Monte Carlo simulation for tolerance analysis in prefabrication and offsite construction
Monte Carlo simulation for tolerance analysis in prefabrication and offsite construction
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DOI：
10.1016/j.autcon.2019.03.026
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发表时间：
2019-07-01
影响因子：
10.3
通讯作者：
Liang, Wanhua
中科院分区：
文献类型：
--
作者：
Rausch, Christopher;Nahangi, Mohammad;Liang, Wanhua
在装配装配过程中，生产几乎没有返工的组件是非现场施工的长期挑战。虽然传统的解决方案是在现场解决几何问题，但要付出巨大的返工成本，而制造优化技术可以缓解这些问题。公差分析就是这样一种方法，它被广泛应用于制造中，用来预测由于公差累积和尺寸变异性是否会产生问题。本文演示了预制结构组件上的蒙特卡罗公差模拟，其中可识别最大37毫米的变化，与最大30毫米的建成偏差相比。还探讨了工艺优化，其中通过选择替代制造工艺，与尺寸变异性相关的返工风险降低了65.6%。为了将蒙特卡罗方法与传统的分析方法进行比较，采用了简化的一维公差分析方法。与大约11毫米的实际偏差相比，蒙特卡罗方法产生的保守值为15.4毫米，而其他传统方法要么过于保守（最坏情况公差链的偏差为19.8毫米），要么过于野心（平方根公差链的偏差为4.6毫米）。通过蒙特卡罗模拟进行公差分析是一种主动设计工具，对于预制和非现场施工具有几个关键优势。首先，复杂的三维几何相互作用可以很容易地使用非常基本的公差配置建模。其次，关键连接点的潜在错位可以根据变异的概率分布进行识别和量化。最后，设计改进可以通过比较不同的施工工艺来实现，以减轻装配返工的风险。
Producing assemblies that experience little to no rework during assembly fit-up is a perennial challenge in offsite construction. While the traditional response has been to solve geometric issues onsite at the expense of large rework costs, manufacturing optimisation techniques can mitigate these issues upstream. Tolerance analysis is one such method that is widely used in manufacturing to predict if problems will occur from the accumulation of tolerances and dimensional variability. This article demonstrates Monte Carlo tolerance simulation on a prefabricated construction assembly, where variations up to 37 mm are identified compared to as-built deviations which range up to 30 mm. Process optimisation is also explored, where risk of rework related to dimensional variability is reduced by 65.6% through selection of alternate fabrication processes. To compare the Monte Carlo method to traditional analysis methods, a simplified 1-D tolerance analysis is used. Compared to an as-built deviation of roughly 11 mm, the Monte Carlo method produces a conservative value of 15.4 mm, while other traditional methods are either overly conservative (worst-case tolerance chain has a deviation of 19.8 mm), or overly ambitious (root sum square tolerance chain has a deviation of 4.6 mm). Tolerance analysis through Monte Carlo simulation is shown to be a proactive design tool with several key advantages for prefabricated and offsite construction. First, complex three-dimensional geometric interactions can be readily modelled using very basic tolerance configurations. Secondly, potential misalignments at key connection points can be identified and quantified in terms of a probability distribution of variation. Finally, design improvements can be achieved by comparing alternate construction processes to mitigate the risk of assembly rework.