No abstract

No abstract

The quality of fibrous reinforcements used in composite materials can be monitored during the weaving process. Fibrous sensors previously developed in our laboratory, based on PEDOT:PSS, have been adapted so as to directly measure the mechanical stress on fabrics under static or dynamic conditions. The objective of our research has been to develop new sensor yarns, with the ability to locally detect mechanical stresses all along the warp or weft yarn. This local detection is undertaken inside the weaving loom in real time during the weaving process. Suitable electronic devices have been designed in order to record in situ measurements delivered by this new fibrous sensor yarn.

No abstract

No abstract

This paper describes a new approach of Nondestructive Evaluation (NDE) using fibrous sensors inserted inside composite reinforcements during their weaving. A flexible piezoresistive fibrous sensor has been developed and optimized for in situ structural deformation sensing in carbon composites. The sensor was inserted, in the weft direction, in three-dimensional warp interlock reinforcement during the weaving process on a special weaving loom. The reinforcement was then impregnated in epoxy resin and was later subjected to quasi-static tensile strain. It was found that the sensor was able to detect deformations in the composite structure until rupture since it was inserted together with reinforcing tows. The morphological and electromechanical properties of the fibrous sensors have been analyzed using scanning electron microscopy, tomography and yarn tensile strength tester. An appropriate data treatment and recording device has also been developed and utilized. The results obtained for carbon composite specimens under standard testing conditions (NF EN ISO 527-4 Plastiques, CEN, 1997) have validated in situ monitoring concept using our textile fibrous sensors.

This paper investigates the influences of woven fabric type, impact locations and number of layers on ballistic impact performances of target panels through trauma dimension and panel surface damage mechanisms for lightweight women ballistic vest design. Three panels with 30, 35 and 40 layers of two-dimensional plain weave and another two panels with 30 and 40 layers of three-dimensional warp interlock fabrics were prepared. The three-dimensional woven fabric was manufactured using automatic Dornier weaving machine, whereas the two-dimensional fabric (with similar p-aramid fibre type (Twaron®)) was received from the Teijin Company. The ballistic tests were carried out according to NIJ Standard-0101.06 Level IIIA. Based on the result, woven fabric construction type, number of layers and target locations were directed an upshot on the trauma measurement values of the tested target panels. For example, 40 layers of two-dimensional plain weave fabric panels show lower trauma measurement values as compared to its counterpart three-dimensional warp interlock fabric panels with similar layer number. Moreover, 40 layers of two-dimensional fabric panels revealed 47% and 39% trauma depth reduction as compared to panels with 30 layers of two-dimensional fabric panel in moulded (target point 1) and non-moulded (target point 6), respectively. Due to higher amount of primary yarn involvement, two-dimensional plain weave fabric panel face higher level of local surface damages but less severe and fibrillated yarns than three-dimensional warp interlock fabrics panels. Moreover, three-dimensional warp interlock fabric panels required higher number of layers compared to two-dimensional plain weave aramid fabrics to halt the projectiles. Similarly, based on the post-mortem analysis of projectile, higher projectile debris deformation was recorded for panels having higher number of layers for both types of fabrics at similar target locations.

The advantages of green composites are including, but not limited to their environmental friendly nature, lightweight, reduction of production energy and costs, recyclability. This work focuses on the mechanical, thermal and dynamic mechanical properties of biocomposites. For that purpose biosourced polymers were used, namely polylactic acid (PLA) and sisal fiber, and biocomposites were extruded and then injection molded with different contents of sisal fibers (5%, 10%, 15%). The results show that the increase of the rate of reinforcement improves the mechanical and dynamic mechanical properties of the biocomposites made. By the increase of the sisal fiber content the degree of crystallinity of the matrix was increased from 47% to 61%, as sisal fibers were acted as a nucleating agent for the PLA.