Course Length: 5 days

Pre Requisites:

Familiarity with composite manufacturing, design, or certification is required. M-1/R-1 or E-1 courses are suggested for those seeking prerequisite knowledge if necessary. At a minimum the student should be familiar with prepreg materials, layup, vacuum bagging, and curing of composites.

Summary:

The course is designed to introduce the technology to a wide range of composites personnel including material & process engineers, FAA inspectors, technicians, QA personnel, and process equipment operators.

The course has been designated to demonstrate engineering, certification and manufacturing methods for implementation of available technologies both within limits of existing specifications and to enable greater use of these technologies in future designs.

Over the five days the course will proceed from legacy platforms through model based control is intended to instruct the student in both the science and the methods for composite processing. For those wishing to attend for three days and with interests limited to manufacturing within current design specifications; these topics will be concentrated in the period Monday thru Wednesday. For those whose interests are in methods to expand the design envelope, the period Wednesday thru Friday will demonstrate features not included in current industry specifications.

Emerging technologies are focused in two areas. The first is limited to better means to measure and manage the sensors such as temperature that exist in current specifications. The second is to better model and manage material state and thereby to implement better control and process optimization within legacy specifications and to develop newer specifications that more accurately control degassing, consolidation and cure as the material changes state.

To effectively implement material state management will require collaboration between those writing specifications and those interpreting and implementing the specification. Each of these tasks become more effective if the material state is known and critical properties can then be managed. Broadly speaking the goal of this course is to educate and demonstrate that better methods are possible and can be implemented at all stages of composite processing.

The course will review the state of the art and demonstrate recent advances in technology. A discussion period will be held on the challenges of implementing material state management. Hands on training will be provided for basic tools required for implementation.

Introduction:

There has been, for many years, discussions regarding model based curing, processing science and material state management. Although there has been significant progress in equipment and software to augment existing processes, the methods for measuring and managing the materials remains essentially unchanged. This course is designed to address these issues.

The students in this course will be introduced to new methods for viscoelastic property measurement, cure model development, internal laminate and bondline temperature sensing and how these influence cost and performance factors such as material out-time, heat rate, soak time, and other variables during processing. The first two days of class will focus on ‘hands on’ training for the operation of the required software and hardware.

Days 3 and 4 will focus on the engineering considerations required to make effective use of these systems. The final half day will be used to review and discuss the barriers to and opportunities for advanced processing methods based on material science. If desired, the students who are only interested in shop activities required for material state control can limit attendance to the first two days, while those interested in the engineering aspects can limit attendance to the final 3-days of class.

Outcome, Days 1 & 2 Upon completion the students should be able to layup a part with an internal temperature sensor, link to a remote viscoelastic cure measurement unit, verify sensors place the system in a run, ready condition.

Outcome, Days 3 & 4 Upon completion students should be able to evaluate cure state data and prepare meaningful test plans to determine the effectiveness of a given cure cycle to achieve a desired viscoelastic state. The viscoelastic interpretation of both the final cure state described in CMH17 and partial cure status based on the ratio of viscous to elastic properties.

Discussion Period, Day 5 Discussions will focus on how to most effectively use the technology pending specification change and to identify critical steps to specification development based on the demonstrated technology. Because processing and process changes based on viscoelastic state processing and temperature sensing using microwires is novel, limited data exists and thus early application will first require gathering knowledge within the boundaries of existing time-temperature based specifications.

Topics:

Key Lecture Topics:

  • Emerging technologies within the legacy framework
  • Material State Management (MSM) Overview
  • Legacy cure cycles; history and limitations.
  • Computer advancements & process control software.
  • Process management using viscoelastic models.
  • Advanced microwire sensors.
  • Industry definitions and terminology for emerging systems.
  • Thermoset “cure” definition.
  • Introduction to ASTM D7750-12, Standard Test Method for Cure Behavior of Thermosetting Resins by Dynamic Mechanical Procedures using an Encapsulated Specimen Rheometer
  • CMH17 and cure (glass transition temperature (Tg) measurement methods)
  • Heat transfer & temperature distribution
  • Viscoelasticity and pressure gradients

Workshop Exercises:

  • Prepare computer based cure profiles setting target values limits and triggers
  • Conduct cure process and viscoelastic simulations
  • Software training to view and interpret cure control actions
  • Software training to compare actual viscoelastic cure from database
  • Observe prepare a composite laminate with advanced sensors in place.
  • Observe cure with real-time viscoelastic feedback from an encapsulated sample rheometer.
  • Observe and discuss the viscoelastic state of prepreg laminate during cure.
  • Produce and review QA reports and compare to existing cures.
  • Prepare a hypothetical specification based on material state.