Observations on the Association between Some Buprestid and Cerambycid Beetles and Black Frankincense Resin Inducement

Samburu resin harvesters in northern Kenya maintain that frankincense resin flow from Boswellia neglecta and Commiphora confusa is induced by insect larval activity. Observations on the insects’ larval behaviour support these claims. During the frankincense harvest, buprestid beetle larvae, identified as a Sphenoptera species, are found under B. neglecta resin, eating the monoterpene-rich inner bark, which apparently stimulates the trees to produce copious amounts of fresh resin. The same behaviour was observed with cerambycid beetle larvae, identified as Neoplocaederus benningseni Kolbe, on C. confusa trees. Remarkably, these insects have developed the capacity to digest the resin-saturated inner bark and overcome the toxic, repellent characteristics of oleo-monoterpenes. The frankincense resin also appears to act as a protective covering during the insects’ larval and pupal stages. Excessive tree damage was not noted from these insect invasions. Even though the tree species are from different genera, the resin produced by both is black, with a very similar aromatic chemical profile. The question thus arises as to whether the larval feeding behaviour of these beetle species has an influence, not only on the physical appearance but also on the chemical composition of the resins.

Optimization of Injection Molding of Automotive Plastic Horn Cover Part Using Taguchi Method and Reverse Engineering

The aim of the paper consisted in the development of an injection mold for plastic horn cover parts in commercial vehicles. Three mold types were designed in anticipation of the structure and quality of molds, and injection molding numerical analyses were conducted for the three types of molds. One mold type was selected in consideration of the resin flow patterns inside the mold, surface quality, and final deflection amount of the horn cover. To perform optimal injection molding using the selected mold, optimization of injection molding parameters was performed using the Taguchi method, one of the designs of experiment (DOE) and ANOVA methods. As a result, it was confirmed that the deflection amount of the molding under optimal molding parameters decreased by about 34.3% compared to the deflection amount before optimization of the molding parameters. Based on these encouraging results, the previously selected mold type was actually manufactured. The horn cover was molded using the obtained optimal injection molding parameters to the manufactured mold. To verify the precision of the molded horn cover, the deflection amount of the molding was measured with a 3D scanner. The deflection amount of the horn cover was estimated to be about 11% to 43% larger for each measurement position than the deflection amounts in the analysis results. The manufactured mold was revised to solve the problem that the deflection amount of the actual molding is larger than the deflection amount predicted by injection molding analysis. The dimensions and surface quality of the horn cover with a revised mold were satisfactory.

RESIN FLOW SIMULATION DURING THE RTM METHOD OF COMPOSITES PRODUCTION

Processes of plastic injection molding are often under analyzes in industry and science. Many of these considerations apply to epoxy resins with additional reinforcement, often with glass or carbon fiber inside the closed mould. The simulations of injection molding processes in the production of composite elements is not as common, as thermoplasts. Hence the idea to carry out the work described in this article. The RTM (Resin Transfer Molding) method is dedicated to serial production with the possibility of producing visual carbon fiber elements for aesthetic reasons. Simulations can help to better refine the products. This allows to take appropriate precautions and solve many issues before implementation. The article presents possible situations that could occur in real conditions. Various shapes models were prepared as basis of the numerical calculations. The analyses highlighting the possible issues were performed. The influence of resin pressure and flow rate on the final product was also considered. The aim was to present the characteristic phenomena and their causes that often occur in reality to technologists working with the RTM. Conclusions related to the work carried out are included. Based on the analyzes and conclusions drawn, it is possible to improve the quality of production processes.

Effect of Varying Initial Processing Temperature on Mechanical Properties of Carbon Epoxy Composites

Use of composite materials for structural application has greatly flourished in last three decades. Mechanical properties of carbon composite are largely dependent on the processing parameters like processing temperature, compaction pressure, resin flow and fiber orientation. Processing temperature has an important and decisive role in defining the properties of the composites and absence of proper temperature can cause reduced mechanical properties and defects like wrinkles and voids. This study focuses on varying the initial processing temperature for carbon laminates and documents the effect on mechanical properties of the composite produced. The testing range of temperature was specified by the choice of resin. It was found that the mechanical properties like tensile, bending and shear strength increased non-linearly with increasing initial temperature of processing. Increase of fiber volume fraction, fiber weight fraction and density were observed which along with better resin distribution, resin flow and increased laminate compaction can be attributed as key reasons of increased mechanical properties

EVALUATION OF EFFECT OF SURFACE MODIFICATION ON CORRELATION BETWEEN PERMEABILITY OF GLASS FIBER/RESIN AND CAPILLARY NUMBER

In this study, we experimentally evaluated the correlation between the microscopic resin flow and permeability of a glass cloth, which surface was modified by silane coupling agent. We focused on the capillary number, which is a parameter determining the microscopic resin impregnation behavior within and between fiber bundles. The capillary numbers were classified into different parameters based on their dependency on temperatures and pressures. First, we obtained the temperature condition for each resin, to make the ratio between resin viscosity and (surface tension ・contact angle), constant be Under these temperature conditions, the pressure conditions were determined to be the resin impregnation rate constant. The permeability was evaluated with three types of resins under three conditions of capillary numbers. As a result, the permeabilities of the different resin systems were approximately equal. Therefore, it was found that the macroscopic permeability was not significantly influenced by the capillary number representing microscopic resin flow.

PENGARUH DEBIT ALIRAN RESIN BISPHENOL A LP-1Q-EX PADA METODE VACUUM INFUSION RESIN TERHADAP KEKUATAN TARIK KOMPOSIT SERAT KULIT POHON WARU (HIBISCUS TILIACEUS)

Research on natural fiber composites is being carried out in various parts of the world to produce solutions to environmental problems by utilizing natural fiber materials prepared for environmentally friendly and renewable materials. The natural fiber currently being developed for composite reinforcement is hibiscus bark fiber. This study aims to determine the effect of the flow rate of bisphenol A resin LP-1Q-EX on the vacuum infusion resin method on the tensile strength of hibiscus bark fiber composites. The method used in this study is the fiber structure model in the direction of tensile load, composite using hibiscus bark fiber (Hibiscus tiliaceus), composite using bisphenol A resin LP-1Q-EX, composite using mass fraction with a ratio of 60 fibers: 40 resin, Waru tree bark was treated with 6% NaOH alkaline soaking (aquades 938.8 grams, and NaOH 61.2 grams) for 120 minutes, the number of hibiscus tiliaceus bark fibers in one composite material was 22 fibers with a material thickness of 3.2 mm (according to ASTM D638-03 Type 1 standard), the composite was produced using the vacuum infusion resin method with variations in resin flow rate of 1.19 ml/s, 3.66 ml/s, 4.67 ml/s. The testing process in this study is a composite tensile test using the ASTM D638-03 Type I standard. The analysis of the fractures that occur in each specimen uses macro photos, namely the process of taking several photos of the fracture after the specimen is subjected to a tensile test using a digital camera placed on the ground. topped a tripod. The results of the composite tensile test showed that the variation of resin flow rate of 1.19 ml/s had the lowest tensile strength of 282.94 MPa, while the variation of flow discharge of 3.66 ml/s had the highest tensile strength of 301.75 MPa. and the flow variation of 4.67 ml/s has a tensile strength of 284.54 MPa. Based on the results of the tensile test of the hibiscus tiliaceus bark fiber composite using the vacuum infusion resin method, the highest strength was obtained at a variation of the resin flow rate of 3.66 ml/s.

Resin flow analysis during RTM Manufacturing of GFRP composites containing embedded impermeable inserts

The aim of this work is to analyze resin flow during RTM manufacturing of GFRP composites containing embedded impermeable inserts. High-density polyethylene inserts were embedded in the composites during processing via vacuum assisted resin transfer molding (RTM). The processing station plate was assembled so that digital image analysis of flow during and after processing could be taken. Three-point bending test specimens were cutout from the plates and their fractured surfaces were analyzed by optical fractography. Results indicate the inserts to block transverse resin flow making it difficult to wet the fibers thoroughly, which led to non-uniform plate thickness. Resin rich regions near the sides of the inserts were observed. Three-point bending failure mode analysis showed the occurrence of fiber delamination by type II shear stress, detachment between the fiber/matrix interface and the insert, and fracture of the composite to proceed by crack propagation through the resin rich region.