Purpose

The purpose of this paper is to present the concept of the author’s method of fatigue properties assessment of polymer composite structures, especially structures having nodes of concentrated force introduction (NCFI) using fatigue test data of coupons of similar composites and the ratio of their structural stress rate factors.

Design/methodology/approach

Basing on fatigue properties of pure composite shells coupons subjected to cyclic loads, and basing on the static strength difference between pure composite shells and shells having the structure affected by NCFI – (considered here as not only a manner of load introduction but also a kind of structural discontinuity), a method of relative fatigue properties reduction (RFPR) was developed. In the RFPR evaluation process, the author used the results of experiments on a special type of an NCFI named “a labyrinth non-adhesive node of concentrated force introduction” (LNA-NCFI) applied in certain composite gliders for fitting glider wings with the fuselage and also referred to design directives relating to primary structure of composite gliders, which are presented in the form of lightness factors linking stress with a structural mass.

Findings

The result of RFPR method application matched well with the results of fatigue tests of the LNA-NCFI type of a NCFI. The RFPR method may significantly facilitate the estimation of fatigue life of a structure with a structural discontinuity or an NCFI.

Practical implications

The RFPR method may significantly facilitate the estimation of fatigue life of a structure with a structural discontinuity or an NCFI.

Originality/value

The paper presents a proposal of a novel simplified method for fatigue life estimation of composite structures having a kind of structural discontinuity or an NCFI.

中文翻译：

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复合结构节点的疲劳性能比较评估

目的

本文的目的是提出作者对聚合物复合材料结构进行疲劳性能评估的方法的概念，尤其是使用相似复合材料试片的疲劳测试数据及其结构应力比对具有集中力引入节点（NCFI）的结构进行评估的方法。速率因子。

设计/方法/方法

基于纯复合材料壳体承受循环载荷的疲劳特性，并基于纯复合材料壳体与具有受NCFI影响的结构的壳体之间的静态强度差–（这里不仅考虑了载荷引入方式，还考虑了一种结构不连续性），开发了一种相对疲劳性能降低（RFPR）的方法。在RFPR评估过程中，作者使用了一种特殊类型的NCFI的实验结果，该NCFI称为“迷宫式非粘力集中力导入节点”（LNA-NCFI），适用于某些复合滑翔机，用于将滑翔机机翼安装到机身上并且还涉及与复合滑翔机基本结构有关的设计规范，这些规范以将应力与结构质量相关联的轻量化因子的形式呈现。

发现

RFPR方法应用的结果与NCFI的LNA-NCFI类型的疲劳测试结果非常吻合。RFPR方法可以极大地促进估算具有结构不连续性或NCFI的结构的疲劳寿命。

实际影响

RFPR方法可以极大地促进估算具有结构不连续性或NCFI的结构的疲劳寿命。

创意/价值

本文提出了一种新颖的简化方法，用于估算具有一种结构不连续性或NCFI的复合结构的疲劳寿命。