You’ve printed a part and it failed. Why?
您会精心完成所有应该的步骤。绘制了您的CAD型号，加载了设计域，通过您喜欢的拓扑优化工具将其运行，修复了它（使用Magics / Netfabb或其他），并用印刷制造商推荐的完美设置将其打印出来。
What happened? Well, there’s a crucial issue in most topology optimization software packages out there—they are missing an important (essential) feature. Most of them do not actually take into account how additive processes behave — which means that optimizations are taking place based on an assumption. And this assumption is invariably incorrect.
It’s the (intuitively sensible) assumption that your 3D printed part will behave the same from all directions. This is called isotropy — but, unfortunately, it is not the case.
So why even bother topologically optimizing with incorrect assumptions, and with tools that you know won’t do the job? Unless you like to invite a whole bunch of testing and insert a critical dose of ‘tacit knowledge’ into your organization — it sounds like a lot of hassle and a lot of risk.
There is a different approach. Additive Aware, from Additive Flow, is a suite of tools that optimize a subject to the nuances of additive manufacturing processes. Formflow software can help de-risk your development cycle — and harness the full potential of AM.
What is Orthotropy, and why it matters.
Orthotropy是a feature of 3D printed parts that behave differently based on the direction they are measured. Most topology optimization tools assume 3D printed parts behave the same in all directions (isotropy) – which means these results are neither accurate nor optimized.
Additive Flow’s topology optimization capability is natively built to be ‘Additive Aware’ – and optimizes shape and material subject to the varying material properties, including orthotropy. If this is not taken into account, parts can fail and opportunities will be missed.
Additive manufacturing is the meeting point of material science, design engineering, production management, and much more. It is so multi-disciplinary that the human mind — no matter how intelligent or skilled — can boggle.
This is where a new breed of tools is needed, to help our boggling minds to make the most of this exciting, if complex, technology.
As a quick material properties refresher:
Isotropy is where a material/part behaves the same way in all directions
Anisotropy is where a material/part behaves differently in one or more direction
Orthotropy是一种各向异性。Orthotropy是related to the word orthogonal, which means “connected to right angles”. So, for additive, generally, the material properties across the 90-degree directional axes of X and Y are equivalent, and Z is different (as Z is usually the build direction).
增材制造倾向于产生沿构建轴各向异性的零件。这意味着3D打印的零件是垂直于构建方向施加的力的正骨，通常较弱。
If these orthotropic properties are ignored, and engineers use the prevailing isotropic solvers on the market, results will be wrong, because they cannot take into account the actual material properties.
This means isotropic topology optimization is limited — because it is based on the false assumption that materials behave in the same way. The engineer has to choose from two bad options:
–To optimize subject to the weakest direction — hence missing optimization opportunities of additive — missing weight/cost/time-saving gains
–To optimize from an average of the material properties, which can result in key safety factors being missed — it would be certain that the weakness along the build direction was not accounted for — so how could the parts be used without further unnecessary design-test cycles?
For the majority of additive manufacturing processes that are orthotropic, how can engineers be confident about their results — and hence deploying AM in their businesses?
Composites.Orthotropy plays an even greater role with composites, where fiber alignment delivers enhanced engineering properties in specific directions. Additive manufacturing with both chopped and continuous fibers can result in seriously powerful mechanical properties. For example with an FFF process, Carbon filled ABS performed 2x to 4x better along the strongest plane in key mechanical tests vs. pure ABS.
How would the engineer properly design for these compelling material properties along certain axes? Especially when accounting for the fact that the weakness along the build direction for CFF is 50% weaker.
Orthotropic optimization.The orthotropic solvers within Additive Flow’s software stack are able to optimize topologies for single and multi-materials — accommodating both the weakness of build directions and the superpower of composites. For example, the power of the program’s solvers in the application was demonstrated in work with Royal HaskoningDHV — where they saved a further 20% in weight versus alternative isotropic solvers.
Additive Flow
www.additiveflow.com
Filed Under:Make Parts Fast
