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

该主要研究仪器（MRI）奖支持宾州州立大学伊利分校贝伦德学院的落塔冲击测试仪器的收购。许多构件和结构的失效都是由于突然的灾难性断裂而造成的，通常没有任何预警。研究这些效应的学科是断裂力学。如果机械载荷达到临界水平，可能会发生灾难性的故障。为了了解可能导致断裂的条件，需要能够改变温度、组件形状和冲击速度等参数的测试设备。突发性骨折事件发生在非常短的时间内，比如几毫秒或几微秒。这就需要能够捕捉这些事件以进行详细研究的高速摄像机功能。跌落塔冲击测试仪器具有这些特点，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。包括金属、聚合物和复合材料在内的各种材料，都可以从断裂行为方面进行理解，这将有助于与必须设计抗失效部件和结构的行业合作伙伴进行更密切的合作。该仪器还将在大学水平的工程课程中提供关于断裂和冲击的指导，同时还支持以学生为中心的本科研究，塑料工程的工业劳动力发展，以及与中学女生的暑期拓展计划。该研究计划的主要目标是探索长期材料配方和新化学物质和微观结构分布的韧性/脆性断裂转变的速率依赖性。范围还包括使用这种技术来诱导定向聚合物样品的受控快速变形，以更好地理解热塑性塑料中的应变诱导结晶，建立在宾夕法尼亚州立大学伊利分校的既定研究基础上。提出了几种断裂建模分析理论，包括断裂基本工作、裂纹张开位移、裂纹尖端张开位移、虚拟裂纹闭合和j积分。所有这些都有局限性，通常是由基本材料特性造成的。与数值分析技术相结合，跌落塔冲击测试仪器提供的数据将允许对这些建模方法进行评估、改进和优化，适用于广泛的聚合物、金属和复合材料。其根本目标是在准确表征材料变形和裂纹扩展的基础上，实现可变形貌和结构材料的可靠断裂模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.