Air force 16. 1 Small Business Innovation Research (sbir) Proposal Submission Instructions

5. Andrade, C., Martinez, I. & Castellote, M. Feasibility of determining corrosion rates by means of stray current-induced polarisation. Journal of applied electrochemistry 38, 1467–1476 (2008).

KEYWORDS: corrosion, aircraft structures, condition monitoring, aircraft maintenance

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop and establish alternative and effective non-destructive inspection (NDI) methods for in-service bolt and wheels currently inspected by magnetic particle (MT) and penetrant testing (PT) methods.

DESCRIPTION: All in-service Air Force aircraft wheels and steel wheel bolts are to be inspected using MT and PT NDI methods when they are rebuilt or when required by any maintenance actions. The wheels and wheel bolts of critical support equipment wheels and bolts also require periodic inspections with these NDI methods also.

MT is the most currently the most common methods used for the inspection of aircraft wheel bolts. There are thousands of wheel bolts inspected daily in Air Force NDI labs, aerospace and industry. PT is the method most commonly used for inspecting in-service aircraft and critical support equipment wheels. The major drawback for each of these methods is the generation of hazardous waste and the inspection process is associated with costly equipment, maintenance hours, and support. Another main disadvantage of MT testing is the interpretation of results due to the accumulation of particles in the thread sections. An additional problem associated with PT testing is the improper stripping and cleaning of the wheels. This causes difficulty in removing excess penetrant and generates false calls.

MT and PT have been traditionally used as the NDI methods for in-service wheels and steel bolts. The complex geometry and the improper stripping discussed above dictate that better NDI methods should be developed and established. The proposed method should eliminate the generation of hazardous waste and by extension the expensive equipment used in MT and PT inspection systems. Initial research efforts showed there could be existing alternative methods, Processed Compensation Resonance Testing (PRCT) and Sonic Infrared (SIR), for this inspection. Current inspections rely on a hit/ miss analysis. The proposed method would follow the same pattern. For the proposed effort representative examples for wheels and wheel bolts can be used; however, if necessary, discarded examples could be provide to assist in the development and preliminary evaluation of these new methods.

PHASE I: Determine potential candidate methods and perform a feasibility demonstration showing the proposed method is capable of detecting damage. If applicable, a lab-grade breadboard prototype would be sufficient.

PHASE II: Continue development of feasibility demonstration from Phase I toward creation of prototype system. Through a proof-of-concept demonstration show that the capability can be meet when taking into account system throughput.

PHASE III DUAL USE APPLICATIONS: Prepare technology for military and commercial transition including hardening of beta system from Phase II to meet depot and field requirements.

REFERENCES:

1. T.O. 33B-1-1.

2. T.O. 33B-1-2.

3. NAS 410 Certification and Qualification of NDT Personnel.

4. MIL-HDBK-6870A.

KEYWORDS: nondestructive testing inspection, non-destructive testing inspection, NDI, magnetic particle inspection, penetrant testing inspection, probability of detection

AF161-115

TITLE: Direct Measurement of Bondline Temperature During Composite Repair/Fabrication

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop improved methods to measure bond-line temperature during composite material repair or fabrication without introducing critical flaws or unduly increasing the burden/time to the repair technician.

DESCRIPTION: A better method is needed for assuring adhesives and pre-impregnated composites are fully cured during repair. Current methods for predicting if adhesives in composite materials are properly processed require the placement of multiple thermocouples around the repair site but external to the material being cured in order to avoid the introduction of a structural flaw. Even with multiple thermocouples around the repair it is difficult and sometimes impossible to assure the temperature requirements have been met at the bonding surface of the patch.

Because of the risk of failure to meet the required processing temperature, many repairs that could otherwise be managed in the field, must be returned to the depot, thereby denying access to the warfighter. Better methods are needed to measure the temperature in critical locations that are not easily verified by the current temperature measurement methods.

A solution is sought where temperature sensors could be placed at critical locations within the repair without creating a critical flaw in the repair or undue hardship on the repair technician. Further, the solution must not have any external wires or other components protruding from the repair bondline, and must be capable of providing output/feedback to monitor and control the heating of the repair in real-time. For example, one possible solution is to use temperature sensors that are small enough to be below the critical flaw size and use a magnetic field to non-destructively interrogate the sensors and provide readouts for interfacing with the hot bonder. It is theoretically possible to use such sensors to greatly improve the confidence in repairs. However, the ability to make such measurements is as yet unproven for the materials and processes required in the depot or field repair environments.

PHASE I: Develop and demonstrate proof-of-concept prototype that can measure bondline temperature of Air Force composite repairs and provide feedback to control the heating of repair. System shall be capable of measuring through glass, carbon, boron, or aramid fibers; measuring ambient temperature to 500 degrees F; wirelessly transmitting from bondline through approximately 0.150 in. of composite material.

PHASE II: Investigate accuracy and precision of the new system and determine if it exceeds current technology. Design and manufacture a working prototype that can interface with current commercial hot bonders, providing feedback for controlling the heating of the repair. Define field test objectives and conduct limited testing using composite structures similar to current aircraft composite structure/substructure. Assess the ability to field the system and its limitations. Perform a cost-benefit analysis.

PHASE III DUAL USE APPLICATIONS: Design and manufacture version ready for commercial sales. Develop and document procedures for operation, calibration and servicing.

REFERENCES:

1. Clothier, Microwire-Controlled Autoclave and Method, US Patent 8,192,080 B2, June 5 2012.

2. Clothier, Magnetic Element Temperature Sensors, US Patent 7,794,142 B2, Sept. 14 2010.

3. Clothier, Microwire Temperature Sensors Constructed to Eliminate Stress-Related Temperature Measurement Inaccuracies and Method of Manufacturing Said Sensors, US Patent Application 2012/0230365 A1, Sept. 13, 2012.

KEYWORDS: composites, bonding, bondline, temperature measurement, repair

TECHNOLOGY AREA(S): Materials/Processes

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation and within the AF Component-specific instructions. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. Please direct questions to the AF SBIR/STTR Contracting Officer, Ms. Gail Nyikon, gail.nyikon@us.af.mil.

OBJECTIVE: Develop an experimental method that can rapidly and cost-effectively characterize the local fatigue crack growth behavior in a metallic material to assess the impact of local microstructural variations.

DESCRIPTION: While metallic materials are thought to be homogeneous, they can contain significant variations in the material microstructure that results from variability in upstream processing that significantly impacts material performance. Titanium alloys, for example are prone to the development of microtexture wherein clusters of grains with similar crystallographic orientation persist over millimeter length scales.[1] These microtextured zones can significantly impact the fatigue crack growth rates – especially under loading conditions containing a tensile dwell period.[2-3] This phenomenon has contributed to a number of turbine engine incidents over the past 40 years yet a great deal of uncertainty remains. Thus, a more detailed assessment of the impact of material texture and microtexture on material performance is required.

Current research has concluded that the size, shape and intensity of the microtextured regions contribute to fatigue variability, but models to predict the growth of cracks from these regions will require better data to more accurately predict its effect.[4] Specifically, the degree and intensity of preferred orientation can significantly impact the local threshold stress intensity range for crack growth. Furthermore, the size of microtextured regions can be as large as several millimeters yet the material performance can be impacted by significantly smaller regions. Microtexture also appears to predominantly impact the plain strain crack growth behavior. The experimental technique(s) that are developed should be able to clearly measure the growth rate in individual regions as small as 0.5 mm. The technique(s) should allow for local, plain strain crack growth and/or crack growth threshold measurements that cannot be determined using conventional fracture mechanics specimens. The approach(es) should allow detailed fractography [3] of the crack path to quantify the mechanisms of crack growth. It is important that the technique(s) developed are cost effective and are not significantly more expensive than a standard crack growth test. The technique(s) should be able to include relevant loading characteristics that may include: temperature (elevated to cryogenic), atmosphere (e.g., ambient, high vacuum), and loading (constant amplitude–complex mission). The specific requirements could be best identified by a partner company.

It is envisioned that the technique(s) would be applicable to highly loaded, military and commercial aerospace structures. As such, the inclusion of an OEM partner early in the research will help to identify target applications for the technology and assist in the development of a suitable technology suite for broad applicability.

PHASE I: Develop an approach to rapidly interrogate the local crack growth behavior in a titanium alloy. Design and build a prototype to assess the feasibility of the methodology. A titanium alloy, e.g., Ti-6Al-4V, with suitable microtexture, up to 20 cubic inches, will be required and sourced either from a partner company or requested from the government TPOC.

PHASE II: Refine the experimental approach and demonstrate the capability of the approach to interrogate the local fatigue crack growth behavior under a range of loading conditions. During Phase II, identify and partner with an original equipment manufacturer that is concerned with the impact of local microstructure in the durability of their product. The contractor will need to verify and validate the cost effective technique approach over the range of loading conditions examined.

PHASE III DUAL USE APPLICATIONS: A rapid method to characterize the local crack growth behavior could find applications in several military and commercial aerospace sectors. The contractor will have to identify these markets and applications for the technology to develop a commercialization strategy.

REFERENCES:

1. N. Gey, P. Bocher, E. Uta, L. Germain, M. Humbert, “Texture and microtexture variations in a near-a titanium forged disk of bimodal microstructure,” Acta Materialia 60 (2012) 2647–2655.

2. I. Bantounas, T.C. Lindley, D. Rugg, D. Dye, “Effect of microtexture on fatigue cracking in Ti–6Al–4V,” Acta Materialia 55 (2007) 5655–5665.

3. A.L. Pilchak, “Fatigue crack growth rates in alpha titanium: Faceted vs. striation growth,” Scripta Materialia 68 (2013) 277–280.

4. A.L. Pilchak, “A simple model to account for the role of microtexture on fatigue and dwell fatigue lifetimes of titanium alloys,” Scripta Materialia 74 (2014) 68–71.

KEYWORDS: micro-texture, fatigue crack growth, local microstructure, cold dwell, titanium alloy

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop an automated capability to identify/characterize surface damage in high pressure compressor (HPC) blades and apply high speed grinding operations to reliably and repeatably perform blend repairs in an Air Force depot environment.

DESCRIPTION: The Air Force's Air Logistics Complex (ALC) at Tinker AFB, OK, is responsible for the maintenance, repair and overhaul (MRO) of all turbine engines within the Air Force fleet. Metallic HPC blades are a critical component in all jet engines and can incur erosional and impact damage during normal operation. During an engine MRO cycle these blades are routinely removed from the engine, cleaned, inspected, and either repaired or replaced based on the type of damage and the repair capability available.

A common repair technique is the use of high speed grinding to carefully blend out surface damage such as gouges, nicks, etc., primarily located on the leading and trailing edges of the blade. This is a time consuming and labor intensive process, highly reliant on individual operator skill level to accomplish acceptable removal of surface flaws. Current blend repair cycle times per blade are on the average order of 30 minutes per blemish. Typically, the ALC will identify and blend repair only several blades per month. In order to increase the depot's capability to perform blade repair in much higher part volumes, automation solutions will be necessary.

The Air Force Research Laboratory and Air Force Life Cycle Management Center are interested in developing and deploying an automated system to identify/categorize surface defects on HPC blades and then perform high speed grinding blend repairs on these blades based on defect type, size and location. HPC blade materials of interest include both nickel and titanium alloys, and sizes range from 0.5 to 24 inches. Basic blade geometry is represented by a twisted airfoil shape attached to a mating, or fir tree, structure at one end. For this topic, only the airfoil portion of the blade is to be addressed with particular attention paid to leading and trailing edges. Defects types and sizes are more fully described in Ref. 1 and associated tech orders, but are predominantly scratches, nicks and surface gouges.

Successful solutions should be able to measure defect dimensions with a repeatable dimensional accuracy that is within 3.0 percent of actuals in order to minimize ground material removal. Defect identification/characterization can be performed either manually with defect location/type data input by the operator, or automatically using CAD and scanned data and defect analysis software. However, successful proposers will recognize the AF need to efficiently collect and analyze defect data as part of an overall Digital Thread /Digital Twin strategy. Additionally, potential proposers must propose and develop a system that could be implemented into the ALC environment at Tinker AFB. Power, size, cost and integration with existing/emerging depot capabilities are all factors that should be considered in any proposed solution. Sample HPC blades can be provided as GFP to winning proposers by the Air Force upon award. The Air Force will also make available representative tech orders and depot guides to blade repair.

PHASE I: Develop and demonstrate the feasibility of critical components of the system concept described above. System designs should include defect id/characterization methodology, automation hardware and software, additional hardware, and all required external interface components. Identify user facility requirements and high-risk technologies.

PHASE II: Develop, integrate and demonstrate the critical capabilities of the proposed system defined in Phase I to validate system performance against user requirements. Demonstrations should include a set of representative Air Force parts, environment and set-up of the final solution. Develop and document prototype system to Manufacturing Readiness Level (MRL) 5-6 maturity as defined at www.dodmrl.com.

PHASE III DUAL USE APPLICATIONS: Continue prototype refinement and MRL maturity (to level 8) of the developed system to meet end user requirements for transition into the Air Force depot environments. End goal of Phase III activity is the delivery of system(s) to the end user for incorporation into their HPC blade repair facility.

REFERENCES:

1. Depot Guide to HPC Blade Blend Repair.

2. MRL Deskbook – www.dodmrl.com.

KEYWORDS: high spend grinding, automated blade repair, high pressure compressor, HPC, blade defect analysis, blade defect characterization, blend repair requirements, robotic grinding, robotic material handling, robotic material inspection

TECHNOLOGY AREA(S): Materials/Processes

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation and within the AF Component-specific instructions. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. Please direct questions to the AF SBIR/STTR Contracting Officer, Ms. Gail Nyikon, gail.nyikon@us.af.mil.

OBJECTIVE: Develop and demonstrate a repair for the blade tips/edges of integrally bladed disks (IBDs).

DESCRIPTION: Integrally bladed disks (IBDs) are highly desirable from a performance perspective and as such are now used in the fan and compressor sections of state-of-the-art military turbine engines. Unfortunately, they are also large, complex, extremely expensive, long lead items, which are subject to foreign object damage (FoD), making them difficult to maintain cost effectively. Development of a flexible and economic repair for IBD blade damage (beyond blending of minor nicks) has proven to be elusive. Efficient sustainment of engines employing IBDs requires that damaged blades can be repaired.

In a typical repair, the damaged blade tip or edge is machined away, a patch is welded on, any required post processing and heat treatment is accomplished, the patch is machined to match the original blade shape, and the repair is non-destructively inspected to ensure that the repair meets specifications. However, these state-of-the-art processes have yet to be qualified and there are numerous potential variations.

A successful proposal needs to identify a target IBD and the extent of damage that can be repaired. Alloys of interest are, Ti 6-4, Ti 6-2-4-2, Ti 6-2-4-6. In Phase I the various repair steps need to be demonstrated. Validation that the microstructure and properties of the repair are nominally equivalent to that of the parent material to within 10% is key. A Phase II award will not be made without this validation. A phase II effort, in addition to maturing and validating the repair, should evaluate the cost of repairs, seek to advance the manufacturing readiness level (MRL), and identify any remaining required qualification testing.

The proposed phase II effort should be gated (i.e. configured with sequential options). Each portion should have self-contained tasks, evaluation of TRL and MRL status, and specific milestone tests or accomplishments required for program continuation.

Teaming with a turbine engine manufacturer is highly recommended for insight into IBD performance, specifications, qualification testing, NDI requirements, cost estimates, and life management.

PHASE I: Develop and demonstrate the repair and any required post processing on coupons of the appropriate alloy with dimensions generally characteristic of the anticipated blade repair. Accomplish metallurgical characterization and mechanical testing sufficient to demonstrate that the repair has properties and microstructure that are nominally equivalent to the parent blade metal.

PHASE II: Mature the repair approach as appropriate. Accomplish mechanical characterization of repaired coupons, including HCF. Since government delivery of an actual IBD asset or sectioned blades cannot be guaranteed, demonstration of the repair, including final machining, may be conducted on, blades sectioned from an IBD, or appropriately machined and processed plate material supplied by the contractor. Accomplish repairs in a commercial facility to demonstrate MRL5.

PHASE III DUAL USE APPLICATIONS: Identify remaining qualification type testing and work with the engine OEM and government customer to accomplish it. Evaluate licensing and repair location options.

REFERENCES:

1. Navy SBIR N68335-10-C-0046.

2. MCTL DATA SHEET 1.2-6. INTEGRALLY BLADED DISK (IBD) REPAIR.

3. https://ca.dtic.mil/mctl/.

KEYWORDS: integrally bladed disk, repair, welding, probabilistic technology

AF161-119

TITLE: Non-Destructive Inspection for Repaired Integrally Bladed Disk Airfoils

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop, demonstrate, and verify a non-destructive inspection (NDI) technique to assess the integrity and microstructure state of repaired integrally bladed disk (IBD) airfoils.