MRI: Acquisition of a Drop Tower Impact Test Capability at Penn State Erie, The Behrend College

这一重大研究仪器(MRI)奖支持宾夕法尼亚州立大学贝伦德学院购买落塔冲击测试仪器。许多部件和结构的故障是由于突然发生的灾难性骨折，这些骨折往往是在没有任何预警的情况下发生的。解决这些影响的学科是断裂力学。如果机械载荷达到临界水平，则可能发生灾难性故障。了解可能导致断裂的条件需要测试设备，这些设备可以改变温度、部件形状和撞击速度等参数。突然的骨折事件发生在非常小的时间范围内，如毫秒或微秒。这就需要高速摄像机能够捕捉到这些事件，以便进行详细研究。落塔冲击测试仪器具有这些功能，并补充了宾夕法尼亚州立大学伊利分校的一套其他测试技术。各种各样的材料，包括金属、聚合物和复合材料，都可以从断裂行为的角度进行了解，这将使我们能够与必须设计抗故障部件和结构的行业合作伙伴更紧密地合作。该仪器还将在大学水平的工程课程中教授断裂和冲击，同时还支持以学生为中心的本科生研究、塑料工程工业劳动力发展以及与中学女生的暑期外展计划。该研究计划的主要目标是探索长期存在的材料配方和新的化学成分和微观结构分布的延性/脆性断裂转变的速率依赖性。该范围还包括在宾夕法尼亚州立大学伊利已有研究的基础上，使用这项技术诱导定向聚合物样品的受控快速变形，以更好地了解热塑性塑料中的应变诱导结晶。提出了断裂基本功、裂纹张开位移、裂纹尖端张开位移、虚拟裂纹闭合和J积分等断裂建模分析理论。所有这些都有局限性，通常是由基本的材料特性强加的。结合数值分析技术，落塔冲击测试仪器能力提供的数据将使这些建模方法能够针对广泛的聚合物、金属和复合材料进行评估、发展和优化。该奖项的基本目标是基于对材料变形和裂纹扩展的准确描述，为不同形貌和结构的材料建立可靠的断裂模型。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Major Research Instrumentation (MRI) award supports the acquisition of a drop tower impact test instrument at Penn State Erie, The Behrend College. Many component and structural failures are due to sudden catastrophic fractures that often occur without warning. The discipline that addresses these effects is fracture mechanics. If mechanical loading reach critical levels, catastrophic failure may occur. Understanding the conditions that may lead to fracture requires test facilities that can vary parameters such as temperature, component shape, and impact velocity. Sudden fracture events occur over very small timeframes, like milliseconds or microseconds. This requires high speed camera capability that can capture these events for detailed study. The drop tower impact test instrument has these features and complements a set of other test techniques at Penn State Erie. A wide range of materials, including metals, polymers and composites, can be understood in terms of their fracture behavior and this will enable closer collaboration with industry partners who must design failure resistant parts and structures. This instrument will also enable instruction on fracture and impact in engineering courses at the college level, while also supporting student centered undergraduate research, industrial workforce development in plastics engineering, and a summer outreach program with middle school girls.The primary objective of the research program to be centered on this acquisition is to explore the rate-dependence of the ductile/brittle fracture transition for both longstanding material formulations and new chemistries and microstructure distributions. The scope also includes use of this technique to induce controlled rapid deformation of oriented polymer samples to better understand strain-induced crystallization in thermoplastics, building on established research at Penn State Erie. Several fracture modeling analysis theories have been planned including essential work of fracture, crack opening displacement, crack tip opening displacement, virtual crack closure, and J-integral. All of these have limitations, often imposed by the fundamental material characteristics. In combination with numerical analysis techniques, the data provided by the drop tower impact test instrument capability will allow these modeling approaches to be evaluated, evolved and optimized for a broad range of polymeric, metallic and composite materials. The fundamental goal is to achieve reliable fracture models for materials of variable morphologies and architectures based on accurate characterization of material deformation and crack propagation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.