Method for making a pin reinforced, crack resistant fiber reinforced composite airfoil

Abstract

A composite article, for example a blading member of a gas turbine engine, comprising a plurality of stacked layers of in-plane reinforcing fibers bonded together with a matrix resin is provided with enhanced resistance to impact cracking, material loss and / or delamination through use of a plurality of spaced apart reinforcing pins disposed into the article at an angle to the stacked layers, in one form disposed in a selected article region generally to resist strain energy generated during operation of the region. In another form, enhanced resistance is provided through the combination of a matrix resin including properties comprising a tensile strain property of at least 5% and a K1c toughness of at least about 850 psi·inch1 / 2, and a plurality of spaced apart reinforcing pins disposed into the article at an angle to the stacked layers. A method for making such a composite article with such resin comprises stacking the layers of in-plane reinforcing fibers into a shape and then inserting the reinforcing pins shape. The shape is cured with a matrix resin about the in-plane fibers of the stacked layers and about the reinforcing pins.

Description

BACKGROUND OF THE INVENTION [0001] This invention relates to a fiber reinforced composite article and method for making such article. More particularly it relates to such an article and method, for example a composite blading member including an airfoil, having generally angled or transverse pin-type reinforcing members in a toughened and enhanced resin matrix. [0002] Components for sections of gas turbine engines, for example a fan and / or a compressor, operating at relatively lower temperatures than sections downstream of the combustion section have been made of resin matrix composites including stacked, laminated layers. Generally such primarily non-metallic composite structures, which replaced heavier predominantly metal structures, include superimposed layers, sometimes called plies, reinforced with fibers substantially in the plane of the layer. As used herein, fibers include within it meaning filaments in a variety of configurations and lay-up directions, sometimes about a cor...

AI Technical Summary

Benefits of technology

[0005] The present invention, in one form, provides a composite article comprising a plurality of stacked layers of reinforcing fibers, preferably disposed in general alignment substantially unidirectionally with one another in a layer. Such aligned reinforcing fibers, sometimes called in-plane fibers, generally define at least a portion of the plane of a layer. The layers are bonded together with a matrix resin. A plurality of spaced apart reinforcing pins are disposed into the article in at least one selected region, in one embodiment across a selected region at a density that generally balances or resists a particular amount of strain energy developed during operation in the selected region. In another embodiment, the article that includes the stacked layers of such arrangement of reinforcing in-plane fibers further is toughened and provided with enhanced resistance to cracking and layer delamination. That is accomplished through use of a matrix resin that includes properties comprising a tensile strain property of greater than 5% and a K1c toughness of at least about 850 psi·inch1/2 in combination with a plurality of particular additiona

Problems solved by technology

As has been discussed in detail in such patents as the above-identified Evans et al. patent, such non-metallic composites in an aircraft gas turbine engine are subject to damage from ingestion into the engine and impact on components of foreign objects.

Impact damage to the airfoil of blading members, including fan and compressor blades, as well as damage to strut type members in the air stream, has been observed to cause loss of material and / or delamination of the stacked layers.

Such a condition in a rotating blade can cause the engine to become unbalanced resulting in potentially severe, detrimental vibration.

It has been observed, however, that disposition of such ordinary transverse reinforcement with such ordinary resin systems in modem gas turbine engine blading members such as the airfoil of a fan blade and / or without regard to what commonly is referred to in the art as strain energy developed in different portions of a blade airfoil, can result in the above-described type of damage, including delamination and / or material loss.

Such damage can reduce the operating integrity and life of a composite article.

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