The Influence of Structure of Multilayer Woven Fabrics on Their Mechanical Properties

Multilayer woven fabrics used for conveyor belts must be characterized by high mechanical strength. The design process of multilayer woven fabrics for such application requires taking into account the structural characteristics of the fabric, which allows to adjust the final product properties to the dedicated use. The geometry of warp threads—means stuffer and binding is the decisive aspect, which influences the strength properties of multilayer woven fabrics and materials made with their use as well. The aim of this work was to examine the possibility of shaping mechanical strength and bending rigidity of multilayer woven fabrics by changing the order of introducing weft threads into individual layers. The eight variants of multilayer woven fabrics were manufactured using laboratory harness loom. They were produced using different structural models in two weft variants, then tested. The mechanical features were determined, such as breaking force, recovered and unrecovered elongations in cyclic tensile test, stiffness rigidity. The analysis of the obtained results confirmed, that both the model and the order in which the weft threads were introduced into individual layers influence the mechanical strength and bending rigidity of multilayer woven. It was found, that the strength properties characterized by the above mentioned indicators are influenced by the number of threads weaved as both the stuffer and binding warp.

Silicone Implant Coated with Tranilast-Loaded Polymer in a Pattern for Fibrosis Suppression

Pathologic fibrosis around silicone implants is problematic, and thus, these implants have been coated with a mixture of a biocompatible polymer and antifibrotic drug for sustained drug release to prevent fibrosis. However, a coating applied over an entire surface would be subject to mechanical instability as the implant would be severely crumpled for implant insertion. Therefore, in this work, we proposed localized, patterned coating dots, each composed of poly(lactic-co-glycolic acid) (PLGA) and tranilast, to be applied on the surface of silicone implants. The drug loaded in the pattern-coated implant herein was well retained after a cyclic tensile test. Due to the presence of PLGA in each coating dot, the tranilast could be released in a sustained manner for more than 14 days. When implanted in a subcutaneous pocket in living rats for 12 weeks, compared with the intact implant, the pattern-coated implant showed a decreased capsule thickness and collagen density, as well as less transforming growth factor-β (TGF-β) expression and fewer fibroblasts; importantly, these changes were similar between the surfaces with and without the coating dots. Therefore, we conclude that the pattern-coating strategy proposed in this study can still effectively prevent fibrosis by maintaining the physical stability of the coatings.

Mechanical and damage tolerance behavior of short sisal fiber reinforced recycled polypropylene biocomposites

Sisal fiber (SF) reinforced recycled polypropylene biocomposites were prepared by melt blending technique. Biocomposites prepared with the incorporation of 40 wt% untreated sisal fiber loading showed a marginal improvement in mechanical properties as compared with matrix recycled polypropylene. SF surface was mercerized and maleic anhydride grafted polypropylene was used as a coupling agent for better fiber matrix interfacial bonding. Mercerized sisal fiber reinforced biocomposites prepared with compatibilizer (maleic anhydride grafted polypropylene) shows significant improvement in tensile and flexural strength. Damage tolerance of recycled polypropylene matrix and its biocomposites were evaluated in monotonic and cyclic tensile test. Untreated sisal fiber reinforced biocomposites prepared with maleic anhydride grafted polypropylene shows improvement in damage tolerance compared with untreated sisal fiber biocomposites. Impact fractured morphology of biocomposites revealed better interfacial bonding between fiber, maleic anhydride grafted polypropylene, and recycled polypropylene matrix.

Investigating on the Reverse Transformation of Martensite to Austenite and Pseudoelastic Behavior in Ultrafine-Grained Fe-10Ni-7Mn (wt %) Steel Processed by Heavy Cold Rolling

Fe-10Ni-7Mn (wt. %) steel is a member of ultrahigh strength steels which shows good ductility in the solution annealed condition and excellent age hardenability. In the current research, this alloy was subjected to heavy cold rolling in which the reverse transformation of martensitic to austenite was brought about. From the XRD, DSC and dilatometric analyses, it is resulted that after 60 % cold rolling the austenite phase may be formed by displacive mechanism. Stability of austenite at room temperature is referred to the ultrafine/nanograin size of austenite after deformation which prevents the austenite to martensite transformation. The presence of ultrafine/nanoaustenite formed by displacive mechanism leads to the observation of new mechanical properties during cyclic tensile test. This behavior is known as pseudoelastic phenomenon. In this behavior, during loading-unloading tensile cycle, the shape of the specimen return to its original configuration with a hysteresis loop in its path to the zero strain point.

Cyclic Behavior of an Industrial Brass Cu Zn32

The aim of this study is to investigate the cyclic behavior and the fatigue life of an industrial α/β brass through mechanical tests and microstructural observations. The main obtained results are about the cyclic behavior of the alloy and the characterisation of fatigue life in connection with the evolution of the microstructure. Cyclic tensile test shows a great and rapid evolution of the isotropic hardenig during cycling.