的基本了解，以及进一步的实质性贡献，以创造增值木材产品。具体目标是开发一种评估层压木料键质量的正确方法。将招募四名研究生和四名本科生，并将应用机制理论在短跨弯曲下沿层压标本的粘结线进行裂纹分析，并将结果与​​常规块剪切测试方法的结果进行比较。将考虑对称和不对称构型的考虑，这两者都存在于并行和交叉层压木料中。该提议的计划的预期结果是：***（1）通过开发合适的近现实测试方法对层压工程木材产品的键特性的基本了解，以及***（2）（2）（2）一项针对测量加拿大木材标准协会和美国测试和材料的新测试方法的提案。