Carbon Fibre Axle (CaFiAx)

CaFiAx项目的目的是使用CFRP最大限度地减少铁路车轴的质量，以减少轨道损坏和列车二氧化碳排放。重型列车会导致高二氧化碳排放和轨道损坏。然而，趋势是朝向增加轨道车辆重量，需要更大的能量用于推进和轨道上更强烈的负载。轨道车辆的2个转向架占列车总质量（约40吨）的41%。两个轮对（1轴/2轮）安装在每个转向架框架上。重要的是，轮对（~1000 kg）与钢轨直接接触。当车轮在轨道表面滚动时，钢轨（或车轮上的扁平面）中的间隙和不规则性会引发冲击损坏，如锤击。在欧洲，每年用于维护和更新22万公里轨道基础设施的费用超过25 B欧元。在英国，英国铁路网（英语：Network Rail）（GB Railways）拥有20，000英里的轨道，并要求列车运营公司支付轨道使用费。火车越重，收费越高。Network Rail认识到轻型轮对可以节省维护费用，并为项目提供技术支持（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。很少尝试减轻轮对重量。钢轴轻量化的最佳实践是在中心钻孔。Lucchini RS是一家国际轮对制造商，报告了钻孔铁路车轴的质量为200 kg。只有通过使用密度较低的材料，才有可能进一步减轻质量。CaFiAx项目引入了一种CFRP铁路车轴，其重量至少比钢轻65%。将220型Voyager车队（34节，4节车厢配置）的车轴从钢制改为CFRP，将为列车运营商每年节省超过560万英镑的轨道通行费。CFRP管是通过将CF-环氧树脂“预浸料”织物绕圆柱形芯轴滚动制成的。每一层（对于铁路车轴为60+）是0.25至0.50 mm厚的层。该层片包括通常以0度（平行）、+/-45度或90度（垂直）取向于管的轴线的碳纤维。一旦固化，层片就不能再分离并变成复合层压材料。纤维方向控制轴刚度和动态特性。值得注意的是，CF-环氧树脂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设计优化的计算工具。-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：制作一个数据集的粘结强度性能连接金属衣领碳纤维增强塑料管。- 目标4：使用TALON与商业有限元分析软件包（Abaqus）协同生成质量优化的CFRP铁路车轴的全尺寸有限元模型。CaFiAx解决了旋转轴的基本需求：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）。在满足更高层次的需求之前，必须满足这些基本要求，例如冲击、粗暴处理、动态行为、成本、制造、替代材料等。欧盟认识到需要轻量化轮对。他们提出并资助了NEXTGEAR：WP 3-Wheelset of the Future（NEXTGEAR：881803）。预计地平线欧洲将继续提供资金。重要的是，CaFiAx项目团队为NEXTGEAR提供了所有概念和结构复合材料设计，并为英国的进一步开发做好了准备。作为NEXTGEAR的合作伙伴，Lucchini意识到了这一点，并支持CaFiAx（Lucchini LoS），劳斯莱斯也看到了航空发动机变速箱（劳斯莱斯LoS）的应用机会。

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).