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Alternative Materials for Tactical Vehicle Wheeled Hubs


OBJECTIVE: The MTVR is the current medium tactical cargo vehicle for the Marine Corps. Efforts have been made to reduce the weight of the vehicle, to accommodate extra cargo, to accommodate up-armor kits, and to improve vehicle handling. One area of development is an innovative, advanced material system to replace the currently used mild to medium strength steel in the wheel hubs of the Medium Tactical Vehicle Replacement (MTVR). Currently, the un-sprung weight of the vehicles (the combined weight of all the vehicle hardware not supported by the suspension) is on the order of 3500 lbs. By reducing this weight, the MTVR could gain improved handling characteristics, improved fuel economy and an increase in cargo capacity. DESCRIPTION: The Medium Tactical Vehicle Replacement (MTVR) Program is the current medium tactical cargo vehicle for the Marine Corps (Ref 1). Efforts are being made to identify areas that could benefit from a reduction in weight to enable extra cargo carrying capacity (e.g. up-armor kits, etc.) as well as improve vehicle handling capability. A reduction in vehicle weight directly equates to an equal increase in the vehicle load capacity. Currently used wheel hubs are made of mild to medium strength steel and the entire assembly (tire and hub) can weigh on the order of 550lbs each. The current wheel hubs are a two-piece bolt together steel disc design. They are 20 x 10 in. hubs that are sized to mount 16.00R20 XZL Michelin tires (Ref. 1). One area of potentially significant weight reduction in existing vehicles is in the wheel hubs. Reducing the weight of the wheel hubs by making them out of a lighter weight advanced material will directly benefit the handling capability of the vehicle by significantly reducing the un-sprung weight of the vehicle. The reduced wheel weight would also translate into better vehicle handling by providing improved wheel acceleration. The weight reduction would also improve the vehicle fuel efficiency (when the vehicle is not filled to maximum cargo capacity). A 35% reduction in hub weight may be able to achieve a 3% increase in fuel efficiency. The current state-of-the-art technology utilizes composite technologies which have been applied to wheels for bicycles, motorcycles and race cars. These wheels are primarily meant for relatively light vehicles used on paved surfaces for non-high-impact loads (Ref. 2-4). By contrast, a wheel hub for an MTVR will need to be capable of supporting up to 10,000 lbs. static vehicle load and operating in a more aggressive operating environment (Ref 1). This topic seeks to explore innovative, alternative, advanced material systems to replace mild to medium strength steel used in the wheel hubs for the MTVR. The use of composite material systems are encouraged, but approaches are not limited to these types of advanced material systems. Concepts that can provide a weight savings of up to 35% over the currently used steel hub assembly are of a particular interest. Proposers are encouraged to address the benefits of tailorable material solutions so that the hubs could potentially be"tuned"to work with a specific vehicle suspension. The MTVR is expected to operate in a variety of environments and terrains. The hubs need to be able to operate in the temperature range of 125 deg F to -50 deg F. Proposed concepts should be mindful of the added technical challenges to be able to maintain a"mean miles between mission"hardware failure metric of no less than 2700 miles. The hubs will also need to maintain the current Central Tire Inflation System (CTIS) capability as is discussed in Ref. 1 and will need to conform to FMVSS 119, 120, FMCSR 393.75, SAE J267, SAE J1095, SAE J1992, SAE J2014, and applicable Tire and Rim Association, or European Tire and Rim Technical Organization (ETRTO) standards. PHASE I: The company will develop e concepts for an improved wheel hub by exploring the application of advance materials while meeting the required size and strength requirements for an MTVR as discussed above. The company will demonstrate the feasibility of the concepts in meeting the Marine Corps needs and will establish that the concepts can be developed into a useful product for the Marine Corps. Feasibility will be established by material testing and analytical modeling, as appropriate, to facilitate the comparison of different concepts to include projected performance, reliability, and maintainability. The contractor shall estimate hardware, installation and maintenance costs. The company will provide a Phase II development plan with performance goals and key technical milestones, and that will address technical risks. PHASE II: Based on the results of Phase I and the Phase II development plan, the company will develop full-sized prototypes with a scaled level of performance (initial testing will evaluate on-road performance only.) The prototype hubs will be evaluated to determine their capability in meeting the reduced scale performance goals defined in the Phase II development plan and the Marine Corps requirements for the MTVR. System performance will be demonstrated through on-vehicle prototype evaluation and modeling or analytical methods as a means of validating the performance, reliability and maintainability of the prototypes. Evaluation results will be used to refine the prototype into an initial design that will meet MTVR requirements. The company will prepare a Phase III development plan to transition the technology to MTVR use. PHASE III: If Phase II is successful, the company will be expected to support the Marine Corps in transitioning the technology for Marine Corps use. The company will develop a wheeled hub for evaluation to determine its effectiveness in an operationally relevant environment. The company will support the Marine Corps for test and validation to certify and qualify the system for Marine Corps use. A successfully developed wheel hub alternative will follow a dual transition path. Some systems will be integrated onto MTVRs that are deployed in mission areas that would immediately benefit from reduced vehicle weight, while the overall system design will transition into the MTVR program as new vehicles continue to be produced. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The need to save vehicle weight exists on many industrial vehicles, including agricultural, mining, and construction equipment. Additionally, commercial freight vehicles could benefit from a system that reduces wheel assembly and vehicle weight.
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