1 00:00:00,000 --> 00:00:07,000 Hi, we're students from Hugo A. Owens Middle School in Chesapeake, Virginia. 2 00:00:07,000 --> 00:00:13,000 NASA Connect asked our science and math teachers, Ms. Bernadette Smith and Ms. Angela Williams, 3 00:00:13,000 --> 00:00:17,000 to have our class investigate the strength and deflection of a composite material 4 00:00:17,000 --> 00:00:20,000 with and without the use of a reinforcement. 5 00:00:20,000 --> 00:00:25,000 Ms. Smith reviews some vocabulary terms which will help us in our composite research. 6 00:00:25,000 --> 00:00:31,000 A polymer is a large molecule built by the repetition of small, simple chemical units. 7 00:00:31,000 --> 00:00:36,000 Nylon, polyester, Teflon, and rubber are examples of polymers. 8 00:00:36,000 --> 00:00:43,000 A fiber is a long, thin strand of material such as nylon, hair, wood, or even glass. 9 00:00:43,000 --> 00:00:50,000 Stress cracks are external or internal cracks in a body caused by the application of forces to the body. 10 00:00:50,000 --> 00:00:58,000 Maximum deflection is the largest deflection that a body or structure is allowed to take while in use before failure. 11 00:00:58,000 --> 00:01:03,000 Having reviewed these terms, we are now ready to divide into our research teams. 12 00:01:03,000 --> 00:01:08,000 Here are the procedures we followed to do the experiment, and you can do it too. 13 00:01:08,000 --> 00:01:15,000 Cut out or buy six pieces of 8 by 15 centimeter poster board. 14 00:01:15,000 --> 00:01:20,000 Two of these will be used without any reinforcement or binder. 15 00:01:20,000 --> 00:01:28,000 Two will be used with the epoxy compound, and two will be used with the epoxy and a sheet of fiberglass. 16 00:01:28,000 --> 00:01:34,000 For the epoxy preparation, put on the rubber gloves and safety goggles. 17 00:01:34,000 --> 00:01:43,000 Then, squeeze out enough of the two-part epoxy to make a pool about the size of a quarter on the back of the poster board. 18 00:01:43,000 --> 00:01:47,000 Mix thoroughly with the Popsicle stick. 19 00:01:47,000 --> 00:01:52,000 Spread the epoxy evenly over the surface of the first poster board. 20 00:01:52,000 --> 00:01:57,000 Take the second poster board and press the two pieces together. 21 00:01:57,000 --> 00:02:01,000 Weigh the sample down to help consolidate it. 22 00:02:01,000 --> 00:02:07,000 After you've done this, let the epoxy-reinforced poster board dry for 10 minutes. 23 00:02:07,000 --> 00:02:12,000 Now we will prepare the fiberglass epoxy poster board composite. 24 00:02:12,000 --> 00:02:22,000 Spread the epoxy on the one side of the board with the epoxy and lay the piece of fiberglass on top of the glue. 25 00:02:22,000 --> 00:02:30,000 Once this is done, lay the back of the second poster board on top of the fiberglass and press to form a sandwich. 26 00:02:30,000 --> 00:02:36,000 The thickness of each sample is measured for strength calculation. 27 00:02:36,000 --> 00:02:41,000 Our math teacher, Mrs. Williams, provides us with the numbers. 28 00:02:41,000 --> 00:02:51,000 While the epoxy poster board and the fiberglass board are drying, it's time to begin testing the nine composite poster boards. 29 00:02:51,000 --> 00:02:55,000 Take the two flat meter sticks and have them bridge a space between the two desks. 30 00:02:55,000 --> 00:03:02,000 Using the ruler, measure the inside distance between the sticks at 6 centimeters apart so they will support the poster board. 31 00:03:02,000 --> 00:03:04,000 This is called the span. 32 00:03:04,000 --> 00:03:08,000 Once you have done this, tape down the meter sticks onto the desks. 33 00:03:08,000 --> 00:03:17,000 Tie one end of the string onto a milk jug handle and tie the other end onto a loop big enough to slide over the lengthwise part of the poster board. 34 00:03:17,000 --> 00:03:23,000 Be sure to measure out enough string so that the milk jug will dangle 5 centimeters above the ground. 35 00:03:23,000 --> 00:03:30,000 This distance from the ground is our design maximum deflection and is the design requirement of this experiment. 36 00:03:30,000 --> 00:03:35,000 Now set the poster board over the meter sticks and let the jug hang down gently. 37 00:03:35,000 --> 00:03:41,000 Carefully pour the water into the jug until the test material is dense enough to send the jug to the floor. 38 00:03:41,000 --> 00:03:44,000 Pick up the jug with the water and the string. 39 00:03:44,000 --> 00:03:49,000 Place these onto the scale to determine how much weight caused the poster board to bend or flex. 40 00:03:49,000 --> 00:03:57,000 Once we have tested the plain board, the epoxy board, and the fiberglass board, we will compare our data with the other teams. 41 00:03:58,000 --> 00:04:00,000 Now we have finished our experiment. 42 00:04:00,000 --> 00:04:09,000 Mrs. Williams helped us to think about what our data might tell us and what mathematical statements we might write to analyze the data. 43 00:04:11,000 --> 00:04:18,000 Okay, joining me in the studio are Roberta Cano, a materials research engineer at NASA Langley here in Hampton, Virginia. 44 00:04:18,000 --> 00:04:24,000 Also, Bill Millward from the Space Transportation Program at Marshall Space Flight Center in Huntsville, Alabama. 45 00:04:24,000 --> 00:04:29,000 But, before we take to our researchers and let you ask some questions, 46 00:04:29,000 --> 00:04:34,000 let's give you a chance to do your own computations using the data from the experiment you just saw. 47 00:04:34,000 --> 00:04:40,000 Then, after this segment, our two researchers will be answering your email questions and taking questions from our viewing audience. 48 00:04:40,000 --> 00:04:44,000 Okay now, look carefully at the data and using the information in the following diagram, 49 00:04:44,000 --> 00:04:49,000 work with your fellow students to answer the questions as read aloud by Dr. Catherine Fay. 50 00:04:49,000 --> 00:04:55,000 Based on the data presented, which specimen has the highest flex strength? Why? 51 00:05:19,000 --> 00:05:25,000 Based on the data presented, which specimen has the lowest flex strength? Why? 52 00:05:49,000 --> 00:05:54,000 Based on the data presented, which specimen has the highest flex strength? Why? 53 00:06:11,000 --> 00:06:16,000 Why is there such a big difference between the flex strengths of specimens 1 and 2? 54 00:06:19,000 --> 00:06:24,000 Why is there such a big difference between the flex strengths of specimens 1 and 2? 55 00:06:24,000 --> 00:06:47,260 Thanks.