TECHNOLOGY AREAS: Air Platform; Weapons; Materials 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 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: This topic seeks to advance the state-of-the-art in probabilistic fatigue life prediction tools for elevated-temperature, durability critical, and fracture critical metallic aerospace structural applications with limited-life design requirements. DESCRIPTION: There has been increased interest at the Air Force Research Laboratory (AFRL) and industry for an advancement in models, data, and tools to allow improved metals probabilistic performance prediction for reduced-cost, limited-life components. Components may be designed within the reduced life trade space of elevated stress, temperature, and/or environmental degradation relative to traditional material capability limits. The goal of this effort is not to develop new materials performance models for elevated temperature materials. Rather, the goal is to advance the state-of-the-art in existing probabilistic fatigue life and/or damage tolerance prediction tools to include the relevant mechanisms that drive metals behavior in limited-life conditions. These driving mechanisms are expected to be application dependent and may include, but are not limited to crack-tip plasticity, oxidation, and time-dependent behavior (creep- or dwell-fatigue.) Additionally, influences from microstructure and microstructure scale features (porosity, inclusions, surface roughness) shall be considered in the life prediction approach. Titanium alloys and Ni-base super alloys are anticipated to be the choice for low-cost, limited-life elevated temperature applications and are the preferred materials. A product form requirement is not defined but is anticipated to include wrought or various additive manufacturing modalities. An expected outcome of this effort is the verification and experimental validation of the implemented models and tools, as well as demonstration through a relevant component provided with support of an OEM partner. PHASE I: As this is a Direct-to-Phase-II (D2P2) topic, no Phase I awards will be made as a result of this topic. To qualify for this D2P2 topic, the Air Force expects the applicant(s) to demonstrate feasibility by means of a prior Phase I-type effort that does not constitute work undertaken as part of a prior or ongoing SBIR/STTR funding agreement. This includes determining, insofar as possible, the scientific and technical merit and feasibility of ideas appearing to have commercial potential. It must have validated the product-market fit between the proposed solution and a potential AF stakeholder. The applicant should have defined a clear, immediately actionable plan with the proposed solution and the AF customer. Phase I type efforts include having demonstrated feasibility via prior development of fatigue life prediction tools for durability-critical or fracture-critical metallic structural components. Critically, a customer such as an aerospace OEM or Air Force office should be identified, and evidence of collaboration and a letter of support is highly recommended. PHASE II: Under the Phase II effort, the awardee(s) shall sufficiently develop the technical approach and probabilistic life prediction software tool to conduct relevant demonstrations. Identification of predictive tool issues and/or business model modifications required to further improve the software relevance to the customer should be documented. These Phase II awards are intended to provide a path to commercialization, not the final step for the proposed solution. The successful Phase II effort will develop a probabilistic life prediction capability verified and validated for at least one alloy & product form for a particular component class as defined by an OEM collaborator, but two alloy / product forms are preferred. The limited-life application demonstration should be applied to a component design that is intended to survive for a fraction of the lifetime of an equivalent component in a conventional, long-life aerospace system. Demonstration will require more severe conditions of stress, temperature, and/or environment to survive for the reduced service life. Increases in at least two drivers (stress, temperature, dwell time, environment, ...) should be included in the demonstration. At a minimum, experimental validation should be conducted on coupon specimens, and/or with existing data, however, subscale testing is recommended. PHASE III DUAL USE APPLICATIONS: Phase III or Phase II enhancements shall include collaborative efforts with the customers to validate and support the verified workflows. Phase III shall provide businesses workflows that have been verified and validated to an acceptable degree, as deemed by the customer. Options for service contracts for continual support based on these efforts should also be provided. Expected Technology Readiness Level (TRL): 6 REFERENCES: 1. Sadeghi, E, et.al., A state-of-the-art review of fatigue performance of powder bed fusion-built alloy 718, Progress in Materials Science, vol 133, 2023. KEYWORDS: Limited-life; life prediction; probabilistic; creep-fatigue; dwell-fatigue; oxidation; verification; validation
