Development of an inflight centrifuge screw pile installation and loading system-猫眼课题宝

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2016

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T. Al-Baghdadi;Michael Brown;J. Knappett

为了模拟螺旋桩在实际围应力水平下的原型安装行为，开发了一种新的安装和加载设备，该设备由两个独立控制的伺服电机驱动系统组成，可以在一次50g的操作中安装螺旋桩模型并进行轴向载荷测试。该系统是围绕最近安装在Dundee离心机上的可扩展驱动器控制系统架构（SACS）开发的，该系统基于具有模块化可扩展伺服驱动接口的美国国家仪器公司（National Instruments） compactRIO控制器。1:50比例的螺旋桩模型由直径为10毫米的低碳钢制成，焊接了直径为25毫米的法兰，代表了新一代用于海上可再生能源应用的更大的螺旋桩。为了验证新型执行器的性能和能力，将其安装在干燥致密砂中，深度可达200mm。本文详细介绍了飞机螺旋桩安装伺服电机驱动系统的设计思想和工作原理。力传感器和动态扭矩计，安装在SV2伺服控制液压千斤顶（即混合电液系统）的顶部，其容量高达3.2 kN，最大速度为130 mm/s，行程超过300 mm。该装置能够测量扭矩高达50 N.m，转速在0 - 5.2 rpm之间（Thorel et al., 2008）。最近，Patra等人（2014）在邓迪大学（UoD）开发了一种基于可扩展架构的单轴伺服执行器，以允许在未来添加进一步完全独立的伺服控制“轴”。在这项工作中，开发了单轴驱动，用于锚拔和贯入计测试，其能力高达50 kN，最大速度为3.1 mm/s，超过300 mm行程。本文将详细介绍如何添加第二个伺服电动驱动轴，以及如何将两个驱动电机转换为螺旋桩安装器和垂直负载测试仪，能够进行位移或力/扭矩控制。本文所描述的伺服执行器是设计用于安装和测试大（大扭矩）1:50比例模型螺纹桩在50g下飞行。螺旋桩的飞行安装是最困难的，因为它涉及控制多板螺旋桩的旋转同时控制垂直向下运动。根据目前陆上（位移控制）现场安装类似桩的经验，需要根据螺旋桩和土壤特性精确控制旋转和垂直速度，以尽量减少对土壤的干扰，即避免过度或不足的飞行，并控制/最小化垂直或“拥挤荷载”。因此，由于能够精确控制速度、角位置和加速度（伺服执行器规格见表1），因此决定使用Kollmorgen生产的两个独立的伺服电机（AKM53H和AKM54H）来提供旋转和垂直运动。这是通过使用一个带有伺服电机的滚珠丝杠系统（“主”）来将旋转运动转化为垂直位移的线性运动，如图1所示。旋转自由度是通过安装在顶部加载板上的第二个伺服电机（“从”）提供的，该伺服电机通过变速箱和定制的在线组合扭矩/轴向测压元件（安装在螺钉桩模型上方，为了清晰起见，未在图1中显示）旋转多板螺钉桩。在两个轴上都使用齿轮来增加伺服电机提供的扭矩。主伺服电机（主，垂直控制）采用1:6.67的传动比，而第二个电机（从，旋转控制）采用1:4的传动比来增加安装扭矩。图1所示。在容器上放置新的伺服致动器后的螺旋桩离心机试验装置示意图（注意螺旋桩由单片组成，而不是如图所示的连续螺旋）。表1。伺服执行器性能规范。_____________________________________________ 规范垂直旋转 _____________________________________________ 中风的300毫米__ Max。速度1.67 mm/s 100 rpm* Min。速度0.016 mm / s 1 rpm *容量±10 kN 30新墨西哥州 _____________________________________________ * 转:转每分钟。3仪器仪表和控制

To simulate the prototype installation behaviour of screw piles at realistic confining stress levels, a new installation and loading rig, consisting of two independently-controlled servo-motor drive systems was developed to allow screw pile models to be installed and axially load-tested inflight in one operation at 50 g. This system was developed around the Scalable Actuator Control System architecture (SACS) recently installed on the Dundee centrifuge, based around a National Instruments compactRIO controller with modularly scale-able servo drive interfaces. 1:50 scale model screw piles were manufactured from mild steel with 10 mm diameter cores with 25 mm diameter flanges welded on, representing a new generation of larger screw pile proposed for offshore marine renewable applications. These were installed up to 200 mm depth in dry dense sand to demonstrate the performance and capabilities of the new actuator. This paper details the design philosophy and operation of the servo motor actuation system for inflight screw pile installation. force sensor and dynamic torque meter, which were placed on top of an SV2 servo-controlled hydraulic jack (i.e. a hybrid electro-hydraulic system) with a capacity up to 3.2 kN and maximum speed 130 mm/s over 300 mm stroke. This device was capable of measuring torque up to 50 N.m with rotation speed between 0 5.2 rpm (Thorel et al., 2008). Recently, Patra et al. (2014) developed a single axis servo actuator at the University of Dundee (UoD) based around a scalable architecture to allow further fully independent servo-controlled ‘axes’ to be added at a future date. In this work, the single axis drive was developed for anchor pull-out and penetrometer testing, having a capacity up to 50 kN and a maximum speed 3.1 mm/s over 300 mm stroke. This paper will detail how a second servoelectric drive axis was added, along with a framework and mountings to turn the two drive motors into a screw pile installer and vertical load tester, capable of displacement or force/torque control. 2 SERVO ACTUATOR DESIGN The servo actuator described in this paper was designed to install and test large (high torque) 1:50 scale model screw piles inflight at 50-g. The installation of the screw pile inflight was considered the most difficult challenge as it involved controlled rotation of the multi-plate screw pile simultaneously with controlled vertical downward movement. Based upon experience from current onshore (displacement-controlled) field installation of similar piles, the rotational and vertical speeds need precise control based on the screw pile and soil properties to create minimum disturbance to the soil i.e. to avoid overor under-flighting and also to control/minimize the vertical or “crowding load”. Therefore, it was decided to use two independent servomotors manufactured by Kollmorgen to supply the rotational and vertical movement (AKM53H and AKM54H) due to their ability to provide precise control of velocity, angular position and acceleration (the servo actuator specifications are provided in Table 1). This was achieved by using a ball screw system with one of the servomotors (‘master’) to translate the rotary motion into a linear motion for vertical displacement as shown in Figure 1. The rotational degree of freedom was provided using the second servo motor (‘slave’) mounted on the top loading plate that rotated the multi-plate screw pile via a gearbox and a custom-built in-line combined torque/axial load cell (mounted above the screw pile model, and not shown for clarity in Figure 1). Gears were used on both axes to increase the torque supplied by the servo motors. The main servo motor (master, vertical control) utilised a gear ratio of 1:6.67, while the second motor (slave, rotational control) utilised a gear ratio of 1:4 to increase the installation torque. Figure 1. Schematic diagram of the screw pile centrifuge test setup with a new servo actuator placed on the container (note the screw pile consists of single plates rather than a continuous helical as shown). Table 1. The Servo actuator performance specifications. _____________________________________________ Specification Vertical Rotation _____________________________________________ Stroke 300 mm __ Max. Speed 1.67 mm/s 100 rpm* Min. Speed 0.016 mm/s 1 rpm* Capacity ± 10 kN 30 N.m _____________________________________________ *rpm: revolutions per minute. 3 INSTRUMENTATION AND CONTROL

Development of an inflight centrifuge screw pile installation and loading system

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