TWI Ltd and Dassault Systèmes has been awarded first prize in the 2018 Additive Manufacturing Benchmark Challenge organised by the US National Institute of Standards and Technology (NIST). The companies received the award for their modelling results predicting the residual stresses within an as-built IN625 metal bridge structure.

According to the companies, the extreme thermal conditions generated during additive manufacturing (AM) processing often result in distortion leading to dimensional inaccuracy, residual stresses that impact performance and undesirable micro-structures that can affect strength. In addition, some heat treatments, based on nominal compositions and equilibrium phase diagrams, are ineffective for many AM materials and can lead to functional issues and shorter service life.

As a result, the need for a set of traceable standards and benchmark tests for the AM community was proposed by NIST and the Additive Manufacturing Benchmark test series was created.

The first round of benchmark test challenges covered laser powder bed fusion and individual bare-plate laser traces for metals. There were over 40 entries to the international competition received from North America, Europe and Asia.

Robust validation

The challenge faced by the AM community is the ability to integrate and validate computer simulations and models, especially the prediction of distortion, residual stress and micro-structure evolution, NIST says. While there have been many research developments and new software tools to address these areas, there has been a lack of publicly available, robust validation data. The aim of this new AM competition is reportedly to create a single set of benchmark tests that developers can compare, producing results that will benefit the AM community.

‘We are delighted to have won this prestigious award with Dassault Systèmes for our joint numerical modelling work on the prediction of AM distortions and residual stresses,’ said Tyler London, TWI. ‘The NIST AM-Bench series is reminiscent of the old Batelle round-robin on crack opening displacement and the more recent NeT welding residual stress round-robin, both of which have resulted in significant engineering analysis advances in their respective areas. The AM-Bench also raised quite a few questions on certain aspects of AM modelling that we look forward to investigating in the future.

This story is reprinted from material from TWI, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.