TY - THES

T1 - Influence of the Textile Architecture on its Transversal Compaction Behaviour

AU - Hollitsch, Markus

N1 - no embargo

PY - 2023

Y1 - 2023

N2 - To characterize the compaction and relaxation behaviour of different textile reinforcement architectures, a specially developed experimental setup is used in which the specimens are compacted between two rigid steel plates by a defined movement of the crosshead of a universal testing machine. Currently established measurement standards do not yet specify the exact test specimen and geometries. Compaction measurements on different material structures and measurement specifications will help to provide a basis for a specification of the methodology. In this thesis, the relaxation behaviour of different textile architectures is investigated in the context of a novel in-situ impregnation measurement methodology and differences are attributed to the material structure. For this purpose, two series of compaction measurements are carried out on a total of four structurally different reinforcing materials while changing various process parameters. In particular, the investigations show the influence of fibre volume fraction as well as the number of layers on the course of stress relaxation in the dry and saturated textile state. Especially during the injection phase of the test fluid, the difference between the material responses of the individual textile architectures is shown by three different preselected pressure levels. During the injection phase of a test liquid, the combination of the already existing compaction pressure and the applied fluid injection pressure results in a defined total pressure. The differences between the compaction pressure levels at the end of the dry and saturated relaxation phases show a significant difference in the strength of the lubrication effect, due to the presence of a fluid, within the investigated textile architectures. A comparison with an International Benchmark Exercise shows that with doubled specimen dimensions, no discernible change in compaction behaviour can be detected. The influence between the pre-impregnation of the specimen with test fluid and in-situ impregnation in a single experiment is also expected to be minor. In addition, influences regarding the measurement results, especially through the handling before testing of the specimens, but also through the test rig itself, have been identified.

AB - To characterize the compaction and relaxation behaviour of different textile reinforcement architectures, a specially developed experimental setup is used in which the specimens are compacted between two rigid steel plates by a defined movement of the crosshead of a universal testing machine. Currently established measurement standards do not yet specify the exact test specimen and geometries. Compaction measurements on different material structures and measurement specifications will help to provide a basis for a specification of the methodology. In this thesis, the relaxation behaviour of different textile architectures is investigated in the context of a novel in-situ impregnation measurement methodology and differences are attributed to the material structure. For this purpose, two series of compaction measurements are carried out on a total of four structurally different reinforcing materials while changing various process parameters. In particular, the investigations show the influence of fibre volume fraction as well as the number of layers on the course of stress relaxation in the dry and saturated textile state. Especially during the injection phase of the test fluid, the difference between the material responses of the individual textile architectures is shown by three different preselected pressure levels. During the injection phase of a test liquid, the combination of the already existing compaction pressure and the applied fluid injection pressure results in a defined total pressure. The differences between the compaction pressure levels at the end of the dry and saturated relaxation phases show a significant difference in the strength of the lubrication effect, due to the presence of a fluid, within the investigated textile architectures. A comparison with an International Benchmark Exercise shows that with doubled specimen dimensions, no discernible change in compaction behaviour can be detected. The influence between the pre-impregnation of the specimen with test fluid and in-situ impregnation in a single experiment is also expected to be minor. In addition, influences regarding the measurement results, especially through the handling before testing of the specimens, but also through the test rig itself, have been identified.

KW - Harzinjektionsverfahren

KW - Textile Verstärkungsarchitekturen

KW - Kompaktierung

KW - In-situ Imprägnierung

KW - Trockene und gesättigte Spannungsrelaxation

KW - Liquid composite molding (LCM)

KW - Reinforcing textile architecture

KW - Compressibility

KW - In-situ impregnation

KW - Dry and wet stress relaxation

U2 - 10.34901/MUL.PUB.2023.16

DO - 10.34901/MUL.PUB.2023.16

M3 - Master's Thesis

ER -