1 TRUSS Chapter 17

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3 The same

4 example17.sldprt Pin support Length 1000mm Cross section 50mmx50mm E = 2e5MPa We want to find force transmitted between two trusses so we split the connecting node into two nodes.

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d d22 = f d d22 = f d d22 = f d d22 = f d31 = f31 0 = f d31 = f41 0 = f42 d21=d31 d22=d32 f21+f31=0 f22+f32= unknowns: d21 d22 d31 d32 f11 f12 f21 f22 f31 f32 f41 f42 Element 1 Element 2 Displacement continuity requirements Load components

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10 Attribution error in FEA

11 Fundamental Attribution Error Description When we are trying to understand and explain what happens in social settings, we tend to view behavior as a particularly significant factor. We then tend to explain behavior in terms of internal disposition, such as personality traits, abilities, motives, etc. as opposed to external situational factors. This can be due to our focus on the person more than their situation, about which we may know very little. We also know little about how they are interpreting the situation. Western culture exacerbates this error, as we emphasize individual freedom and autonomy and are socialized to prefer dispositional factors to situational ones. When we are playing the role of observer, which is largely when we look at others, we make this fundamental attribution error. When we are thinking about ourselves, however, we will tend to make situational attributions. Example I assume you have not done much today because you are lazy, rather than perhaps tired or lack the right resources. So what? Using it Beware of people blaming you for things outside of your control. Also watch out for people doing it to you. You can make friends and build trust when individuals are blamed by others, by showing that you understand how it is not to do with their personality. Defending Watch how others make attributions. When they seem to go against the trend and be in your favor, be curious about their motives.

12 two links solid.SLDASM Links in line

13 SOFT SPRINGS!

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How can we simplify the problem? 10000N

N d1x = 0 d1y = 0 d2x = ? d2y = ? d3x = ? d3y = ? d4x = 0 d4y = 0 f1x = ? f1y = ? f2x = ? f2y = F f3x = ? f3y = F f4x = ? f4y = ? We “split” the middle node into two nodes. This gives us 8 equations with 10 unknowns d2x = d3x d2y = d3y Then we add two equations that make displacements of node 2 and node 3 the same (remember that this is the same node) How to calculate internal force in node?

N 1 34 PROBLEM 5 25% 2 Use direct stiffness method to find nodal displacements and forces between nodes 2 and 3. Nodes 2 and 3 are coincidental. Material is steel, cross-section 50mmx20mm (see next slide). Restraints are applied to nodes 1 and 4.

18 PROBLEM 5 a2-5.SLDPRT Find forces between two elements Confirm displacement results with SW Simulation using a2-5.sldprt. Use two extrusions or two structural members. Save as problem 05.SLDPRT