Carbon Fibre Axle (CaFiAx)

CaFiAx项目的目标是使用碳纤维复合材料将铁路车轴的质量降至最低，以减少轨道损坏和列车二氧化碳排放。超重列车会导致高二氧化碳排放和轨道损坏。然而，趋势是增加轨道车辆的重量，需要更多的能量来推进，轨道上的负荷也更大。轨道车辆的2个转向架占列车总质量(~40吨)的41%。两个轮对(1轴/2轮)安装在每个转向架上。重要的是，轮对(约1000公斤)与钢轨直接接触。当车轮在轨道表面滚动时，轨道(或车轮上的扁平)中的间隙和不平顺会造成冲击性损坏，如锤击。在欧洲，每年花费在维护和更新22万公里轨道基础设施上的资金超过25B欧元。在英国，Network Rail(GB铁路)维护着20,000英里的轨道，并要求列车运营公司支付轨道通行费。火车越重，收费就越高。Network Rail认识到轻型轮对可以节省维护成本，并为该项目提供技术支持(Network Rail支持函(LOS))。此外，基础设施维修导致轨道关闭、乘客延误和更严重的道路拥堵。人们已经做出了一些尝试来减轻轮对的重量。钢轴轻量化的最佳做法是钻中心。国际轮对制造商Lucchini RS报告称，一根打孔的铁路线车轴的质量为200公斤。只有使用密度较低的材料，才能进一步减少质量。CaFiAx项目引入了一种碳纤维铁路车轴，其重量至少比钢轻65%。将220级旅行者车队(34节关闭，4节车厢配置)上的车轴从钢改为碳纤维，列车操作员仅在轨道进入费用上就比GB 5.6M/年节省。碳纤维管材是通过在圆柱形芯棒周围滚动碳纤维环氧预浸料制成的。每一层(铁路车轴60+)的铺层厚度在0.25到0.50毫米之间。该层由碳纤维组成，通常与管轴成0度(平行)、+/-45度或90度(垂直)。一旦固化，这些层就不能再分离，成为复合层压板。纤维方向控制着车轴的刚度和动力学性能。值得注意的是，碳纤维-环氧层压板的比疲劳强度约为钢和钛的3.5倍，而密度分别比钢和钛低75%和60%。CaFiAx项目的成功取决于4个目标的实现：-目标1：创建Talon，一种用于管状复合材料车轴和轴的优化设计的计算工具。-目标2：生成CFRP管在4点反向弯曲条件下的疲劳强度特性数据集。-目标3：编制用于连接金属环与CFRP管的粘接强度特性的数据集。-目标4：使用Talon与商业有限元分析软件包(ABAQUS)协同作用，建立质量优化的CFRP铁路轴的全尺寸有限元模型。CAFiAx解决了转轴的基本需求：通过设计满足强度要求(目标1、2和4)，并实现动力传输的元件连接(目标3)。必须先满足这些基本要求，然后才能满足更高层次的需求，如冲击、粗暴装卸、动态行为、成本、制造、替代材料等。欧盟认识到了轻量化轮对的必要性。他们提出并资助了NextGear：WP3-Wheelset of Future(NextGear：881803)。预计Horizon Europe将继续提供资金。重要的是，CaFiAx项目团队向NextGear提供了所有概念和结构复合材料设计，并为进一步在英国开发做好了准备。NextGear的合伙人Lucchini意识到了这一点，并支持CaFiAx(Lucchini Los)，劳斯莱斯也是如此，他们看到了航空发动机变速箱的应用机会(Rolls-Royce Los)。

The aim of the CaFiAx project is to minimise the mass of railway axles using CFRP to reduce track damage and train CO2 emissions.Heavy weight trains cause high CO2 emissions and track damage. The trend, however, is towards increasing rail vehicle weight, requiring greater energy for propulsion and more intense loading on the rails. The 2 bogies of a rail vehicle account for 41% of the total train mass (~40 tonnes). Two wheelsets (1 axle/2 wheels) are mounted in each bogie frame. Importantly, the wheelset (~1000 kg) is in direct contact with the rail. Gaps and irregularities in the rail (or flats on the wheel) initiate impact damage, like hammering, as the wheels roll across the track surface.In Europe, more than EUR25 B/yr is spent maintaining and renewing the 220,000 km of track infrastructure. Within the UK, Network Rail (GB Railways) maintains 20,000 miles of track and requires the Train Operating Companies to pay track access charges. The heavier the train, the higher the charge. Network Rail recognise the maintenance savings possible from a lightweight wheelset and offer their technical support to the project (Network Rail Letter of Support (LoS)). Additionally, infrastructure repairs cause track closures, passenger delays and greater road congestion.Few attempts have been made to lightweight the wheelset. Best practice for steel axle lightweighting is to bore the centre. Lucchini RS, an international wheelset manufacturer, report a mass of 200 kg for a bored railway axle. Further mass reductions are possible only by using a lower density material. The CaFiAx project introduces a CFRP railway axle that is at least 65% lighter than steel. Changing the axles on the Class 220 Voyager fleet (34 off, 4 car configuration) from steel to CFRP would save the Train Operator over £5.6 M/yr in track access charges alone.A CFRP tube is made by rolling CF-epoxy "prepreg" fabric around a cylindrical mandrel. Each layer (60+ for a railway axle) is a ply of between 0.25 to 0.50 mm thick. The ply comprises carbon fibres typically oriented at 0 deg (parallel), +/-45 or 90 deg (perpendicular) to the axis of the tube. Once cured, the plies can no longer be separated and become a composite laminate. The fibre directions control the axle stiffness and dynamic properties. Notably, a CF-epoxy laminate has ~3.5 times the specific fatigue strength of steel and titanium while being 75% and 60% less dense than steel and titanium, respectively.Success of the CaFiAx project relies on fulfilment of 4 objectives:- Objective 1: Create TALON, a computational tool for the design optimisation of tubular composite axles and shafts.- Objective 2: Produce a dataset of fatigue strength properties for CFRP tubes under 4-point reverse bending conditions. - Objective 3: Produce a dataset of bond strength properties for joining metallic collars to CFRP tubes. - Objective 4: Produce a full-scale finite element model of a mass optimised, CFRP railway axle using TALON synergistically with a commercial finite element analysis software package (Abaqus).CaFiAx addresses the fundamental needs of a rotating shaft: strength requirements are met through design (Objectives 1, 2 and 4) and elements attachment is achieved for power transmission (Objective 3). These essential requirements must be met before addressing higher order needs such as impact, rough handling, dynamic behaviour, cost, manufacture, alternate materials and others. The EU recognise the need for a lightweight wheelset. They proposed and funded, NEXTGEAR: WP3-Wheelset of the Future (NEXTGEAR: 881803). Continued Horizon Europe funding is expected. Importantly, the CaFiAx project team provided all concepts and the structural composite design to NEXTGEAR and are well placed for further, UK exploitation. Lucchini, a NEXTGEAR partner, realise this and support CaFiAx (Lucchini LoS), as do Rolls-Royce who see application opportunities for aeroengine gearboxes (Rolls-Royce LoS).