![]() To assign the measure value to the parameter, click the Add Formula button to open the Formula Editor dialog box. Rename the created parameter from Length.1 to a meaningful name, such as SplineLength. In the New Parameter of type pull-down lists, select Length and Single Value, then click the New Parameter of type button. In the Knowledge toolbar, select the Formula icon. In the first example, I will use a formula to measure the length of the spline shown below.įirst, we create a user parameter that will hold the value of the measurement. You can look up the detailed descriptions for the functions in the CATIA’s Help system, in the Product Synthesis > Knowledge Advisor > Engineering Knowledge Language section. In this example, it says Length, which means that the function returns a value in length units. Lastly, after the colon symbol you find the type of the value that the function returns. that it could be used to measure the total length of several curves at once. The “three dots” ellipsis symbol ( …) means that the function can take any number of input parameters, i.e. In this example, it says Curve, which means the function requires a curve as the input parameter. In the parentheses, you find the function’s input parameters. The first word ( length) is the name of the function. For example, there is a distance function that lets you measure distance between any two objects, a length function for measuring length of a curve, an area function for measuring area of a surface or a closed curve, etc.Īlthough the function signatures as shown in the Members of list may initially seem cryptic, they all follow the same convention that is easy to learn. The Engineering Knowledge Language (EKL) used in CATIA’s formulas has a rich set of measurement functions, located in the Measure and the Part Measures sections of the formula editor’s Dictionary, as shown below. What is less known is that you can do the same using parameters and formulas, and this is what I will explain in this post. In particular if you are working with contact surfaces, with our without sliding, then you should use assembly mode, if not normal union mode is easier and the model is simpler.Īssembly mode means also that you will mesh each of the two boundary surfaces independentlyAny CATIA designer worth one's salt knows how to use Measure ItemĪnd Measure Between tools to make measurements. If you want to add specific physics on the boundary depends on te physics or application modes mostly you must use assembly mode to define the two boundary surfaces, each with opposed normals. The latter is mostly the default, as it means you have continuity of flux over this boundary, once you have "geomanalysed" your geometry, you have two bodies but one common boundary with "continuity". You should learn the diferences of asembled (two bodies in contact but with each it's own boundary overalapping) and union mode where both bodies have a common boundary. HOWEVER, here is the very odd result: note that the deformed shape and the z displacement output seem to be saying that the screw bends toward the negative z direction! And note the scale for the displacements - in the balpark of 1 e12 !! What is wrong? Am I missing something very basic in the model setup, leading to this absurd result? On the one hand, the ex strains look reasonable for the bending of the small screw's shaft as expected, e.g., tension on the one side and compression on the other. The puzzle is that the model appears to run fine when I am applying a distributed positively-directed z load on the top surface of the little screw I fix the boundaries of most of the bottom of the outside structure into which the small screw is placed. I did not apply any contact pairs or identity pairs where the threads meet inside. I'm doing an example stress analysis of a small screw inside of a larger structure (mainly just to make sure this problem is indeed running OK). ![]() The attached images give an idea of the example problem I'm running. I brought these new files into Comsol as stl files and assigned the properties of the two subdomains. ![]() As a followup to this thread, I wonder if you could resolve a very odd problem I'm having, which perhaps has something to do with incorrect assembly of parts (?) I should mention that I brought in these 2 parts from Mimics, where I first smoothed and remeshed the parts from original stl files.
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