Characterization and Failure Analysis of Plastics

Volume 11B serves as a reference and guide to help engineers determine the causes of failure in plastic components and make corrective adjustments through design and manufacturing modifications. It contains seven major divisions, covering polymer science and processing, material selection and design, chemical, thermal, and physical analysis, mechanical behavior and testing, degradation mechanisms, systematic failure analysis, and life assessment and optimization. It examines a wide range of factors that contribute to the properties and behaviors of engineering plastics and the effect of thermal and mechanical stresses, impact loading, fatigue, wear, weathering, moisture and chemical exposure, photochemical aging, microbial degradation, and elevated temperatures. It addresses issues such as flammability, environmental stress cracking, crazing, and stress whitening and describes the unique characteristics of polymer fracture and how to assess and predict service life using fracture mechanics. It also presents and analyzes numerous examples of failure, including design and manufacturing related failures, wear failures of reinforced plastics, and failures due to creep and yielding.

Deformation properties of arched glass fiber reinforced plastics structure under static load: Considering the soil cover and rise-span ratio

In this study, the load level, soil cover height, rise-span ratio, and arch foot constraint state were utilized to explore the mechanical properties of buried arch glass fiber reinforced plastics (GFRP) structures. Through the indoor scale-down test, the stress and deformation of arched GFRP structures under different load and soil cover height were investigated. Additionally, through the three-dimensional finite element method, the influence of the rise-span ratio and the constraint state of arch foot on the mechanical properties were obtained. The results indicate the new buried composite arch structure has excellent bearing capacity for the possible traffic load. Simultaneously, the semi-elliptical arch structure was believed to outperform the semi-circular arch structure when considering the external load. Specifically, increasing the soil cover height and reducing rise-span ratio were found to achieve the load-reduction effect.

Experimental study on axial compression buckling of glass fiber reinforced plastics solid pole with circular cross-section

Glass fiber reinforced plastics are widely used in civil engineering because of their advantages such as light weight, high strength, good pollution resistance, and corrosion resistance. This study investigated the buckling bearing capacity, failure characteristics, and slenderness ratios of GFRP solid bars with circular cross-sections subjected to axial compression. A total of 18 specimens were categorized into six groups. The slenderness ratios ranged from 57 to 123. It was found from experiments that the instability mode of the specimens was extreme point instability, and a bearing capacity platform phenomenon was observed when overall lateral instability occurred. The failure mode was axial and transverse tearing failure of the material in the middle of the specimen. During buckling, the tensile side was transformed from the compression of the resin matrix to tension in the fibers. The elastic modulus of glass fiber was much lower than that of the resin matrix. After tension occurred, increased deformation led to a rapid increase in lateral bending, which resulted in the phenomenon of the bearing platform. At ultimate deformation, brittle failure of the specimen occurred. The buckling load of the specimen decreased sharply with an increase in the slenderness ratio, and stress ratios decreased from 34.95% to 6.73%. It is suggested that the slenderness ratio not exceed 80. Finally, based on experimental results, a practical method for calculating the stable bearing capacity of solid GFRP poles is proposed.

A Study on Tensile Behavior According to the Design Method for the CFRP/GFRP Grid for Reinforced Concrete

In the present study, fiber-reinforced plastics (FRP) grid-reinforced concrete with very rapid hardening polymer (VRHP) mortar composites were fabricated using three types of design methods for the FRP grid (hand lay-up method, resin infusion method, and prepreg oven vacuum bagging method), along with two types of fibers (carbon fiber and glass fiber) and two types of sheets (fabric and prepreg). The FRP grid was prepared by cutting the FRP laminates into a 10 mm thick, 50 mm × 50 mm grid. The tensile behavior of the FRP grid embedded in composites was systematically analyzed in terms of the load extension, fracture mode, partial tensile strain, and load-bearing rate. The CFRP grid manufactured by the prepreg OVB method showed the best tensile behavior compared to the CFRP grid manufactured by the hand lay-up and resin infusion methods. The load-bearing of each grid point was proportional to the height from the load-bearing part when reaching the maximum tensile load. In addition, finite element analysis was conducted to compare the experimental and analysis results.

Tensile Properties of 3D-printed Continuous-Fiber-Reinforced Plastics

Obtaining parts made of composite materials through 3D Printing Additive manufacturing have fully proved their usefulness due to a number of advantages such as: the possibility to directly create complex shapes without going through the classic process of transforming the semi-finished products into finished parts through technologies which consume resources and energy and are totally unfriendly to the environment. The main disadvantage of the parts made by 3D Printing technologies is that they are less resistant from a mechanical point of view. This was solved with the emergence of the 3D printers capable of printing composite parts consisting of a plastic matrix reinforced with continuous fibers. This research focuses on studying 4 types of composite materials from the point of view of their mechanical properties: Onyx - a rigid nylon in which micro carbon fibers are inserted and Onyx reinforced with carbon, fiber glass or kevlar. Standardized specimens were made for the uniaxial tensile test and the experimental program was designed evaluating: the Elastic modulus [GPa], the Maximum Tensile stress [MPa], the Tensile strain at maximum Tensile stress [mm/mm]. The principal strains were also determined, by means of the digital image technique made using the Aramis system from GOM. The experimental tests confirm that these new materials will be serious candidates to be used in the engineering applications in various fields.

Processing, Properties, and Uses of Lightweight Glass Fiber/Aluminum Hybrid Structures

The replacement of heavy metallic structures by high-performance lightweight composite materials is a prominent solution to fulfill the continuous demand in different industrial sectors. Lightweight structures based on aluminum-glass fiber reinforced plastics (GFRP) sandwich panels have been increasingly utilized in the shipbuilding, automotive, and aerospace industries for their striking mechanical and physical properties. These advantageous properties have resulted from the combination of the high tensile and flexural strengths, increased hardness, and the improved wear-resistance of aluminum laminate with the unique properties of lightweight stiffness and high strength weight ratio of glass fiber-reinforced. In this chapter, the various processing approaches, properties, and applications of these sandwich structures are summarized from a wide range of literature.