VM-LSDYNA-WB-002

VM-LSDYNA-WB-002
Drop Analysis of a Block Onto a Spring Scale

Overview

Reference:	F. P. Beer & E. R. Johnston, Jr. (1962)Vector Mechanics for Engineers, Statics and Dynamics (5th Ed.).New York, NY: McGraw-Hill, 635.
Analysis Type(s):	Explicit Dynamics with Workbench LS-DYNA
Element Type(s):	Solid, Spring Connection
Input Files:	Link to Input Files Download Page

Test Case

A 30 kg block is dropped from a height of 2 m onto a 10 kg pan of a spring scale. The maximum deflection of the pan will be determined for a spring with a stiffness of 20 kN/m.

Figure 3: Problem Sketch

Figure 4: Workbench Model

Material Properties	Geometric Properties	Loading
Block E = 207 GPa ρ = 60 kg/m³ υ = .29 Pan E = 207 GPa ρ = 10 kg/m³ υ = .29 Spring k = 20 kN/m	Block Base = 1 m Width = 1 m Height = .5m Pan Base = 2 m Width = 2 m Height = .25 m Spring Length = 6m	The block is dropped from rest at a height of 2 m. g = 9.81 m/sec²

Material Properties

Geometric Properties

Block

E = 207 GPa

ρ = 60 kg/m³

υ = .29

Pan

E = 207 GPa

ρ = 10 kg/m³

υ = .29

Spring

k = 20 kN/m

Block

Base = 1 m

Width = 1 m

Height = .5m

Pan

Base = 2 m

Width = 2 m

Height = .25 m

Spring

Length = 6m

The block is dropped from rest at a height of 2 m.

g = 9.81 m/sec²

Analysis Assumptions and Modeling Notes

The sizes of the block, pan, and spring have been arbitrarily selected. The densities of the block and pan, however, are based on the respective volumes of each component. A relatively course mesh was chosen for both the block and pan.

Results Comparison

	Target	Workbench LS-DYNA	Error (%)
Maximum Uy of Pan	-0.25	-0.2407	–3.685