Low-Cycle Fatigue Behavior of 3D-Printed PLA Reinforced with Natural Filler

Abstract

Additive production is currently perceived as an advanced technology, where intensive research is carried out in two basic directions—modifications of existing printing materials and the evaluation of mechanical properties depending on individual production parameters and the technology used. The current research is focused on the evaluation of the fatigue behavior of 3D-printed test specimens made of pure PLA and PLA reinforced with filler based on pinewood, bamboo, and cork using FDM (fused deposition modeling) technology. This research was carried out in response to the growing demand for filaments from biodegradable materials. This article describes the results of tensile fatigue tests and image analysis of the fracture surface determined by the SEM method. Biodegradable PLA-based materials have their limitations that influence their applicability in practice. One of these limitations is fatigue life, which is the cyclic load interval exceeding 50% of the tensile strength determined in a static test. Comparison of the cyclic fatigue test results for pure PLA and PLA reinforced with natural reinforcement, e.g., pinewood, bamboo, and cork, showed that, under the same loading conditions, the fatigue life of the 3D-printed specimens was similar, i.e., the filler did not reduce the material’s ability to respond to low-cycle fatigue. Cyclic testing did not have a significant effect on the change in tensile strength and associated durability during this loading interval for PLA-based materials reinforced with biological filler. Under cyclic loading, the visco-elastic behavior of the tested materials was found to increase with increasing values of cyclic loading of 30%, 50% and 70%, and the permanent deformation of the tested materials, i.e., viscoelastic behavior (creep), also increased. SEM analysis showed the presence of porosity, interlayer disturbances, and at the same time good interfacial compatibility of PLA with the biological filler.

3D-Printed Fiber-Reinforced Polymer Composites by Fused Deposition Modelling (FDM): Fiber Length and Fiber Implementation Techniques

“…[ 153 , 154 ]. Previously, most research focused on synthetic fiber reinforced PLA, and currently, some works on natural fiber reinforced PLA are reported [ 103 , 152 ]. The potential of FDM printed fiber reinforced composites formed by other bio-based polymers or bio-degradable biopolymers (as matrix) and natural fiber (as reinforcement) should be explored.…”

Compression Relaxation of Multi-Structure Polymer Composites in Penetrating Liquid Medium

“…Understanding the relationship between the sorption processes occurring in composites in contact with liquids, stress [ 16 ] and ORFB deformation kinetics as well as the reason for the loss of the elastic properties of polymer composites is important for various applications [ 16 , 17 , 18 ] and for the uninterrupted operation of offset printing machines [ 18 ].…”

Research on Low-Cycle Fatigue Engineered Hybrid Sandwich Ski Construction

“…For example, sheet metal is used as an additional material. Sheets are popular because of their low cost and good mechanical properties, but their disadvantage is that they increase the weight of the resulting sandwich material [ 3 , 4 , 5 , 6 ]. Natural or synthetic material can be used as the core material.…”

“…At low cyclic fatigue, destruction of the sample should not occur within 10 thousand repetitions [ 11 , 12 , 13 ]. It is commonly reported that the strength and service life of products is reduced at low stress values during cyclic fatigue of materials, especially when polymer-based materials are used [ 3 , 6 ]. Research indicates that cyclic fatigue causes an irreversible change before the maximum strength of materials is reached [ 14 ].…”

“…When the mechanical properties of a sandwich ski structure are tested, it is preferable to use fatigue tests rather than static tests. Cyclic tests simulate the practical application in terms of long-term use [ 6 ]. The time aspect is also a very important factor that can influence the resulting properties.…”