TY - THES

T1 - Evaluation of repairing techniques for damaged natural fiber reinforced composites

AU - Cardenas Velasco, Juan

N1 - no embargo

PY - 2023

Y1 - 2023

N2 - Fiber reinforced polymer composites employed in industries such as aerospace and automotive, are susceptible to deteriorate over time as a result of impact and moisture absorption. With the widespread use of composite materials, the demand for technologies capable of repairing damaged components rather than replace them has increased in past decade. Additionally, the use of bio-based constituents in composites materials shows an upward trend in the industry. This work will focus on repairing natural fiber reinforced composites, specifically Flax-based composites. For this purpose, two formulations of resin are utilized, a bio-based epoxy resin and a Vitrimer resin. Each resin system undergoes a distinct repair technique: injection repair for epoxy-based composites and forming for Vitrimer-based ones. The specimens were produced using vacuum assisted resin infusion. The specimens were cut from these plates. A drop weight impact machine was used to damage the specimens in controlled, low-velocity impact test. The repair process for damaged epoxy-based specimens involves resin injection aided by vacuum. The damaged Vitrimer-based specimens were formed over a four-hour period within a heating press operating at 160°C. The efficiency of the repair methods was assessed using active thermography and compression after impact test. Both evaluation techniques demonstrated that the injection repair technique produced favorable results, demonstrating the effectiveness of the repair method for the chosen system. Although the thermographic outcome from the forming technique were positive, the compression properties highlights is ineffectiveness for the chosen natural fiber and Vitrimeric system.

AB - Fiber reinforced polymer composites employed in industries such as aerospace and automotive, are susceptible to deteriorate over time as a result of impact and moisture absorption. With the widespread use of composite materials, the demand for technologies capable of repairing damaged components rather than replace them has increased in past decade. Additionally, the use of bio-based constituents in composites materials shows an upward trend in the industry. This work will focus on repairing natural fiber reinforced composites, specifically Flax-based composites. For this purpose, two formulations of resin are utilized, a bio-based epoxy resin and a Vitrimer resin. Each resin system undergoes a distinct repair technique: injection repair for epoxy-based composites and forming for Vitrimer-based ones. The specimens were produced using vacuum assisted resin infusion. The specimens were cut from these plates. A drop weight impact machine was used to damage the specimens in controlled, low-velocity impact test. The repair process for damaged epoxy-based specimens involves resin injection aided by vacuum. The damaged Vitrimer-based specimens were formed over a four-hour period within a heating press operating at 160°C. The efficiency of the repair methods was assessed using active thermography and compression after impact test. Both evaluation techniques demonstrated that the injection repair technique produced favorable results, demonstrating the effectiveness of the repair method for the chosen system. Although the thermographic outcome from the forming technique were positive, the compression properties highlights is ineffectiveness for the chosen natural fiber and Vitrimeric system.

KW - Composite repair

KW - Flax

KW - Natural Fiber Composite

KW - Vitrimer

KW - Injection repair

KW - Forming

KW - Drop Weight Impact

KW - Thermography

KW - Compresion After Impact

KW - Verbundwerkstoff-Reparatur

KW - Flachs

KW - Naturfaser-Verbundwerkstoff

KW - Vitrimer

KW - Injektionsreparatur

KW - Umformung

KW - Fallversuch

KW - Thermografie

KW - Compresion After Impact

U2 - 10.34901/mul.pub.2023.203

DO - 10.34901/mul.pub.2023.203

M3 - Master's Thesis

ER -