Manufacturing Supply Chain

Manufacturing Supply Chain: Targeted Effects of Manufacturing Defects

Researchers start by measuring defects in real wind-turbine blades that have failed in the field, such as wavy fibers shown at the top. Then material test coupons can be manufactured (middle) and tested to validate computer models, which can then be used in the design process.

Defects in wind–turbine blades are site, material, and blade specific and have been shown to have a wide range of effects depending on their location, material, type, and size. Furthermore, detecting defects in thick, multiple-material laminates has proven to be challenging using off-the-shelf inspection equipment developed for other industries.

If defects cannot be detected through inspection procedures, then they must be accounted for in the design of the blade (i.e., the blades must be “overdesigned,” which means more mass, more cost, and less efficient wind turbines). An increased understanding of the effects of blade defects along with better flaw–detection methods will enable higher confidence in manufactured products and lower design margins, leading to lighter, more reliable blades.

This project seeks to understand wind-turbine blade defects both in terms of:

• the confidence level with which they can be detected, as well as
• their ultimate effects if they are not found and remediated.

Drawing from experience inspecting composite aviation parts, Sandia has created a set of wind-blade-specific inspection specimens that mimic commonly seen blade flaws—allowing manufacturers to test and refine their equipment to better diagnose blade flaws.

Sandia will accomplish this by performing a probability of detection (POD) experiment using nondestructive inspection equipment and realistic, flawed blade specimens, along with mechanical testing and computational modeling of flawed blade coupons and substructures.

The POD experiment will consist of designing and producing a set of flawed wind–blade laminate and substructure specimens that will be blindly inspected by technicians using a variety of inspection equipment.

This project’s ultimate goal is to reduce uncertainty in as-manufactured wind–blade composites, enabling higher reliability and energy capture.

The Sandia project team has recently:

• designed and built multiple-scale mechanical test facility, enabling us to test wind blade composites at a large enough scale to examine relevant damage mechanisms;
• developed new methods for probabilistic blade design with the inclusion of defects, along with performing significant characterization and analysis of flaws in wind blade composites; and
• designed and manufactured initial NDI screening set to conduct first-ever comprehensive wind turbine NDI evaluation.

Our future project goals are to:

Multiple-scale wind-blade material test frame (top) along with model of bending test specimen (bottom).

• improve blade standards by quantifying the probability of detection for common wind blade manufacturing flaws and operational damage,
• develop next-generation blade inspection technology to increase probability of detection of wind blade flaws and damage, and
• improve blade standards by characterizing the effects of defects in wind blade laminates.